Dairy Processing https://drinc.ucdavis.edu/dairy-processing Dairy Processing for DRINC en UC Farm Labor Management Program https://drinc.ucdavis.edu/dairy-processing/uc-farm-labor-management-program <span class="field field--name-title field--type-string field--label-hidden">UC Farm Labor Management Program</span> <span class="field field--name-uid field--type-entity-reference field--label-hidden"> <span lang="" typeof="schema:Person" property="schema:name" datatype=""> (not verified)</span> </span> <span class="field field--name-created field--type-created field--label-hidden">June 22, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-processing.rss" addthis:title="Dairy Processing" addthis:description="UC Farm Labor Management Program "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "UC Farm Labor Management Program " } } </script> <a class="addthis_button_twitter"></a> <a class="addthis_button_email"></a> <a class="addthis_button_compact"></a> </div> <div class="clearfix text-formatted field field--name-body field--type-text-with-summary field--label-hidden field__item"><p><a href="http://nature.berkeley.edu/ucce50/ag-labor/">UC Farm Labor Management Program</a></p> </div> <div class="field field--name-field-sf-article-category field--type-entity-reference field--label-above"> <div class="field__label">Category</div> <div class="field__item"><a href="/articles/dairy-processing/dairy-processing-information" hreflang="en">Dairy Processing Information</a></div> </div> Thu, 22 Jun 2017 23:40:35 +0000 Anonymous 436 at https://drinc.ucdavis.edu Manipulating Milk Protein Percentage and Production in Lactating Dairy Cows https://drinc.ucdavis.edu/dairy-processing/manipulating-milk-protein-percentage-and-production-lactating-dairy-cows <span class="field field--name-title field--type-string field--label-hidden">Manipulating Milk Protein Percentage and Production in Lactating Dairy Cows</span> <span class="field field--name-uid field--type-entity-reference field--label-hidden"> <span lang="" typeof="schema:Person" property="schema:name" datatype=""> (not verified)</span> </span> <span class="field field--name-created field--type-created field--label-hidden">June 22, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-processing.rss" addthis:title="Dairy Processing" addthis:description=""> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "" } } </script> <a class="addthis_button_twitter"></a> <a class="addthis_button_email"></a> <a class="addthis_button_compact"></a> </div> <div class="field field--name-field-sf-article-category field--type-entity-reference field--label-above"> <div class="field__label">Category</div> <div class="field__item"><a href="/articles/dairy-processing/dairy-processing-information" hreflang="en">Dairy Processing Information</a></div> </div> Thu, 22 Jun 2017 23:39:41 +0000 Anonymous 431 at https://drinc.ucdavis.edu Difficult to Manipulate Factors https://drinc.ucdavis.edu/dairy-processing/difficult-manipulate-factors <span class="field field--name-title field--type-string field--label-hidden">Difficult to Manipulate Factors</span> <span class="field field--name-uid field--type-entity-reference field--label-hidden"> <span lang="" typeof="schema:Person" property="schema:name" datatype=""> (not verified)</span> </span> <span class="field field--name-created field--type-created field--label-hidden">June 22, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-processing.rss" addthis:title="Dairy Processing" addthis:description="UCCE - COOPERATIVE EXTENSION, UNIVERSITY OF CALIFORNIA, DAVIS Manipulating Milk Protein Percentage and Production in Lactating Dairy Cows 1. Difficult to Manipulate Factors P.H. Robinson Cooperative Extension Specialist University of California, Davis, CA  95616-8521 The protein content of milk has become a much more important component of milk in recent years.  This reflects the rise in production of cheese, as well as the perception of consumers that milk fat, and fats in general, are unhealthful while milk protein is healthful.  Regardless of the reasons, dairy producers are paying more attention to the protein production of their dairy cows, both in pounds per day and as a proportion of milk, as both now influence the total value of the milk. There are a number of factors that affect the production of milk protein by dairy cows.  These reflect characteristics of the cows, the feeds that they are fed, and the environmental conditions under which they are housed.  However, few of the factors can be easily manipulated on the dairy, although considered together, they will determine both milk protein yield, and the percent in the milk, on a particular string of cows. The purpose of this article is to highlight most of the commonly accepted factors that impact milk protein production as well as milk protein percentage, but are rather difficult to manipulate on commercial dairies over the short term. Factors that Reflect the Cows A number of characteristics of the cows in the string being assessed influence the expectation of the milk protein percent and/or yield. Breed of the Cows Holsteins tend to have the lowest milk protein percentage, at between 3.15 and 3.25% protein, of all the traditional European breeds of economic importance.  In contrast, Jersey’s, at between 3.80 and 3.90% tend to be the highest.  Ayrshires (3.25 to 3.35%) and Guernseys (3.55 to 3.65%) are intermediate.  Keep in mind that since these values are full lactation averages for cows weighted over a normal distribution of lactations within a herd, individual herd values may deviate.  In addition, the absolute production of protein will not follow the same pattern.  For example, using the averages of the milk protein ranges listed above, a Holstein herd producing 25,000 lbs of milk will produce the same amount of protein as an Ayrshire herd at 24,250, a Guernsey herd at 22,200, or a Jersey herd at 20,800 lbs. Genetic Merit of Individual Cows Within all breeds, there is a range of milk protein production potential within cows that tends to cluster most of the cows around the herd average value.  However, there are generally herd average outliers, both high and low.  For example, in a group of 25 multilactation Holstein cows between weeks 6 and 12 of lactation all fed the same diet, an average milk protein percent of 2.85% was recorded with a range of between 2.55% and 3.30%.  These outliers are expressing their genetic predisposition to produce milk protein at either a high, or low, ratio to total milk.  Selection of semen from bulls with high milk test daughters is a means to increase milk protein percentage on the long term, if there is confidence in the continued value of milk protein in the future. Parity of the Cows Milk protein percentages tend to decline from first lactation to stabilize by the fourth or fifth lactation.  However these differences are relatively small after second lactation and less than the increase in protein yield that occurs over the same range of parities. Stage of Lactation of the Cows A normally fed group of Holstein cows can be expected to show a substantial difference in milk protein percentage with stage of lactation.  Typically, a milk protein percentage of about 4.0% in the first week of lactation will decline to 2.7 to 3.0% by week 5 to 6 of lactation and then show a slow increase to as high as 3.6 to 3.8% by the end of the lactation.  The sharp decline in milk protein percentage in early lactation is partly due to the residual impact of colostrum production, whereas the slow increase in later lactation reflects the relatively slower reduction in production of milk protein relative to milk lactose, which is the main determinant of milk volume.  Examining the relationship between days in milk and milk protein percentage, within parities, is an effective method to determine whether the milk protein percentages in a particular herd are relatively high, low or normal for the different stages of lactation. Factors that Reflect the Conditions of Feeding and the Rations A number of characteristics of the conditions of feeding and the rations fed to the cows in the string to be assessed influence the expectation of the milk protein percent and/or yield. Season of the Year Dairy herds in California show seasonal patterns in milk protein percentage with the lowest values during the summer and the highest values during the winter.  This difference has been shown to be in the range of 0.2 to 0.3 milk percentage units between the summer low values and winter high values.  It is not clear whether seasonal effects are simply related to high temperatures, or whether daylength is a contributing factor. Dietary Fat Level While the level of fat in the diet can be manipulated relatively easily on commercial dairies, decisions to increase or decrease fat levels in the diet are generally made relative to the energy needs of the cows, rather than the protein level of the milk.  Nevertheless, it is clear from research completed at numerous sites that dietary addition of either ruminally unprotected or protected fats is associated with reductions in the milk protein percentage by as much as 0.3 milk percentage units.  In contrast, milk protein yield is generally unchanged or slightly increased, reflecting the biology of the cow which predisposes supplemental fat to have a greater impact on production of milk fat and lactose, which is the major regulator of milk volume, than on milk protein production. The study reported from UC Davis in 1990 demonstrates that the impact may differ with the form of the added fat. Milk Yield and Composition as Influenced by Diet Fat Level   No Fish Meal   With Fish Meal     -RPFat +RPFat -RPFat +RPFat Yield (lb/d)         Milk 80.5 82.9 83.3 80.4 Fat 2.50 2.40 2.32 2.49 Protein 2.58 2.50 2.72 2.53 Milk Composition         Fat 3.10 2.90 2.90 3.10 Protein 3.21 3.02 3.27 3.15 DePeters and Palmquist (1990) RP = ruminally protected Diet Forage to Concentrate Ratio It is clear that both milk protein yield and percentage can be increased by increasing the proportion of concentrates in the ration fed to the cow.  This may be due to the associated changes in ruminal fermentation, the increased delivery of digestible nutrients at the intestinal absorptive site, or the increased flow of bacterial protein from the rumen to the intestine.  However recently reported research also indicates that very high levels of concentrate in the diet may also suppress milk protein yield and percent.  This may be the result of suppressed rumen bacterial growth associated with the acidotic rumen fermentation conditions that are typical of situations where high levels of concentrates are fed in the ration. However whatever the cause, it is not likely that commercial dairies will want to make shifts in the forage to concentrate ratio of the diet as a tool to manipulate milk protein yield or percentage.     Milk Yield and Composition as Influenced by Diet Forage to Concentate Ratio   Forage/ Concentrate Ratio (DM basis)   77/23 55/45 42/58 Yield (lb/d)       Milk 68.3 76.8 79.4 Fat 2.73 3.00 2.73 Protein 2.18 2.64 2.46 Milk Composition       Fat 4.02 3.93 3.52 Protein 3.23 3.44 3.12 Robinson and McQueen (1997) Summary An unfortunately high number of the factors that impact milk protein production cannot be easily manipulated on the dairy on the short term.  However, they are all important in allowing a rational decision to be made as to whether milk protein values, under any particular commercial situation, are high, low or normal. *      *      *      * P.H. Robinson is a Cooperative Extension Specialist responsible for dairy cattle nutrition and nutritional management.  He can be reached at: (530) 754-7565 (voice) or (530) 752-0172 (fax) or phrobinson@ucdavis.edu (EM) or animalscience.ucdavis.edu/extension/specialists.htm (web). "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "The protein content of milk has become a much more important component of milk in recent years.  This reflects the rise in production of cheese, as well as the perception of consumers that milk fat, and fats in general, are unhealthful while milk protein is healthful.  Regardless of the reasons, dairy producers are paying more attention to the protein production of their dairy cows, both in pounds per day and as a proportion of milk, as both now influence the total value of the milk. " } } </script> <a class="addthis_button_twitter"></a> <a class="addthis_button_email"></a> <a class="addthis_button_compact"></a> </div> <div class="clearfix text-formatted field field--name-body field--type-text-with-summary field--label-hidden field__item"><h2 class="heading--underline"><span><img alt="Cow Head" data-entity-type="file" data-entity-uuid="dd0849a0-fdbc-48d0-a5b2-a8ed583d32c2" src="/sites/g/files/dgvnsk1036/files/inline-images/image002.gif" class="align-right" />UCCE - COOPERATIVE EXTENSION, UNIVERSITY OF CALIFORNIA, DAVIS</span></h2> <h2><span>Manipulating Milk Protein Percentage and Production in Lactating Dairy Cows</span></h2> <h3>1. Difficult to Manipulate Factors</h3> <p><strong>P.H. Robinson</strong></p> <p><strong><span>Cooperative Extension Specialist</span></strong></p> <p><strong><span>University of California, Davis, CA<span> <span> </span></span>95616-8521</span></strong></p> <p>The protein content of milk has become a much more important component of milk in recent years.<span> <span> </span></span>This reflects the rise in production of cheese, as well as the perception of consumers that milk fat, and fats in general, are unhealthful while milk protein is healthful.<span> <span> </span></span>Regardless of the reasons, dairy producers are paying more attention to the protein production of their dairy cows, both in pounds per day and as a proportion of milk, as both now influence the total value of the milk.</p> <p>There are a number of factors that affect the production of milk protein by dairy cows.<span> <span> </span></span>These reflect characteristics of the cows, the feeds that they are fed, and the environmental conditions under which they are housed.<span> <span> </span></span>However, few of the factors can be easily manipulated on the dairy, although considered together, they will determine both milk protein yield, and the percent in the milk, on a particular string of cows.</p> <p>The purpose of this article is to highlight most of the commonly accepted factors that impact milk protein production as well as milk protein percentage, but are rather difficult to manipulate on commercial dairies over the short term.</p> <h4>Factors that Reflect the Cows</h4> <p>A number of characteristics of the cows in the string being assessed influence the expectation of the milk protein percent and/or yield.</p> <h5><em>Breed of the Cows</em></h5> <p>Holsteins tend to have the lowest milk protein percentage, at between 3.15 and 3.25% protein, of all the traditional European breeds of economic importance.<span> <span> </span></span>In contrast, Jersey’s, at between 3.80 and 3.90% tend to be the highest.<span> <span> </span></span>Ayrshires (3.25 to 3.35%) and Guernseys (3.55 to 3.65%) are intermediate.<span> <span> </span></span>Keep in mind that since these values are full lactation averages for cows weighted over a normal distribution of lactations within a herd, individual herd values may deviate.<span> <span> </span></span>In addition, the absolute production of protein will not follow the same pattern.<span> <span> </span></span>For example, using the averages of the milk protein ranges listed above, a Holstein herd producing 25,000 lbs of milk will produce the same amount of protein as an Ayrshire herd at 24,250, a Guernsey herd at 22,200, or a Jersey herd at 20,800 lbs.</p> <h5><em>Genetic Merit of Individual Cows</em></h5> <p>Within all breeds, there is a range of milk protein production potential within cows that tends to cluster most of the cows around the herd average value.<span> <span> </span></span>However, there are generally herd average outliers, both high and low.<span> <span> </span></span>For example, in a group of 25 multilactation Holstein cows between weeks 6 and 12 of lactation all fed the same diet, an average milk protein percent of 2.85% was recorded with a range of between 2.55% and 3.30%.<span> <span> </span></span>These outliers are expressing their genetic predisposition to produce milk protein at either a high, or low, ratio to total milk.<span> <span> </span></span>Selection of semen from bulls with high milk test daughters is a means to increase milk protein percentage on the long term, if there is confidence in the continued value of milk protein in the future.</p> <h5><em>Parity of the Cows</em></h5> <p>Milk protein percentages tend to decline from first lactation to stabilize by the fourth or fifth lactation.<span> <span> </span></span>However these differences are relatively small after second lactation and less than the increase in protein yield that occurs over the same range of parities.</p> <h5><em>Stage of Lactation of the Cows</em></h5> <p>A normally fed group of Holstein cows can be expected to show a substantial difference in milk protein percentage with stage of lactation.<span> <span> </span></span>Typically, a milk protein percentage of about 4.0% in the first week of lactation will decline to 2.7 to 3.0% by week 5 to 6 of lactation and then show a slow increase to as high as 3.6 to 3.8% by the end of the lactation.<span> <span> </span></span>The sharp decline in milk protein percentage in early lactation is partly due to the residual impact of colostrum production, whereas the slow increase in later lactation reflects the relatively slower reduction in production of milk protein relative to milk lactose, which is the main determinant of milk volume.<span> <span> </span></span>Examining the relationship between days in milk and milk protein percentage, within parities, is an effective method to determine whether the milk protein percentages in a particular herd are relatively high, low or normal for the different stages of lactation.</p> <h4><strong>Factors that Reflect the Conditions of Feeding and the Rations</strong></h4> <p>A number of characteristics of the conditions of feeding and the rations fed to the cows in the string to be assessed influence the expectation of the milk protein percent and/or yield.</p> <h5><em>Season of the Year</em></h5> <p>Dairy herds in California show seasonal patterns in milk protein percentage with the lowest values during the summer and the highest values during the winter.<span> <span> </span></span>This difference has been shown to be in the range of 0.2 to 0.3 milk percentage units between the summer low values and winter high values.<span> <span> </span></span>It is not clear whether seasonal effects are simply related to high temperatures, or whether daylength is a contributing factor.</p> <h5><em>Dietary Fat Level</em></h5> <p>While the level of fat in the diet can be manipulated relatively easily on commercial dairies, decisions to increase or decrease fat levels in the diet are generally made relative to the energy needs of the cows, rather than the protein level of the milk.<span> <span> </span></span>Nevertheless, it is clear from research completed at numerous sites that dietary addition of either ruminally unprotected or protected fats is associated with reductions in the milk protein percentage by as much as 0.3 milk percentage units.<span> <span> </span></span>In contrast, milk protein yield is generally unchanged or slightly increased, reflecting the biology of the cow which predisposes supplemental fat to have a greater impact on production of milk fat and lactose, which is the major regulator of milk volume, than on milk protein production.</p> <p>The study reported from UC Davis in 1990 demonstrates that the impact may differ with the form of the added fat.</p> <p>Milk Yield and Composition as Influenced by Diet Fat Level</p> <table><tbody><tr><td> </td> <td>No Fish Meal</td> <td> </td> <td>With Fish Meal</td> <td> </td> </tr><tr><td> </td> <td>-RPFat</td> <td>+RPFat</td> <td>-RPFat</td> <td>+RPFat</td> </tr><tr><td><strong>Yield (lb/d)</strong></td> <td> </td> <td> </td> <td> </td> <td> </td> </tr><tr><td>Milk</td> <td>80.5</td> <td>82.9</td> <td>83.3</td> <td>80.4</td> </tr><tr><td>Fat</td> <td>2.50</td> <td>2.40</td> <td>2.32</td> <td>2.49</td> </tr><tr><td>Protein</td> <td>2.58</td> <td>2.50</td> <td>2.72</td> <td>2.53</td> </tr><tr><td><strong>Milk Composition</strong></td> <td> </td> <td> </td> <td> </td> <td> </td> </tr><tr><td>Fat</td> <td>3.10</td> <td>2.90</td> <td>2.90</td> <td>3.10</td> </tr><tr><td>Protein</td> <td>3.21</td> <td>3.02</td> <td>3.27</td> <td>3.15</td> </tr></tbody></table><p>DePeters and Palmquist (1990)</p> <p>RP = ruminally protected</p> <h5><em>Diet Forage to Concentrate Ratio</em></h5> <p>It is clear that both milk protein yield and percentage can be increased by increasing the proportion of concentrates in the ration fed to the cow.<span> <span> </span></span>This may be due to the associated changes in ruminal fermentation, the increased delivery of digestible nutrients at the intestinal absorptive site, or the increased flow of bacterial protein from the rumen to the intestine.<span> <span> </span></span>However recently reported research also indicates that very high levels of concentrate in the diet may also suppress milk protein yield and percent.<span> <span> </span></span>This may be the result of suppressed rumen bacterial growth associated with the acidotic rumen fermentation conditions that are typical of situations where high levels of concentrates are fed in the ration.</p> <p>However whatever the cause, it is not likely that commercial dairies will want to make shifts in the forage to concentrate ratio of the diet as a tool to manipulate milk protein yield or percentage.<span>    </span></p> <p>Milk Yield and Composition as Influenced by Diet Forage to Concentate Ratio</p> <table><tbody><tr><td> </td> <td>Forage/</td> <td>Concentrate</td> <td>Ratio (DM basis)</td> </tr><tr><td> </td> <td>77/23</td> <td>55/45</td> <td>42/58</td> </tr><tr><td><strong>Yield (lb/d)</strong></td> <td> </td> <td> </td> <td> </td> </tr><tr><td>Milk</td> <td>68.3</td> <td>76.8</td> <td>79.4</td> </tr><tr><td>Fat</td> <td>2.73</td> <td>3.00</td> <td>2.73</td> </tr><tr><td>Protein</td> <td>2.18</td> <td>2.64</td> <td>2.46</td> </tr><tr><td><strong>Milk Composition</strong></td> <td> </td> <td> </td> <td> </td> </tr><tr><td>Fat</td> <td>4.02</td> <td>3.93</td> <td>3.52</td> </tr><tr><td>Protein</td> <td>3.23</td> <td>3.44</td> <td>3.12</td> </tr></tbody></table><p>Robinson and McQueen (1997)</p> <h3><strong>Summary</strong></h3> <p>An unfortunately high number of the factors that impact milk protein production cannot be easily manipulated on the dairy on the short term.<span> <span> </span></span>However, they are all important in allowing a rational decision to be made as to whether milk protein values, under any particular commercial situation, are high, low or normal.</p> <p><span>*<span>     <span> </span></span>*<span>     <span> </span></span>*<span>     <span> </span></span>*</span></p> <p><span>P.H. Robinson is a Cooperative Extension Specialist responsible for dairy cattle nutrition and nutritional management.<span> <span> </span></span>He can be reached at: (530) 754-7565 (voice) or (530) 752-0172 (fax) or<span> </span><a href="mailto:phrobinson@ucdavis.edu">phrobinson@ucdavis.edu</a><span> </span>(EM) or animalscience.ucdavis.edu/extension/specialists.htm (web).</span></p> </div> <div class="field field--name-field-sf-article-category field--type-entity-reference field--label-above"> <div class="field__label">Category</div> <div class="field__item"><a href="/articles/dairy-processing/dairy-processing-information" hreflang="en">Dairy Processing Information</a></div> </div> Thu, 22 Jun 2017 23:30:28 +0000 Anonymous 426 at https://drinc.ucdavis.edu Factors that can be Manipulated https://drinc.ucdavis.edu/dairy-processing/factors-can-be-manipulated <span class="field field--name-title field--type-string field--label-hidden">Factors that can be Manipulated</span> <span class="field field--name-uid field--type-entity-reference field--label-hidden"> <span lang="" typeof="schema:Person" property="schema:name" datatype=""> (not verified)</span> </span> <span class="field field--name-created field--type-created field--label-hidden">June 22, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-processing.rss" addthis:title="Dairy Processing" addthis:description="UCCE - COOPERATIVE EXTENSION, UNIVERSITY OF CALIFORNIA, DAVIS Manipulating Milk Protein Percentage and Production in Lactating Dairy Cows 2. Factors that can be Manipulated P.H. Robinson Cooperative Extension Specialist University of California, Davis, CA  95616-8521 The protein content of milk has become a much more important component of milk in recent years.  This reflects the rise in production of cheese, as well as the perception of consumers that milk fat, and fats in general, are unhealthful while milk protein is healthful.  Regardless of the reasons, dairy producers are paying more attention to the protein production of their dairy cows, both in pounds per day and as a proportion of milk, as both now influence the total value of the milk. There are a number of factors that affect the production of milk protein by dairy cows.  These reflect characteristics of the cows, the feeds that they are fed, and the environmental conditions under which they are housed.  Unfortunately only a few of these factors can be easily manipulated on the dairy on the short term.  However, they can be utilized effectively under commercial conditions to impact milk protein percent and/or yield. It is important to be clear on which characteristic is being discussed.  Milk protein yield (pounds of milk protein produced per cow per day) is less difficult to discuss biologically as only factors that directly impact synthesis of proteins in the udder are relevant.  Milk protein percentage is more difficult to discuss biologically as all of the factors that impact milk protein synthesis must be combined with all of the factors that impact release of water, and production other milk solids to a lesser degree, into milk.  Thus it is not uncommon to observe situations, such as advancing days in milk, where milk protein percentage rises as milk protein production declines. The purpose of this article is to highlight most of the commonly accepted factors that impact milk protein production as well as milk protein percentage, and can be manipulated on commercial dairies over the short term. Factors that can be Manipulated Prior to Calving Only one management intervention during the dry period has been demonstrated to impact milk protein percent and/or yield during the subsequent lactation. Pre-Partum Protein Feeding The level of CP in the diet of dry cows that has been recommended by the NRC has been rising since the 1971 publication (Table 1).  However experiments that have been completed since the most recent publication in 1989 suggest that even higher levels of CP Table 1.  National Research Council (NRC) recommendations for dry cows since 1971*.   1971 1978 1989** Crude protein (% DM) 8.5 11 12 NEl (Mcal/lb of DM) .50 .61 .57 TDN (% DM) 53 60 56 CP/TDN ratio  .16 .18 .21 Calcium (%DM) .34 .37 .39 Phosphorous (% DM) .26 .26 .24 Salt (% DM) .25 .25 .25 Selenium (ppm DM) .10 .10 .30 Vitamin A (IU/lb DM)  45,200 48,000 48,000 *      -  The NRC only recognizes one dry period for dairy cows. **   -  1989 is the most recent NRC dairy publication.  A revised edition is due in 1999. may be advisable, at least for the transition period of about 3 weeks immediately before calving.  Research reported from both the US and the UK has shown that higher levels of CP than those recommended by the NRC (1989), in the transition period, have been associated with numerous positive effects on cow performance including reduced  incidence of retained placenta and ketosis, higher body condition score at calving, reduced days open in the next lactation, as well as higher milk yield and higher milk protein percentage in the next lactation.  Not all of these benefits have been reported in all studies, and there is a recent study which shows no benefits at all to pre-partum protein supplementation above current recommendations.  However overall trends indicate positive benefits to higher levels of dietary CP, particularly rumen undegradable protein (RUP or UIP), in the transition period.  These ration formulation guidelines are outlined in Table 2.   Table 2.  Nutritional Guidelines for Dry Cow Rations.   Early dry mature cows Early Dry Heifers &amp; Special Needs Transition Heifers &amp; Mature Cows Energy       NEL (Mcal/lb) .50 - .55 .65 - .71 .65 - .71 Crude Protein       Total (% DM) 12 - 13 13 - 14 14 - 15 Soluble (% CP) 40 - 50 35 - 45  35 - 45 Undegraded(1) (% CP) 30 - 35 35 - 40 35 - 40 Fiber       NDF (% DM) 50 - 60 35 - 45 35 - 45 ADF (% DM) 30 - 40 25 - 35 25 - 35 1 – in the rumen Reasons for the benefits of higher levels of CP in rations fed to dry cows in the transition period are not well defined.  It is known that dairy cows have small supplies of body protein that can be mobilized in early lactation to support milk production. Nevertheless, most proposed theories revolve around a scenario in which short term feeding of high CP levels in the transition  period acts to maximize these  relatively small  protein supplies so that in early lactation they can be utilized to support milk production.  An alternate theory is that feeding higher levels of CP in the transition period allows the cow to increase maintenance protein use during this period, so that early lactation maintenance protein requirements can be reduced, for a short period, allowing more of the protein absorbed from the diet to be utilized for milk protein production in the critically important first 10 to 14 days of lactation. Factors that can be Manipulated During Lactation There are a limited number of factors that impact milk protein values and can be easily manipulated during lactation.  However, they may have other effects that should be considered before a decision is made to utilize them in practice. Post-Partum Amino Acid Supplementation Dairy cows have specific requirements for amino acids, which are the building blocks of proteins, delivered to the site of absorption in the small intestine.  There was a great deal of excitement in the 1980’s about the possibility of sharply increasing milk production of dairy cows by eliminating deficiencies of specific amino acids at the intestinal absorptive site.  In fact, there was virtually no research at the time with dairy cows that demonstrated such a possibility actually existed.  Nevertheless, a number of corporate groups invested substantial sums of money in developing the technology to coat specific amino acids to allow them to escape the rumen undegraded by ruminal bacteria and so contribute to the absorbable amino acid supply at the intestinal absorptive site.  These same groups also invested substantial sums of money in controlled research studies at University research sites and on commercial dairies.  While there seems to be little question that currently available rumen protection technology can effectively deliver targeted amino acids to the intestinal absorptive site, although it varies among commercial products, there are very few studies that have demonstrated increased milk production to doing so.  Nevertheless, a common feature of these studies was that the use of ruminally protected methionine (RPMet) did have a repeatable positive effect on milk protein yield.  In a review of nine controlled research studies, that included 13 diet comparisons, utilizing RPMet as a diet supplement, the average increase in milk protein yield was about 6%.  Remarkably, there was a positive effect in all 13 diet comparisons with increases in milk protein production ranging between 0.7% and 15.5%.  However over all studies, milk production only increased about 2%, so that the increased yield of milk protein was primarily seen as an increase in milk protein percentage. Care is required in selecting the level of RPMet to supplement in the diet as methionine is one of the few amino acids that is toxic, as has been demonstrated in monogastrics such as poultry and swine.  The RPMet dairy studies studies referred to above aimed to deliver between 3 and 10 g/d of intestinally  absorbable  methionine,  which is  equal to  between Table 3.  Impact of Oversupplying Methionine.   Study 1 – Utah(1) Study 2 – Canada(2)   Control RPMet Control RPMet Dry matter intake, lb/d 45.6 40.6 52.5 48.2 Yield, lb/d         Milk 89.9 76.5 81.3 75.5 Fat --  not reported  -- --  not reported  -- 3.04 2.98 Protein --  not reported  -- --  not reported  -- 2.62 2.47 Composition         Fat --  not reported  -- --  not reported  -- 3.75 3.92 Protein --  not reported  -- --  not reported  -- 3.22 3.26 1 – about 20 g/d of methionine delivered to the intestinal absorptive site. 2 – about 15 g/d of methionine delivered to the intestinal absorptive site. about 5 and 20% of the calculated intestinally absorbable requirement of a cow producing 90 lbs of milk per day.  These are very small amounts of material that may be very difficult to effectively mix into rations on commercial dairies.  However it is important that RPMet not be oversupplied, as there are two studies that demonstrate substantial declines of performance of dairy cows if RPMet is supplied at higher levels (Table 3).     There is certainly ample experimental data to support the use of RPMet in rations for dairy cows as a means to increase milk protein from 0.05 to 0.20 percentage units.  However, it is not recommended that RPMet be supplied at levels designed to supply more than 10 g/d of intestinally available methionine, unless there is strong reason to believe that the basal diet is suppressing delivery of intestinally absorbable methionine. Post-Partum Protein Supplementation It might seem likely that the most effective method to increase the production of milk protein would be to simply feed more protein in the diet.  However, based upon a very large body of research studies, it is clear that increasing the protein content of the diet has only a very small positive effect on milk protein production.  However, these relationships relate crude protein (CP) of the diet with milk protein yield.  If urea, as a source of dietary CP, is eliminated from the dietary CP then the positive relationship gets a bit stronger. The real difficulty in assessing the impact of protein in the diet on milk protein production is to separate diet protein which is being degraded in the rumen by rumen microbes from that which is escaping the rumen undegraded to be absorbed from the intestine.  There is no value to protein in the diet that degrades in the rumen, and is lost as ammonia, on milk protein synthesis, and there is no direct value on milk protein synthesis of protein that degrades in the rumen and is used to create microbial protein.  The value of microbial protein on milk protein synthesis is indirect, in that it must first wash out of the rumen and be absorbed from the small intestine.  In a nutshell, it is the combination of digestible microbial protein and digestible dietary escape protein that determines the quantity of absorbable protein delivered to the intestinal absorptive site, and it is the quantity of absorbable protein that may limit, or enhance, milk protein synthesis. The lack of a relationship between dietary CP intake and milk protein output is partly due to the poor relationship between dietary protein intake and the delivery of absorbable protein to the intestinal absorptive site.  A great deal of effort has been devoted to predicting delivery of intestinally absorbable protein supplies in recent years and some ration evaluation/formulation software is now available to estimate it.  However the poor relationship is also due to the ability of the animal to use protein absorbed from the intestine for production of milk proteins as well as metabolic compounds that can be used to provide energy to animal tissues. Nevertheless, there is strong circumstantial evidence that delivery of absorbable protein to the intestinal absorptive site can be one of the factors that influences milk protein yield.  Nutritional management practices that should be standard on California dairies in this regard are to supply sufficient soluble and degradable proteins in the diet to meet, but not dramatically exceed, rumen microbial requirements for protein.  In addition, sufficient supplementary dietary protein that has a high estimated proportion of protein that escapes the rumen undegraded, and has an acceptable amino acid profile, should be included in rations for all lactating cows to eliminate absorbable protein as a limitation to milk protein production.  However, there are two feeding management situations where particular attention should be paid to intestinally absorbable protein supplies. Calving Through 7 Weeks Post-Partum:  This is the period when feed intake is rising slowly to a peak, that may not occur for another 5 weeks, and milk yield has recently, or will shortly, peak.  Cows are deficient in energy during this period and will divert absorbed protein to production of intermediates that result in production of milk fat and lactose rather than to support milk protein synthesis.  Milk protein percentages that sink below 3.0% in high strings (cows "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "The protein content of milk has become a much more important component of milk in recent years. This reflects the rise in production of cheese, as well as the perception of consumers that milk fat, and fats in general, are unhealthful while milk protein is healthful. Regardless of the reasons, dairy producers are paying more attention to the protein production of their dairy cows, both in pounds per day and as a proportion of milk, as both now influence the total value of the milk. " } } </script> <a class="addthis_button_twitter"></a> <a class="addthis_button_email"></a> <a class="addthis_button_compact"></a> </div> <div class="clearfix text-formatted field field--name-body field--type-text-with-summary field--label-hidden field__item"><h2 class="heading--underline"><span><img alt="Cow Head" data-entity-type="file" data-entity-uuid="dd0849a0-fdbc-48d0-a5b2-a8ed583d32c2" src="/sites/g/files/dgvnsk1036/files/inline-images/image002.gif" class="align-right" />UCCE - COOPERATIVE EXTENSION, UNIVERSITY OF CALIFORNIA, DAVIS</span></h2> <h2><span>Manipulating Milk Protein Percentage and Production in Lactating Dairy Cows</span></h2> <h3><span>2. Factors that can be Manipulated</span></h3> <p><strong>P.H. Robinson</strong></p> <p><strong><span>Cooperative Extension Specialist</span></strong></p> <p><strong><span>University of California, Davis, CA<span> <span> </span></span>95616-8521</span></strong></p> <p>The protein content of milk has become a much more important component of milk in recent years.<span> <span> </span></span>This reflects the rise in production of cheese, as well as the perception of consumers that milk fat, and fats in general, are unhealthful while milk protein is healthful.<span> <span> </span></span>Regardless of the reasons, dairy producers are paying more attention to the protein production of their dairy cows, both in pounds per day and as a proportion of milk, as both now influence the total value of the milk.</p> <p>There are a number of factors that affect the production of milk protein by dairy cows.<span> <span> </span></span>These reflect characteristics of the cows, the feeds that they are fed, and the environmental conditions under which they are housed.<span> <span> </span></span>Unfortunately only a few of these factors can be easily manipulated on the dairy on the short term.<span> <span> </span></span>However, they can be utilized effectively under commercial conditions to impact milk protein percent and/or yield.</p> <p>It is important to be clear on which characteristic is being discussed.<span> <span> </span></span>Milk protein yield (pounds of milk protein produced per cow per day) is less difficult to discuss biologically as only factors that directly impact synthesis of proteins in the udder are relevant.<span> <span> </span></span>Milk protein percentage is more difficult to discuss biologically as all of the factors that impact milk protein synthesis must be combined with all of the factors that impact release of water, and production other milk solids to a lesser degree, into milk.<span> <span> </span></span>Thus it is not uncommon to observe situations, such as advancing days in milk, where milk protein percentage rises as milk protein production declines.</p> <p>The purpose of this article is to highlight most of the commonly accepted factors that impact milk protein production as well as milk protein percentage, and can be manipulated on commercial dairies over the short term.</p> <h4><strong>Factors that can be Manipulated Prior to Calving</strong></h4> <p>Only one management intervention during the dry period has been demonstrated to impact milk protein percent and/or yield during the subsequent lactation.</p> <p><em>Pre-Partum Protein Feeding</em></p> <p>The level of CP in the diet of dry cows that has been recommended by the NRC has been rising since the 1971 publication (Table 1).<span> <span> </span></span>However experiments that have been completed since the most recent publication in 1989 suggest that even higher levels of CP</p> <p>Table 1.<span> <span> </span></span>National Research Council (NRC) recommendations for dry cows since 1971*.</p> <div> <table><thead><tr><th> </th> <th>1971</th> <th>1978</th> <th>1989**</th> </tr></thead><tbody><tr><td>Crude protein (% DM)</td> <td>8.5</td> <td>11</td> <td>12</td> </tr><tr><td>NEl (Mcal/lb of DM)</td> <td>.50</td> <td>.61</td> <td>.57</td> </tr><tr><td>TDN (% DM)</td> <td>53</td> <td>60</td> <td>56</td> </tr><tr><td>CP/TDN ratio </td> <td>.16</td> <td>.18</td> <td>.21</td> </tr><tr><td>Calcium (%DM)</td> <td>.34</td> <td>.37</td> <td>.39</td> </tr><tr><td>Phosphorous (% DM)</td> <td>.26</td> <td>.26</td> <td>.24</td> </tr><tr><td>Salt (% DM)</td> <td>.25</td> <td>.25</td> <td>.25</td> </tr><tr><td>Selenium (ppm DM)</td> <td>.10</td> <td>.10</td> <td>.30</td> </tr><tr><td>Vitamin A (IU/lb DM) </td> <td>45,200</td> <td>48,000</td> <td>48,000</td> </tr></tbody></table></div> <p><span>*<span>     <span> </span></span>-<span> <span> </span></span>The NRC only recognizes one dry period for dairy cows.</span></p> <p><span>**<span>  <span> </span></span>-<span> <span> </span></span>1989 is the most recent NRC dairy publication.<span> <span> </span></span>A revised edition is due in 1999.</span></p> <p>may be advisable, at least for the transition period of about 3 weeks immediately before calving.<span> <span> </span></span>Research reported from both the US and the UK has shown that higher levels of CP than those recommended by the NRC (1989), in the<em><span> </span></em>transition period, have been associated with numerous positive effects on cow performance including reduced<span> <span> </span></span>incidence of retained placenta and ketosis, higher body condition score at calving, reduced days open in the next lactation, as well as higher milk yield and higher milk protein percentage in the next lactation.<span> <span> </span></span>Not all of these benefits have been reported in all studies, and there is a recent study which shows no benefits at all to pre-partum protein supplementation above current recommendations.<span> <span> </span></span>However overall trends indicate positive benefits to higher levels of dietary CP, particularly rumen undegradable protein (RUP or UIP), in the transition period.<span> <span> </span></span>These ration formulation guidelines are outlined in Table 2.</p> <p> </p> <p>Table 2.<span> <span> </span></span>Nutritional Guidelines for Dry Cow Rations.</p> <div> <table><thead><tr><th> </th> <th>Early dry mature cows</th> <th>Early Dry Heifers &amp; Special Needs</th> <th>Transition Heifers &amp; Mature Cows</th> </tr></thead><tbody><tr><td><strong>Energy</strong></td> <td> </td> <td> </td> <td> </td> </tr><tr><td>NEL (Mcal/lb)</td> <td>.50 - .55</td> <td>.65 - .71</td> <td>.65 - .71</td> </tr><tr><td><strong>Crude Protein</strong></td> <td> </td> <td> </td> <td> </td> </tr><tr><td>Total (% DM)</td> <td>12 - 13</td> <td>13 - 14</td> <td>14 - 15</td> </tr><tr><td>Soluble (% CP)</td> <td>40 - 50</td> <td>35 - 45 </td> <td>35 - 45</td> </tr><tr><td>Undegraded(1) (% CP)</td> <td>30 - 35</td> <td>35 - 40</td> <td>35 - 40</td> </tr><tr><td><strong>Fiber</strong></td> <td> </td> <td> </td> <td> </td> </tr><tr><td>NDF (% DM)</td> <td>50 - 60</td> <td>35 - 45</td> <td>35 - 45</td> </tr><tr><td>ADF (% DM)</td> <td>30 - 40</td> <td>25 - 35</td> <td>25 - 35</td> </tr></tbody></table></div> <p><em><span>1</span><span><span> </span>– in the rumen</span></em></p> <p>Reasons for the benefits of higher levels of CP in rations fed to dry cows in the transition period are not well defined.<span> <span> </span></span>It is known that dairy cows have small supplies of body protein that can be mobilized in early lactation to support milk production.<span> </span>Nevertheless, most proposed theories revolve around a scenario in which short term feeding of high CP levels in the transition<span> <span> </span></span>period acts to maximize these<span> <span> </span></span>relatively small<span> <span> </span></span>protein supplies so</p> <p>that in early lactation they can be utilized to support milk production.<span> </span></p> <p>An alternate theory is that feeding higher levels of CP in the transition period allows the cow to increase maintenance protein use during this period, so that early lactation maintenance protein requirements can be reduced, for a short period, allowing more of the protein absorbed from the diet to be utilized for milk protein production in the critically important first 10 to 14 days of lactation.</p> <h4><strong>Factors that can be Manipulated During Lactation</strong></h4> <p>There are a limited number of factors that impact milk protein values and can be easily manipulated during lactation.<span> <span> </span></span>However, they may have other effects that should be considered before a decision is made to utilize them in practice.</p> <p><em>Post-Partum Amino Acid Supplementation</em></p> <p>Dairy cows have specific requirements for amino acids, which are the building blocks of proteins, delivered to the site of absorption in the small intestine.<span> <span> </span></span>There was a great deal of excitement in the 1980’s about the possibility of sharply increasing milk production of dairy cows by eliminating deficiencies of specific amino acids at the intestinal absorptive site.<span> <span> </span></span>In fact, there was virtually no research at the time with dairy cows that demonstrated such a possibility actually existed.<span> <span> </span></span>Nevertheless, a number of corporate groups invested substantial sums of money in developing the technology to coat specific amino acids to allow them to escape the rumen undegraded by ruminal bacteria and so contribute to the absorbable amino acid supply at the intestinal absorptive site.<span> <span> </span></span>These same groups also invested substantial sums of money in controlled research studies at University research sites and on commercial dairies.<span> </span></p> <p>While there seems to be little question that currently available rumen protection technology can effectively deliver targeted amino acids to the intestinal absorptive site, although it varies among commercial products, there are very few studies that have demonstrated increased milk production to doing so.<span> <span> </span></span>Nevertheless, a common feature of these studies was that the use of ruminally protected methionine (RPMet) did have a repeatable positive effect on milk protein yield.<span> </span></p> <p>In a review of nine controlled research studies, that included 13 diet comparisons, utilizing RPMet as a diet supplement, the average increase in milk protein yield was about 6%.<span> <span> </span></span>Remarkably, there was a positive effect in all 13 diet comparisons with increases in milk protein production ranging between 0.7% and 15.5%.<span> <span> </span></span>However over all studies, milk production only increased about 2%, so that the increased yield of milk protein was primarily seen as an increase in milk protein percentage.</p> <p>Care is required in selecting the level of RPMet to supplement in the diet as methionine is one of the few amino acids that is toxic, as has been demonstrated in monogastrics such as poultry and swine.<span> <span> </span></span>The RPMet dairy studies studies referred to above aimed to deliver between 3 and 10 g/d of intestinally<span> </span><span> </span>absorbable<span> </span><span> </span>methionine,<span> </span><span> </span>which is<span> </span><span> </span>equal to<span> </span><span> </span>between</p> <p>Table 3.<span> <span> </span></span>Impact of Oversupplying Methionine.</p> <table><tbody><tr><td> </td> <td>Study 1 –</td> <td>Utah(1)</td> <td>Study 2 –</td> <td>Canada(2)</td> </tr><tr><td> </td> <td>Control</td> <td>RPMet</td> <td>Control</td> <td>RPMet</td> </tr><tr><td>Dry matter intake, lb/d</td> <td>45.6</td> <td>40.6</td> <td>52.5</td> <td>48.2</td> </tr><tr><td><strong>Yield, lb/d</strong></td> <td> </td> <td> </td> <td> </td> <td> </td> </tr><tr><td>Milk</td> <td>89.9</td> <td>76.5</td> <td>81.3</td> <td>75.5</td> </tr><tr><td>Fat</td> <td>--  not reported  --</td> <td>--  not reported  --</td> <td>3.04</td> <td>2.98</td> </tr><tr><td>Protein</td> <td>--  not reported  --</td> <td>--  not reported  --</td> <td>2.62</td> <td>2.47</td> </tr><tr><td><strong>Composition</strong></td> <td> </td> <td> </td> <td> </td> <td> </td> </tr><tr><td>Fat</td> <td>--  not reported  --</td> <td>--  not reported  --</td> <td>3.75</td> <td>3.92</td> </tr><tr><td>Protein</td> <td>--  not reported  --</td> <td>--  not reported  --</td> <td>3.22</td> <td>3.26</td> </tr></tbody></table><p><span>1</span><span><span> </span>– about 20 g/d of methionine delivered to the intestinal absorptive site.</span></p> <p><span>2</span><span><span> </span>– about 15 g/d of methionine delivered to the intestinal absorptive site.</span></p> <p>about 5 and 20% of the calculated intestinally absorbable requirement of a cow producing 90 lbs of milk per day.<span> <span> </span></span>These are very small amounts of material that may be very difficult to effectively mix into rations on commercial dairies.<span> <span> </span></span>However it is important that RPMet not be oversupplied, as there are two studies that demonstrate substantial declines of performance of dairy cows if RPMet is supplied at higher levels (Table 3).<span>    </span></p> <p>There is certainly ample experimental data to support the use of RPMet in rations for dairy cows as a means to increase milk protein from 0.05 to 0.20 percentage units.<span> <span> </span></span>However, it is not recommended that RPMet be supplied at levels designed to supply more than 10 g/d of intestinally available methionine, unless there is strong reason to believe that the basal diet is suppressing delivery of intestinally absorbable methionine.</p> <p><em>Post-Partum Protein Supplementation</em></p> <p>It might seem likely that the most effective method to increase the production of milk protein would be to simply feed more protein in the diet.<span> <span> </span></span>However, based upon a very large body of research studies, it is clear that increasing the protein content of the diet has only a very small positive effect on milk protein production.<span> <span> </span></span>However, these relationships relate crude protein (CP) of the diet with milk protein yield.<span> <span> </span></span>If urea, as a source of dietary CP, is eliminated from the dietary CP then the positive relationship gets a bit stronger.</p> <p>The real difficulty in assessing the impact of protein in the diet on milk protein production is to separate diet protein which is being degraded in the rumen by rumen microbes from that which is escaping the rumen undegraded to be absorbed from the intestine.<span> <span> </span></span>There is no value to protein in the diet that degrades in the rumen, and is lost as ammonia, on milk protein synthesis, and there is no<span> </span><strong>direct</strong><span> </span>value on milk protein synthesis of protein that degrades in the rumen and is used to create microbial protein.<span> <span> </span></span>The value of microbial protein on milk protein synthesis is indirect, in that it must first wash out of the rumen and be absorbed from the small intestine.<span> <span> </span></span>In a nutshell, it is the combination of digestible microbial protein and digestible dietary escape protein that determines the quantity of absorbable protein delivered to the intestinal absorptive site, and it is the quantity of absorbable protein that may limit, or enhance, milk protein synthesis.</p> <p>The lack of a relationship between dietary CP intake and milk protein output is partly due to the poor relationship between dietary protein intake and the delivery of absorbable protein to the intestinal absorptive site.<span> <span> </span></span>A great deal of effort has been devoted to predicting delivery of intestinally absorbable protein supplies in recent years and some ration evaluation/formulation software is now available to estimate it.<span> <span> </span></span>However the poor relationship is also due to the ability of the animal to use protein absorbed from the intestine for production of milk proteins as well as metabolic compounds that can be used to provide energy to animal tissues.</p> <p>Nevertheless, there is strong circumstantial evidence that delivery of absorbable protein to the intestinal absorptive site can be one of the factors that influences milk protein yield.<span> <span> </span></span>Nutritional management practices that should be standard on California dairies in this regard are to supply sufficient soluble and degradable proteins in the diet to meet, but not dramatically exceed, rumen microbial requirements for protein.<span> <span> </span></span>In addition, sufficient supplementary dietary protein that has a high estimated proportion of protein that escapes the rumen undegraded, and has an acceptable amino acid profile, should be included in rations for all lactating cows to eliminate absorbable protein as a limitation to milk protein production.<span> </span></p> <p>However, there are two feeding management situations where particular attention should be paid to intestinally absorbable protein supplies.</p> <p><em>Calving Through 7 Weeks Post-Partum:</em><span> <span> </span></span>This is the period when feed intake is rising slowly to a peak, that may not occur for another 5 weeks, and milk yield has recently, or will shortly, peak.<span> <span> </span></span>Cows are deficient in energy during this period and will divert absorbed protein to production of intermediates that result in production of milk fat and lactose rather than to support milk protein synthesis.<span> <span> </span></span>Milk protein percentages that sink below 3.0% in high strings (cows &lt;100 days in milk) are an indication that milk protein synthesis is being squeezed by supplies of absorbed protein.</p> <p><em>Heat Stress:</em><span> <span> </span></span>Summer heat tends to suppress feed intake more than milk yield as the metabolic drive to produce milk, particularly in high producing dairy cows, is strong.<span> <span> </span></span>Cows will continue to produce milk in quantities higher than the level of DM intake will support by mobilizing body fat reserves and by diverting absorbed protein to production of intermediates that result in production of milk fat and lactose rather than milk protein.<span> <span> </span></span>Thus, the level of slowly rumen degraded proteins in rations should go up, as DM intake is suppressed by heat, in order to reduce the extent of the depression in milk protein synthesis.</p> <h3>Summary</h3> <p>Nutrition of dairy cows is a much more sophisticated process than it has been in the past due our greater understanding of the biology of dairy cows as well as the new metabolically based ration formulation and evaluation packages that are available.<span> <span> </span></span>While there are a limited number of factors that both influence milk protein synthesis and can be modified on commercial dairies on the short term, it is important to utilize those that are available.<span> <span> </span></span>The new feed formulation software packages are a tool that your nutrition professional can use to identify conditions where action can be taken to enhance, or reduce the extent of an expected reduction, in milk protein synthesis.<span>   </span></p> <p><span>*<span>     <span> </span></span>*<span>     <span> </span></span>*<span>     <span> </span></span>*</span></p> <p><span>P.H. Robinson is a Cooperative Extension Specialist responsible for dairy cattle nutrition and nutritional management.<span> <span> </span></span>He can be reached at: (530) 754-7565 (voice) or (530) 752-0172 (fax) or<span> </span><a href="mailto:phrobinson@ucdavis.edu">phrobinson@ucdavis.edu</a><span> </span>(EM) or animalscience.ucdavis.edu/extension/specialists.htm (web).</span></p> </div> <div class="field field--name-field-sf-article-category field--type-entity-reference field--label-above"> <div class="field__label">Category</div> <div class="field__item"><a href="/articles/dairy-processing/dairy-processing-information" hreflang="en">Dairy Processing Information</a></div> </div> Thu, 22 Jun 2017 23:03:21 +0000 Anonymous 421 at https://drinc.ucdavis.edu Adulterated or Misbranded Milk or Milk Products https://drinc.ucdavis.edu/dairy-processing/adulterated-or-misbranded-milk-or-milk-products <span class="field field--name-title field--type-string field--label-hidden">Adulterated or Misbranded Milk or Milk Products</span> <span class="field field--name-uid field--type-entity-reference field--label-hidden"> <span lang="" typeof="schema:Person" property="schema:name" datatype=""> (not verified)</span> </span> <span class="field field--name-created field--type-created field--label-hidden">June 22, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-processing.rss" addthis:title="Dairy Processing" addthis:description="No person shall, produce, provide, sell, or offer for sale, or have in possession with intent to sell, offer, or expose any milk or milk product which is adulterated or misbranded. Any adulterated or misbranded milk or milk product may be impounded by the regulatory agency and disposed of in accordance with applicable laws and regulations. Adulterated food is food that:  Contains any poisonous or deleterious substance which may render it injurious to health (unless naturally occurring substances are present which are not ordinarily injurious to health). Contains a new animal drug which is unsafe. Contains a pesticide Contains an unsafe food additive. Contains any filthy, putrid, or decomposed substance. Has been prepared, packaged or held under insanitary conditions. Is the product of a diseased animal. Contains excess parts of radiation. If any substance has been substituted wholly or in part. "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "No person shall, produce, provide, sell, or offer for sale, or have in possession with intent to sell, offer, or expose any milk or milk product which is adulterated or misbranded. Any adulterated or misbranded milk or milk product may be impounded by the regulatory agency and disposed of in accordance with applicable laws and regulations. Adulterated food is food that: " } } </script> <a class="addthis_button_twitter"></a> <a class="addthis_button_email"></a> <a class="addthis_button_compact"></a> </div> <div class="clearfix text-formatted field field--name-body field--type-text-with-summary field--label-hidden field__item"><p>No person shall, produce, provide, sell, or offer for sale, or have in possession with intent to sell, offer, or expose any milk or milk product which is adulterated or misbranded. Any adulterated or misbranded milk or milk product may be impounded by the regulatory agency and disposed of in accordance with applicable laws and regulations.</p> <p>Adulterated food is food that:<span> </span></p> <div> <ul><li>Contains any poisonous or deleterious substance which may render it injurious to health (unless naturally occurring substances are present which are not ordinarily injurious to health).</li> <li>Contains a new animal drug which is unsafe.</li> <li>Contains a pesticide</li> <li>Contains an unsafe food additive.</li> <li>Contains any filthy, putrid, or decomposed substance.</li> <li>Has been prepared, packaged or held under insanitary conditions.</li> <li>Is the product of a diseased animal.</li> <li>Contains excess parts of radiation.</li> <li>If any substance has been substituted wholly or in part.</li> </ul></div> </div> <div class="field field--name-field-sf-article-category field--type-entity-reference field--label-above"> <div class="field__label">Category</div> <div class="field__item"><a href="/articles/dairy-processing/dairy-processing-information" hreflang="en">Dairy Processing Information</a></div> </div> Thu, 22 Jun 2017 23:02:26 +0000 Anonymous 416 at https://drinc.ucdavis.edu Some HTST Definitions https://drinc.ucdavis.edu/dairy-processing/some-htst-definitions <span class="field field--name-title field--type-string field--label-hidden">Some HTST Definitions</span> <span class="field field--name-uid field--type-entity-reference field--label-hidden"> <span lang="" typeof="schema:Person" property="schema:name" datatype=""> (not verified)</span> </span> <span class="field field--name-created field--type-created field--label-hidden">June 22, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-processing.rss" addthis:title="Dairy Processing" addthis:description="ATMOSPHERIC PRESSURE-- The force exerted on an area by the column of air above that area. Atmospheric pressure at sea level is 14.7 pounds per square inch. BALANCE TANK-- Raw product tank located at the start of a pasteurization system used to maintain a constant supply of product to the pasteurizer. BOOSTER PUMP-- A centrifugal pump placed in a pasteurizing system between the balance tank and the raw regenerator and capable of producing positive pressure in the raw regenerator. BOURDON COIL (spring)-- A sealed flat metal tube filled with a gas mixture that has been formed into a coiled spiral, located inside the recorder-controller. This spiral expands or contracts in response to the vapor pressure of the gas mixture. This coil is located on one end of the capillary tube with the recorder-controller temperature sensing bulb at the other. CAPILLARY TUBE-- A thin metal tube, containing a mixture of liquids with low vapor pressures, that connects the bourdon tube in the recorder-controller with the temperature sensor bulb located at the flow diversion device. This thin tube is usually protected by a flexible metal cable. CENTRIFUGAL PUMP-- A high speed pump that produces product flow due to the velocity increase of the liquid caused by the rotation of the pump impeller. CONSTANT LEVEL TANK-- See Balance Tank. COOLING SECTION-- The section of a heat exchanger (press) in which one of several non-toxic coolants flows in a counter current direction on the opposite side of a stainless steel plate of the pasteurized product. DEFLECTOR PLATE-- A stainless steel plate in the regenerator section of the press designed to change the direction of flow. FLOW DIVERSION DEVICE-- Either a single stem (one three-way valve) or dual stem device (two, three-way valves connected by a common yoke), designed to change the direction of product flow when working in conjunction with the recorder-controller. (FDD) FLOW CONTROLLER-- An instrument used in meter based systems which compares the flow signal from the flow transmitter to a set point and either controls the centrifugal pump speed or regulates a flow control valve downstream of the meter and centrifugal pump. FLOW TRANSMITTER-- An instrument used in meter based systems which converts signals from the magnetic flow meter to a 4- 20ma current. FREQUENCY PEN-- A solenoid actuated recording pen (located on the outer edge of the recording chart) that records the position of the flow diversion device in a continuous flow pasteurization system. This pen on a meter based system only records the flow diversion device position that has been electronically signaled by the flow recorder/controller. HEAT EXCHANGER-- Equipment designed to effect heat transfer between two or more mediums.(plate type, triple tubes, etc.). HOLDING TUBE-- The section of piping in continuous flow pasteurizers of sufficient length to provide the minimum legal residence time for heated milk. HOT WATER TEMPERATURE CONTROLLER-- A system which controls the temperature of the heating medium by regulating a mixture of steam and water that circulates through the heating section of the press. I/P TRANSDUCER-- An instrument used in a meter based system that converts a 4-20ma current signal to an air signal (usually 15-30 psi) which drives the flow recorder pen LAMINAR FLOW-- The movement of high viscosity products through a pipe in concentric layers where the fastest particle may move at twice the speed of the average particle METERING PUMP-- See Timing Pump PNEUMATIC-- Operated by compressed air. REGENERATOR BY-PASS VALVE-- A automatic or manually controlled valve used in combination with the booster pump for the purposes of start up of a continuous pasteurizer with a milk to milk regenerator. This valve allows for by-passing the regenerator in order to provide the proper pressure relationships in the regenerator, thus allowing the booster pump to operate. SANITIZATION-- The application of any effective method or substance to a clean surface for the destruction of pathogens, and of other organisms as far as is practicable. Such treatment must not adversely affect the equipment , the milk or milk product or the health of consumers. Sanitization may be accomplished by either the application of heat or suitable chemicals used in accordance with good manufacturing practices. SAFETY THERMAL LIMIT CONTROLLER-- The term sometimes used interchangeably when referring to the recorder-controller. SOLENOID-- An electronically operated valve used in various air controlling applications on continuous pasteurizers. STUFFING PUMP-- Any centrifugal pump used in the system for the purposes of enhancing product flow to a component, other that those located between the balance tank and the raw regenerator. TIME DELAY RELAY (TDR)-- An adjustable timer(either mechanical or electronically controlled) used to maintain a set time period equal to or greater than the required minimum. All required TDR&#039;s must be sealed by the regulatory agency. TIMING PUMP-- Sanitary , positive displacement -type (rotary or piston) or in the case of meter based systems a centrifugal product pump, which provides a constant measured rate of flow to the continuous pasteurization system. TURBULENT FLOW-- Flow where considerable mixing occurs across a pipe cross section and the velocity is nearly the same across this section. Turbulent flow occurs most frequently in less viscous liquids and is often characterized by higher friction losses than would be expected. VACUUM BREAKER-- An air relief valve held in the closed position by product flow pressures and which opens and admits air when the product pressure goes "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "ATMOSPHERIC PRESSURE-- The force exerted on an area by the column of air above that area. Atmospheric pressure at sea level is 14.7 pounds per square inch." } } </script> <a class="addthis_button_twitter"></a> <a class="addthis_button_email"></a> <a class="addthis_button_compact"></a> </div> <div class="clearfix text-formatted field field--name-body field--type-text-with-summary field--label-hidden field__item"><p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>ATMOSPHERIC PRESSURE<br /><strong>--</strong> The force exerted on an area by the column of air above that area. Atmospheric pressure at sea level is 14.7 pounds per square inch.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>BALANCE TANK<br /><strong>--</strong> Raw product tank located at the start of a pasteurization system used to maintain a constant supply of product to the pasteurizer.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>BOOSTER PUMP<br /><strong>--</strong> A centrifugal pump placed in a pasteurizing system between the balance tank and the raw regenerator and capable of producing positive pressure in the raw regenerator.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>BOURDON COIL (spring)<br /><strong>--</strong> A sealed flat metal tube filled with a gas mixture that has been formed into a coiled spiral, located inside the recorder-controller. This spiral expands or contracts in response to the vapor pressure of the gas mixture. This coil is located on one end of the capillary tube with the recorder-controller temperature sensing bulb at the other.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>CAPILLARY TUBE<br /><strong>--</strong> A thin metal tube, containing a mixture of liquids with low vapor pressures, that connects the bourdon tube in the recorder-controller with the temperature sensor bulb located at the flow diversion device. This thin tube is usually protected by a flexible metal cable.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>CENTRIFUGAL PUMP<br /><strong>--</strong> A high speed pump that produces product flow due to the velocity increase of the liquid caused by the rotation of the pump impeller.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>CONSTANT LEVEL TANK<br /><strong>--</strong> See Balance Tank.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>COOLING SECTION<br /><strong>--</strong> The section of a heat exchanger (press) in which one of several non-toxic coolants flows in a counter current direction on the opposite side of a stainless steel plate of the pasteurized product.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>DEFLECTOR PLATE<br /><strong>--</strong> A stainless steel plate in the regenerator section of the press designed to change the direction of flow.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>FLOW DIVERSION DEVICE<br /><strong>--</strong> Either a single stem (one three-way valve) or dual stem device (two, three-way valves connected by a common yoke), designed to change the direction of product flow when working in conjunction with the recorder-controller. (FDD)</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>FLOW CONTROLLER<br /><strong>--</strong> An instrument used in meter based systems which compares the flow signal from the flow transmitter to a set point and either controls the centrifugal pump speed or regulates a flow control valve downstream of the meter and centrifugal pump.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>FLOW TRANSMITTER<br /><strong>--</strong> An instrument used in meter based systems which converts signals from the magnetic flow meter to a 4- 20ma current.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>FREQUENCY PEN<br /><strong>--</strong> A solenoid actuated recording pen (located on the outer edge of the recording chart) that records the position of the flow diversion device in a continuous flow pasteurization system. This pen on a meter based system only records the flow diversion device position that has been electronically signaled by the flow recorder/controller.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>HEAT EXCHANGER<br /><strong>--</strong> Equipment designed to effect heat transfer between two or more mediums.(plate type, triple tubes, etc.).</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>HOLDING TUBE<br /><strong>--</strong> The section of piping in continuous flow pasteurizers of sufficient length to provide the minimum legal residence time for heated milk.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>HOT WATER TEMPERATURE CONTROLLER<br /><strong>--</strong> A system which controls the temperature of the heating medium by regulating a mixture of steam and water that circulates through the heating section of the press.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>I/P TRANSDUCER<br /><strong>--</strong> An instrument used in a meter based system that converts a 4-20ma current signal to an air signal (usually 15-30 psi) which drives the flow recorder pen</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>LAMINAR FLOW<br /><strong>--</strong> The movement of high viscosity products through a pipe in concentric layers where the fastest particle may move at twice the speed of the average particle</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>METERING PUMP<br /><strong>--</strong> See Timing Pump</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>PNEUMATIC<br /><strong>--</strong> Operated by compressed air.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>REGENERATOR BY-PASS VALVE<br /><strong>--</strong> A automatic or manually controlled valve used in combination with the booster pump for the purposes of start up of a continuous pasteurizer with a milk to milk regenerator. This valve allows for by-passing the regenerator in order to provide the proper pressure relationships in the regenerator, thus allowing the booster pump to operate.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>SANITIZATION<br /><strong>--</strong> The application of any effective method or substance to a clean surface for the destruction of pathogens, and of other organisms as far as is practicable. Such treatment must not adversely affect the equipment , the milk or milk product or the health of consumers. Sanitization may be accomplished by either the application of heat or suitable chemicals used in accordance with good manufacturing practices.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>SAFETY THERMAL LIMIT CONTROLLER<br /><strong>--</strong> The term sometimes used interchangeably when referring to the recorder-controller.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>SOLENOID<br /><strong>--</strong> An electronically operated valve used in various air controlling applications on continuous pasteurizers.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>STUFFING PUMP<br /><strong>--</strong> Any centrifugal pump used in the system for the purposes of enhancing product flow to a component, other that those located between the balance tank and the raw regenerator.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>TIME DELAY RELAY (TDR)<br /><strong>--</strong> An adjustable timer(either mechanical or electronically controlled) used to maintain a set time period equal to or greater than the required minimum. All required TDR's must be sealed by the regulatory agency.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>TIMING PUMP<br /><strong>--</strong> Sanitary , positive displacement -type (rotary or piston) or in the case of meter based systems a centrifugal product pump, which provides a constant measured rate of flow to the continuous pasteurization system.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>TURBULENT FLOW<br /><strong>--</strong> Flow where considerable mixing occurs across a pipe cross section and the velocity is nearly the same across this section. Turbulent flow occurs most frequently in less viscous liquids and is often characterized by higher friction losses than would be expected.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>VACUUM BREAKER<br /><strong>--</strong> An air relief valve held in the closed position by product flow pressures and which opens and admits air when the product pressure goes</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> </div> <div class="field field--name-field-sf-article-category field--type-entity-reference field--label-above"> <div class="field__label">Category</div> <div class="field__item"><a href="/articles/dairy-processing/dairy-processing-information" hreflang="en">Dairy Processing Information</a></div> </div> Thu, 22 Jun 2017 23:01:48 +0000 Anonymous 411 at https://drinc.ucdavis.edu Milk Flavors https://drinc.ucdavis.edu/dairy-processing/milk-flavors <span class="field field--name-title field--type-string field--label-hidden">Milk Flavors</span> <span class="field field--name-uid field--type-entity-reference field--label-hidden"> <span lang="" typeof="schema:Person" property="schema:name" datatype=""> (not verified)</span> </span> <span class="field field--name-created field--type-created field--label-hidden">June 22, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-processing.rss" addthis:title="Dairy Processing" addthis:description="Flavor in one of the most important qualities that determine the acceptability of milk. Even though milk is highly nutritious, people will not drink it if they do not like it. Hence, milk should be produced under conditions that give good flavor initially, and also be handled to protect its flavor at every step from the cow to the consumer. As population densities increase around large metropolitan centers, milk is usually transported longer distances to supply the urban population, and the farms located near the cities tend to increase their scale of operations. Both changes may influence milk&#039;s initial flavor and particularly its flavor stability. Transporting milk longer distances usually increases the time between production and processing, which provides a greater opportunity for development of off-flavors. To maintain bacteriological quality during this extended storage period, greater emphasis is placed on improved sanitary practices and effective refrigeration. Defects of bacterial origin are generally kept under control, but the changes may result in an increased incidence of other defects. For example, as dairying became more intensive, bulk collection systems were introduced. They provided for cooling milk to lower storage temperatures, and when couple with longer storage times, oxidized and rancid flavors could develop. When the average number of cows in herds increases, farmers have to provide a larger proportion of the cow&#039;s feed in dry form as hay and concentrate, instead of as pasture and silage. In general, dry feeds yield milk with greater susceptibility to oxidized and rancid flavors than do succulent feeds. Feeding high levels of concentrate, as practiced in intensive dairy areas, increases the concentration of unsaturated fatty acids in milk lipids, with an accompanying increase in liability of the fat to oxidation. As distribution channels are equipped to provide more effective refrigeration of milk during delivery to stores and homes, and during storage in retail outlets, processors extend the expected shelf-life of their products. For example, a Californian company dates the products it packages in paper containers for expected &#039;shelf-life&#039; of 12 days in distribution channels, and extends its tests in the quality control laboratory for an additional week. Thus, it is not sufficient to produce milk with good flavor initially. Increasing attention is being given to the stability of milk flavor during storage. NORMAL MILK FLAVOR Milk of good quality is a very bland food with a slightly sweet taste, very little odor, and a smooth, rich feel in the mouth. Because of its bland flavor, the presence of minute quantities of abnormal constituents frequently results in off-flavors. Dairy producers and processors have, of necessity, been so concerned with the control of off-flavors, that until recently little attention has been given lower temperatures than prevailed with can collection systems. Most people associate the palatability of milk with its &#039;richness&#039;. It is generally assumed that milk fat is one of the most important constituents in contributing to the desirable flavor of milk. Although there is a close correlation between the concentration of fat and solids- not-fat in milk as produced by the cow, little attention has been given to the contribution of the solids-not- fat constituents to its flavor. In studies conducted in the 1960s, tests were made to determine the minimum difference in the concentration of selected milk constituents that could be detected reasonably consistently (two times out of three) by a trained laboratory panel. Special care was taken in the preparation of the milk samples to avoid any abnormal flavors that might have influenced detection of differences. In homogenized milk of typical commercial composition (3.5 % fat and 8.0 % S.N.F.), the percentage of fat had to be increased by more than S.N.F (i.e. to over 9 %) before the panel could differentiate it from the control milk two times out of three, whereas the S.N.F. had to be increased by only O.6% for comparable differentiation. This result indicates that a small increase in S.N.F. would have a greater influence on milk flavor than a comparable increase in fat. The experiments were extended to study the roles of individual constituents or fractions of S.N.F. An increase of O.33% lactose was detected two times out of three. A concentrate of non-dialysable constituents of skim milk (mainly protein) was prepared by dialyzing concentrated skim milk against normal skim milk, and this concentrate was used to increase the concentration of protein and other colloidal constituents in milk. An increase of 2.S% of non-dialysable constituents (2.2% of the increase as proteins) was needed for two-thirds correct detection. Thus, lactose appears to be important, and the proteins relatively unimportant, in contributing to the normal flavor of milk. The increasing sales in the United States and Canada of milk products containing increased S.N.F. concentrations indicate that these products have acceptable flavor. Products containing 2% fat and 10% S.N.F. are widely distributed and are gaining in popularity. Skim milk with a normal S.N.F. concentration has never been popular, but non fat products with increased S.N.F. have developed into successful commercial products. Cows&#039; milk is a palatable beverage, but nature did not develop it to appeal to man&#039;s taste. We should not limit ourselves to using milk as nature produces it for the calf. To increase milk sales, we should take advantage of modern technology to modify milk to man&#039;s taste and nutritional requirements. OFF-FLAVORS IN MILK AS PRODUCED Feed and weed flavors In many countries the most common flavor defect of milk is feed flavor. The incidence in different countries is hard to assess because evaluations are based only on subjective judgments, and opinions regarding the intensity of the off-flavor that constitutes a defect are very variable. Likewise, levels that are objectionable to consumers are equally variable. The presence of feed or weed flavors in a high proportion of milk samples in a number of surveys indicates that the off-flavors may be detected by, and are presumably objectionable to, many consumers. Understanding the mode of transmission of flavor substances in the cow&#039;s body assists practical control of feed flavors. The respiratory system and the digestive tract are both important in transmitting flavor substances to the milk odors from some feeds pass into the cow&#039;s blood from air in the lungs, and are then carried to the udder and appears. in the milk. Some flavor-producing substances are absorbed by the blood from the digestive tract, and are then transmitted to the udder. For some feeds, both the respiratory and digestive tracts are involved in the transmission of flavor to milk. Some feeds, such as garlic and onion, release volatile flavors after partial digestion in the rumen. odors belched from the rumen are inhaled into the lungs and transferred to the blood. This pathway provides a more rapid transfer of feed flavors from ingested feed than direct absorption from the digestive tract. Fortunately, blood provides a two-way street for transportation of feed flavors. When the concentration of the flavor substances is higher in the milk in the udder than in the blood, the substances transfer from the milk to the blood. If sufficient time is allowed after the feed is consumed, the flavor substances are eliminated from the blood, partly by transfer of volatile substances to the air in the lung, and partly by metabolism of the substances. In either case, they are eliminated from the cow&#039;s body. The time interval between eating and milking is an important factor influencing the intensity of feed flavors. Whether the off-flavor resulted from only breathing the odor of silage, or from eating the silage, the feed flavor was most pronounced from 2 to 3 hr. later, but had been eliminated from the milk 5 hr. later. These results show why feeds commonly used in dairy rations will not cause objectionable flavors if they are fed after milking, and withheld from the cows during the 4-5 hr. before milking. Not all feeds respond to flavor control. Some flavor substances accumulate in cow body tissues, particularly in the fat. They then transfer to the blood, and hence to the milk, over long periods of time. one of the most lingering flavor defects reported resulted from eating potatoes grown on a field treated with benzene hexachloride (for nematode control). A mothball-like flavor was still detectable in the milk three weeks after this feed was discontinued. Flavors from some weeds persist for longer than 12 hr. after they are eaten, and therefore such weeds must be kept out of a cow&#039;s ration. In selecting feeds for a dairy ration, one criterion must be that either the feed does not impart an undesirable flavor to milk, or the flavor can be controlled by withholding the feed for a reasonable time before milking. It is impracticable to withhold feed for more than 5 hr., as prod production will suffer. Flavors from many feeds can be controlled by withholding the feed 2-4 hr. before milking. Reports on some feeds and their effect on milk flavor are inconsistent. For example, sugar beets, beet pulp, and beet tops do not normally cause objectionable flavors, but are sometimes responsible for fishy flavor. The difficulty appears to be sporadic, varying with each individual cow and with different lots of feed. The quantity of feed consumed, its quality, and in some cases its maturity, may influence its flavor- producing characteristics. Many weeds cause off-flavors in milk. Weeds are variable in their effects. Flavors caused by some can be controlled if the weeds are withheld from the cow 5 hr. before milking. The off-flavor from some weeds (onion, penny cress) appears principally in the milk fat, whereas that from others (bitterweed) is associated with the skim milk portion. The defect may be more pronounced with young plants (cocklebur) or with older plants or their seeds (penny cress). In most cases the off-flavor is present when milk is drawn from the cow, but this is not always true. For example, skunkweed flavor does not appear in fresh milk or cream, but shows up in butter or cheese. Wild carrot eaten alone sometimes produces a mild off- flavor, but when eaten along with mule&#039;s tail or mare&#039;s tail, the skunkweed defect becomes pronounced. The scorched flavor caused by swine cress is evident only after milk or cream is heated. on the other hand, pasteurization markedly reduces or changes the character of other feed flavors. The ensiling process destroys the substances causing ragweed and pepper grass flavors but does not affect the substances causing onion flavor. Such inconsistencies in the influence of different feeds and weeds on flavor indicate the danger of making general statements regarding their behavior. Since odoriferous substances are volatile, attention has been given to developing practical procedures for removing them by vaporization. The value of using aerators or surface coolers as a means of reducing feed flavors is often overrated. When alfalfa-flavored milk cooled over a surface cooler was compared with the same milk cooled in a container, experienced judges had difficulty in detecting consistently the sample with supposedly less feed flavor. Although aeration may cause some reduction in the intensity of some feed flavors, it cannot be relied on to control the defect. In recent years many liquid milk processors in the United States and Canada have installed equipment that subjects milk to a combined vacuum and heat treatment to remove volatile flavors. The effectiveness of such equipment depends not only on the intensity of the treatment, but also on the nature and concentration of the flavor substances. Some flavor treating machines are very effective, whereas others have little influence on milk. Use of flavor-removing equipment can provide the processor with an extra safeguard in protecting the flavor quality of the milk he sells, but present indications are that the producer will still have to take the major responsibility for control of feed flavors by sound management practices. Cowy, barny and unclean favors These terms describe flavors that are attributable to unsatisfactory production conditions, but there are several possible causes. one of the most common is inhalation by the cows of foul air in poorly-ventilated barns or corrals in which wet manure has accumulated. The barny, unclean odors are transferred to the milk through the cow&#039;s respiratory system in the same manner as for feed flavors. Although direct absorption of the odors by milk during and after milking is frequently mentioned as a possible cause, research has established that this source is insignificant compared with absorption through the cow&#039;s respiratory tract. Metabolic disturbances of the cow may also result in cowy and other unclean flavors. Ketosis is frequently accompanied by cowy flavor. Cows with the disease have a high concentration of acetone bodies in their blood. These compounds appear in the milk and are at least partly responsible for the cowy flavor. Other conditions that upset the cow&#039;s d digestive processes have also been associated with cowy and other undesirable flavors. Mastitis reduces the flavor quality of milk, but the effects are variable. Mild cases may result in a flat flavor, probably due to a lower concentration of the normal milk constituents. In more severe cases of mastitis, the milk is usually criticized for cowy, unclean, and salty flavors. In some cases cowy, barny and unclean flavors may be attributable to the cow&#039;s feed. Some weeds cause the appearance in milk of indole and skatole compounds that give the characteristic odor to faces. Abnormal silage fermentations may also result in unclean flavors in milk. Although cowy flavor is listed as a defect present in milk as drawn from the cow, the flavor may intensify during storage. The increased intensity may be due to increased concentrations of acetone and butanone, but nothing has been reported regarding the source of and conditions influencing the appearance of these compounds during storage. Foreign and chemical flavors Some flavors that are present immediately after milking may be caused by chemical contamination. Treatment of teats with salve is a possible source of medicinal flavor. Equipment used in handling milk may also contribute off-flavors, such as the phenolic taste from certain plastics, or chemical tastes from sanitizing agents used to treat milking equipment. Combinations of chemical contaminants may be more troublesome than one alone, as illustrated by difficulties encountered by some dairy producers and processors with chlorophenol flavor. Phenolic and chlorine compounds in combination can, in certain circumstances, be detected at lower concentrations than either alone, because they may react to form chlorophenols. Salty taste Salty taste is caused by two conditions: mastitis and advanced lactation. The defect is rarely detected in pooled milks, because only a small proportion of cows would produce salty milk in a well-managed herd. Nevertheless, salty milk should be eliminated from the supply, because it is detrimental to milk quality. Milk that has excellent flavor as produced may develop objectionable defects before it reaches the consumer. Recent changes in the dairy industry have caused changes in the flavor problems encountered. In the early days of the market milk industry, when sanitation practices were inadequate and relatively few refrigerators were available in homes, defects caused by bacteria, such as sour flavor, limited the time that milk remained usable. Today such bacterial defects are encountered less frequently because of modern sanitation practices, improved refrigeration and transportation facilities, and widespread adoption of pasteurization. Defects caused by chemical changes during storage such as oxidized and rancid flavors make up a larger percentage of observed defects than formerly. Milk as purchased is now more uniform in flavor and defective product is more likely to result in a complaint than in former years. Hence, processors must pay more attention to improving both the initial flavor and the flavor stability of milk during its expected usable life. Oxidized flavors Oxidized flavor is a troublesome defect of non-homogenized milk, skim milk, cream, and certain other dairy products. The flavor is described by terms so various as metallic, papery, cardboardy, oily, and tallowy, indicating the great variability of the predominant flavor characteristic. The defect is caused by the oxidation of fatty constituents in the product. Knowledge of the milk constituents that are involved in the development of oxidized flavor, or influence susceptibility of milk to the defect, helps one to understand the factors that influence the flavor. The compounds responsible for the flavor are produced by oxidation of unsaturated fatty acids in the phospholipids in the membrane surrounding the fat globules. Conditions are more conducive to oxidation at the surface than inside the fat globules for at least four reasons: (1) The phospholipids, which are concentrated at the surface lace, contain a higher proportion of unsaturated fatty acids than the remainder of the fat globule; (2) The oxidation catalyst, copper, is also concentrated at the surface of the fat globule; (3) oxygen from air dissolves in the skim milk portion of milk, and thereby reaches the surface of the fat globules; (4) The ascorbic acid in milk, which is also dissolved in the skim milk portion, is an important pro-oxidant in normal milk, even though it can also act as an antioxidant. As a counter effect, at least one important natural anti-oxidant, tocopherol, is concentrated in the material at the surface of the fat globules. Thus, the susceptibility of milk to oxidized flavor depends on the balance between the pro-oxidant and anti-oxidant factors at the surface of the globule. The milk processor can take advantage of two processes that prevent or delay development of oxidized flavor: homogenization and heat treatment. The oxidative stability of milk (its ability to resist oxidized flavor) is determined to a large extent at the farm. For this reason, in recent years the main efforts to control oxidized flavor have been concentrated on the point of production. Milk varies greatly in its susceptibility to oxidized flavor. The variability is particularly evident when the milks of individual cows are compared. Some milks develop oxidized flavor without any treatment other than refrigerated storage for as little as one day. others are so resistant that even if 5 p.p.m. of copper are added they do not develop oxidized flavor in seven days of storage. Obviously, this extreme variability is important in determining whether oxidized flavor will develop in milk and what measures must be taken to control the defect. One of the most important factors influencing the oxidative stability of milk is the cows&#039; feed. Pasture and other succulent feeds generally yield milk that is very resistant to oxidized flavor. The defect is encountered most frequently with dry feeds. Changes in some feeding practices in order to increase production per cow appear to be increasing the susceptibility of milk to oxidized flavor. In the United States, during seasons when the milk is susceptible to oxidized flavor, some dairymen select feeds containing high concentrations of tocopherol, or supplement rations with tocopherol to increase the oxidative stability of the milk. The oxidative stability of milk is also influenced by some other conditions related to the cow, such as heredity, number of lactations and stage of lactation. It is helpful to recognize that such variables influence oxidized flavor, even though they cannot be manipulated to control the defect. The cow has a marked influence on the initial oxidative stability of milk, but virtually every treatment milk receives between the cow and the consumer influences, in one way or another, the development of oxidized flavor. Low storage temperatures favor the development of oxidized flavor. This effect is contrary to that expected of chemical reactions. Two explanations of this behavior relate to retarding the growth of bacteria, and reducing the activity of the natural anti-oxidants in milk, but they have not been supported by experimental evidence. Storing milk at low temperatures is encouraged to maintain high bacterial quality, even though it may aggravate problems with oxidized flavor. It also frequently results in longer storage times. Thus, the adoption of mechanical refrigeration for cooling milk, particularly in bulk tanks, has sometimes been accompanied by an increased incidence of oxidized flavor in milk. A common serious cause of oxidized flavor is contamination of milk with copper. The role of metals, especially copper, in catalyzing oxidized flavor has been recognized for many years. Tinned-copper equipment has been largely replaced by 18-8 type stainless steel for the manufacture of most dairy equipment. nickel-copper alloys, commonly called &#039;white metal&#039; or &#039;stainless metal; have been substituted for stainless steel to reduce costs, but this is an unsatisfactory compromise. White metal introduces appreciable copper contamination to milk. Copper bearing alloys must be eliminated from the cleaning circuits, as well as from milk-contact surfaces of equipment, otherwise copper will dissolve from the copper-bearing metals during circulation cleaning, and deposit on stainless steel. This copper is then picked up by the first milk that passes through the equipment after cleaning. Another serious cause of oxidized flavor in many countries is exposure of milk to light, particularly during distribution in clear glass bottles. This may induce either oxidized flavor, or a light-activated flavor, or both. The two defects differ chemically, but in many respects the effects are similar. They are discussed in greater detail in the section dealing with light activated flavor. Regardless whether the defect is predominantly oxidized or light-activated flavor, or both, the obvious control is to protect milk from exposure to light. Pasteurization slightly increases the susceptibility of milk to oxidized flavor. Milk pasteurized at temperature-time combinations that do not seriously impair creaming properties usually develops oxidized flavor more rapidly than non-pasteurized milk. More severe heat treatments, however, reduce susceptibility, apparently both by producing anti-oxidants and by reducing the catalytic activity of copper. Treatments that produce a cooked or heated flavor usually delay development of oxidized flavor. Products such as the non-fat pasteurized milk enriched with solids-not-fat, which is common in the United States, are usually pasteurized at temperatures appreciably above the minimum required for pasteurization (e.g. at 180-185 F for 20 sec. or longer) in order to help control oxidized flavor. Homogenization markedly increases the resistance of milks to oxidized flavor. Many explanations have been given for this effect, but none has been supported by convincing experimental evidence. The inhibiting effect is so pronounced that homogenized milk rarely develops oxidized flavor. The popularity of homogenized milk in the United States and Canada is attributed largely to its superior flavor because of the practical control of oxidized flavor provided by homogenization. De-aeration has been suggested to prevent development of oxidized flavor. De-aerating equipment is available that effectively removes dissolved oxygen from milk and thereby delays or prevents the defect. Unfortunately, the process is of little value commercially, because most of the bottle and carton fillers in common use allow enough oxygen to redissolve in milk to produce oxidized flavor. Several other methods of inhibiting oxidized flavor are not useful in control programs, either because they are not permitted by present regulations, or because they are detrimental to other quality characteristics of milk. Many anti-oxidants effectively prevent oxidized flavor when added to milk, but in most countries their use is not permitted. There are statements in the literature that bacteria growing in milk retard oxidized flavor, either by using up dissolved oxygen necessary for the oxidative reactions, or by producing anti-oxidants. Partially hydrolyzed proteins have anti-oxidant properties, so proteolytic activity of bacteria could also indirectly retard oxidized flavor. However, the numbers of bacteria necessary to retard development of oxidized flavor are very large (generally over 1 million/mL.). Hence, variations in the smaller numbers of bacteria normally found in milks that meet legal standards would not be of practical importance in determining whether milk develops oxidized flavor. Light-activated flavors Light-activated flavor results from chemical changes in protein when milk is exposed to light. other names by which the defect has been identified include sunshine, sunlight, and solar activated. Terms used to describe the flavor are cabbage, burnt, burnt feather, burnt protein, and mushroom. Because light may induce either oxidized or light-activated flavor, or both, some investigators have not differentiated clearly between the two defects. This has resulted in confusion regarding similarities and differences between them. Several characteristics of light-activated flavor aid in understanding conditions that influence its development and methods for its control. Homogenized milk is susceptible to light-activated flavor, but resistant to oxidized flavor. Light-activated flavor increases with intensity and duration of exposure, and the predominant flavor characteristic changes during exposure and subsequent storage. The temperature of the milk during exposure and storage is also critical. Higher exposure temperatures (50-60 F) result in more pronounced flavor, but the flavor of samples exposed at low temperatures (35-40 F) may increase in intensity for several hours after exposure. If, after exposure, the milk is held at higher-than-normal refrigeration temperatures (e.g. 50-60 F), the flavor may decrease in intensity. The time interval between homogenization and exposure also has an influence. If milk is stored one or more days after homogenization, but before exposure, it is much less susceptible to the defect. Light of the shorter wavelengths (blue and green) has greater effect than that of longer wavelengths (yellow and red). Fluorescent light is more troublesome than incandescent light, because it usually has a higher proportion of its energy in light of short wavelengths. Also, because fluorescent lamps are not hot, milk is frequently placed close to them in retail display cases. Selecting fluorescent lamps that emit a high proportion of the &#039;warm&#039; tones helps to minimize damage from fluorescent light in display cases. Likewise, use of colored bottles or paper containers that absorb much of the light of shorter wavelengths provides protection, but does not necessarily prevent activated flavor under very adverse conditions. The cows&#039; feed influences light activated flavor as it does oxidized flavor. Green feeds appear to yield milks with greatest resistance to the defect. Hence, as for oxidized flavor, the susceptibility of milk to light activated flavor varies seasonal]y and is greatest during the winter. Rancid flavor The term &#039;rancid&#039;, when applied to milk and other dairy foods, refers to a flavor defect caused by hydrolysis of fat, rather than by oxidation of fat. Milk always contains an enzyme (or a group of enzymes) known as lipase, which is able under certain conditions to hydrolyze fat, splitting off fatty acids that are responsible for the rancid flavor. Freshly drawn milk from healthy cows is never rancid. Depending on conditions, rancidity may develop on aging of raw milk. Pasteurization destroys lipase, so properly pasteurized milk will not go rancid. In most milks, the so-called &#039;membrane&#039; around the fat globules appears to protect the fat from attack by lipase. Certain treatments, known as activating treatments, change the fat globule surface sufficiently to permit the lipase to act on the milk lipids and produce rancid flavor. Three activating treatments that may be encountered in milk production and processing are (1) agitation of warm milk, particularly under conditions that produce foam; (2) homogenization of raw milk (or mixing raw and homogenized milk); and (3) temperature fluctuations such as cooling milk, warming it to about 86 F and then cooling it again. When milk samples from individual cows are cooled and stored one or two days, a small proportion of the samples may develop rancid flavor. This rancidity is sometimes referred to as spontaneous, because no treatment other than cooling is required for its development. Some investigators believe spontaneous rancidity is caused by a lipase which differs from that present in normal milk, whereas others consider that the fat globules of &#039;spontaneous&#039; milk do not have sufficient protective matter on their surfaces to prevent attack by lipase. Regardless of the explanation, spontaneous rancidity is not a serious source of off-flavor in commercial milk supplies. It occurs most commonly with milk from low-producing cows that are very advanced in lactation and should be dried off. Also, if milk from such cows is mixed with non- spontaneous milk, the mixture usually does not develop rancid flavor unless it receives an activating treatment. Hence, when rancidity is encountered in commercial milk, the immediate cause is usually an activating treatment. Susceptibility of milk to induced rancidity varies greatly. Rancid flavor of differing intensity develops in milk samples taken from individual cows in a herd, and even from individual quarters of a cow&#039;s udder. Individual cows show marked daily variations in susceptibility of their milk. Susceptibility is often greater when cows are in advanced lactation. Green succulent feeds make milk more resistant than dry feeds. The numerous variables that influence susceptibility are at least partly responsible for sporadic and seasonal variations in incidence of rancidity. To achieve labor efficiencies, the producer adopted the bulk collection system and changed from bucket milkers to pipeline milking systems. The average number of cows on dairy farms increased, and to increase milk yield per cow farmers depended more and more on feeding hay and concentrate mixtures. These progressive developments seriously aggravated rancid flavor problems. The change is not attributable to a single cause, but to a combination of changes that took place simultaneously. When the bulk tank system was adopted, it was possible to cool milk more rapidly and store it at lower temperatures than with the can system. Rancid flavor induced by some activating treatments develops more rapidly as the storage temperature is decreased. In some instances, defective or inadequate refrigeration systems resulted in prolonged agitation of warm milk, or temperature fluctuations resulting from additions of warm milk to previously cooled milk. In some districts, milk was collected only on alternate days, resulting in longer storage which favored the development of rancidity. When new installations were made, most were entirely of stainless steel in the milk-contact areas. This eliminated sources of contaminating metals. The lipase in milk is unstable in conditions that favor oxidation. Thus, eliminating copper contamination, added to the rapid cooling of milk, increased the stability of the lipase. Many early installations of pipeline milkers provided conditions which subjected milk to activating treatments. Milk was commonly elevated in vertical sections of the vacuum line by bubbling air through it. Excessive amounts of air entered the systems at milker claws, fittings, etc. Pumps were operated continuously, but starved. Low producing cows in advanced lactation were not so readily detected and were retained in the milking strings too long. As the number of cows per herd was increased, farmers could no longer supply enough pasture or silage for the cows. Hay and grain concentrate mixtures provided increasing proportions of the nutrients for milk production, and these dry feeds yielded milk with greater susceptibility to rancidity. All of the above conditions probably contributed to rancid flavor problems. To control the defect, many unsatisfactory practices and equipment installations have been eliminated. Although most commercial milk is undoubtedly more susceptible to rancidity than that produced in pre-war years, the industry has learned to cope with the problem by minimizing activating conditions. As noted above, pasteurization, by inactivating the lipase, provides the processor with a very effective method of controlling rancidity. High susceptibility of milk to rancidity may limit flexibility of operations in a processing plant by necessitating prompt pasteurization to prevent development of rancidity. In properly pasteurized milk, rancid flavor should not be a problem. Processing plant employees must be aware of conditions that may induce rancidity. If cooled milk is warmed for separation, the cream should not be cooled again without being pasteurized. Homogenized milk must be pasteurized before, or immediately after homogenization Homogenized products should not be mixed with raw products. Prolonged agitation of warm raw milk (80-120 F) or pumping it through starved pumps may induce rancidity. Heated flavors In commercial processing, milk is almost invariably subjected to heat treatments at least as severe as the minimum required for pasteurization, and frequently more severe. In general, the intensity of the heated flavor increases with that of the heat treatment. Pasteurization produces a slight heated or cooked flavor in milk. This process is used so widely that most consumers consider a slight heated flavor to be typical of normal milk and they do not find it objectionable. A slight heated flavor contributes to the apparent sweetness and richness of milk masks some off-flavors of low intensity, and may make milk less susceptible to oxidized flavor. For these reasons, some processors deliberately use pasteurization temperatures appreciably in excess of the legal minimum to produce a slight heated flavor in the freshly pasteurized milk. This flavor decreases in intensity during storage. Hence, although uniformity is desirable, the intensity of the heated flavor does not remain constant during the time milk is in distribution channels. Heat treatments at much higher temperatures and for longer times than required for pasteurization are used in the processing of many dairy products, and they produce pronounced heated flavors with differing predominant characteristics. The first that becomes evident results from liberation from the proteins of hydrogen sulfide and other sulfides. More severe heat treatments give scorched and burnt flavors caused by more extensive changes in the proteins; caramel flavors attributable to reactions involving lactose; and lactone or; coconut-like flavors resulting from changes in the milk fats. These more severe heat treatments are accompanied by changes in the tactile. or mouth-feel, characteristics of milk. Such flavors are typical of sterilized milks, and are objectionable to most consumers. Hence, extensive research has been directed toward sterilizing milk without producing the objectionable flavor caused by conventional sterilizing treatments. Bacterial flavors Off-flavors caused by the growth of bacteria in milk are not detectable until large numbers of bacteria are present, usually millions per milliliter. Hence, the milk would not meet legal standards for bacterial quality. Nevertheless, defects caused by bacteria are encountered from time to time, and it is important to know their characteristics and conditions under which they develop. Milk is such a good food for bacteria, as it is for man, that it is very subject to spoilage. It must be rigorously protected from bacterial contamination, and kept cold to minimize growth of bacteria that are present. If flavors of bacterial origin develop in raw milk, this indicates that sanitary practices have been inadequate, or that the milk has been held at too high a temperature, or too long. A sour, high acid, or malty flavor may result if raw milk is held at temperatures above 45 F. At lower temperatures, the flavors that develop are usually caused by psychrophilic bacteria and are described as fruity, bitter, rancid or putrid. Pasteurization destroys the milk souring bacteria so effectively that, when pasteurized milk spoils from microbial growth, the cause is usually bacteria that contaminate the milk after pasteurization. Thus, the keeping quality of pasteurized milk stored at 45 F or below can serve as an indication of sanitary practices in the plant. As for raw milk, the psychrophilic organisms that grow at these low temperatures cause fruity, bitter. rancid or putrid flavors. Properly pasteurized milk, adequately protected from post- pasteurization contamination and stored at 45 F, should resist psychrophilic spoilage for at least two weeks. MILK FLAVOR QUALITY CONTROL Flavor Quality Control Some of the more common off-flavors that may be present in milk as it comes from the cow or may develop during processing and storage were discussed in the first two papers in this series. Understanding the nature of desirable and undesirable flavors in milk, and conditions that influence these flavors, provides a sound basis for an effective flavor control program. In addition, not only quality control personnel, but also milk producers and processors, can benefit materially by familiarizing themselves with techniques for flavor perception and evaluation, and by developing proficiency in identifying the common off-flavors of milk. Preparing Milk Samples The first important step in a flavor control program is the technique for collecting and preparing milk samples. Commercially processed milk in its consumer package usually serves as a satisfactory sample and container. The products must be protected from light, refrigerated during transport, and either examined promptly or stored at a standardized temperature before examination. Milk samples that must be collected from bulk containers or individual cows pose special problems. Frequently, the method of treating the sample must be adapted to the flavor defect that is being studied. For most purposes, milk bottles (usually a quart) are satisfactory and conveniently available. Bottles with rubber closures should be avoided as the rubber may impart foreign flavors to the milk. Polyethylene bottles with polyethylene screw caps are very satisfactory. They are light and durable, withstand heat shocks of laboratory pasteurization, and may be autoclaved if desired. For studies of oxidized flavor, they have an additional advantage over glass they adsorb less copper that would otherwise contaminate the samples. Raw milk should be pasteurized before it is tasted, but the time and method depend on the defect. For many purposes, the milk should be pasteurized immediately and examined while fresh and again after a standardized storage treatment. Pasteurization, however, prevents the development of rancidity by inactivating the lipase. If rancidity is of concern, the milk should be stored raw for at least two days and then pasteurized before the flavor examination. on the other hand, if the greatest concern is with oxidized flavor, the milk should be pasteurized before storage to prevent the development of rancidity and bacterial flavors that might otherwise mask oxidized flavor. Pasteurization of flavor samples in accordance with legal definitions is not practicable. Samples may be pasteurized in their containers by heating and cooling them in a water bath, with a thermometer in a reference bottle containing the same volume of milk as the sample bottles. Shaking the bottles provides adequate agitation. The containers should be closed to minimize volatilization of feed flavors. The temperature-time combination used should produce little or no heated flavor, yet provide protection from disease and be convenient for the equipment available. If a thermostatically controlled agitated water bath is used, heating to 145 F for 30 min. is satisfactory; otherwise a combination such as 150 F for 4 min. or 161 F with no holding period is more convenient. It is difficult to recognize flavors from descriptions. Hence, it is important to practice identifying the most common defects by repeatedly tasting samples with known flavors. The procedures outlined below are suggested as convenient methods for preparing samples having typical flavor defects. Feed or Weed flavor Where facilities permit, it is best to feed an individual cow feeds or weeds known to cause characteristic flavors (e.g. silage) 1 to 2 hr. before milking, then collect the milk from this cow. In processing plants it is usually possible to select milk with feed flavor from individual producers during receiving operations. Samples prepared by soaking feeds in milk do not usually give typical defects. Oxidized flavor Place a strip of bare sheet copper or 1 ft. of coiled copper wire in a bottle of pasteurized milk (not homogenized) and store in refrigerator one or two days. Unless the milk is unusually resistant, oxidized flavor will develop. Light-activated flavor Light-activated flavor is usually evident in freshly processed homogenized milk exposed to sunlight for 2 hr. in quart glass bottles, and then held in a refrigerator for at least 4 hr. Homogenized milk is preferred because it is more susceptible]e to light activated flavor and less susceptible to oxidized flavor than non- homogenized milk. Adding ascorbic acid (50 mg. /quart) before exposure enhances light-activated flavor but inhibits oxidized flavor. Rancid flavor Mix equal volumes of raw milk and homogenized milk and store in refrigerator overnight. If rancidity is not evident, heat to 70-90 F and hold. Taste at hourly intervals until the desired intensity develops, then pasteurized rise. Salty flavor The best way to obtain a typical salty flavor in milk is to examine samples from individual cows and select one with the defect. Salty flavored milk is produced most frequently in advanced lactation or when the cow has mastitis. Heated flavorP&gt; Heat milk to a temperature higher than is normally used for pasteurization, such as 170 F for two min., and cool. EVALUATING MILK FLAVOR Understanding how we perceive flavors aids in flavor evaluation. Flavor is a blend of sensations from several sensory organs. The most important sensations contributing to milk&#039;s flavor are the taste, smell and feel. Taste is detected in the mouth, principally on the tongue. There are only four tastes—sweet, sour, salt and bitter. To produce a taste sensation, a substance must be in solution in order to diffuse into the receptor sites in the taste buds. Odor is detected by olfactory nerves in the nasal passages. The number of odors is almost limitless, and many are difficult to describe. To have an odor a substance must be volatile. Most compounds with strong odors are more soluble in fat than in water, whereas the reverse is true of most substances with pronounced tastes. Another sensation that contributes to flavor is the way the food feels in the mouth. Some tactile characteristics of milk are smoothness, chalkiness, and richness attributable to consistency. Although most milk is drunk cold, warming milk enhances its odor and facilitates detection of off-flavors. For quality control evaluations, milk usually warmed to about 70 F. The bottle should be shaken, the cap removed and the sample smelled. A head space above the milk (e.g. bottle two-thirds full) aids in evaluating odors. Next, the sample should be tasted. The milk should be moved around in the mouth to contact all portions, particularly of the tongue, and to promote volatilization of compounds that contribute to the odor. Particular attention should be given to the changing sensations with time. Sweet, sour and salty tastes are usually detected quickly, whereas bitter tastes become evident more slowly but are retained longer. The most important step in learning to evaluate milk flavor is to gain proficiency in identifying defects. Correct identification provides helpful guidelines for control of defects. Evaluating the intensity of defects, however, is also of value in quality control programs. Many different systems for designating intensity of flavors are in use. In some, intensity is indicated only by descriptive terms such as slight, distinct or strong, or by one, two or three plus signs. A simple numerical system applies scores for these descriptive terms: 0, no criticism; 1, slight; 2, distinct; and 3, strong. An inverse of this scale, or one giving a higher maximum score for flavor, such as 5 or 10 points, is preferable for quality scoring as it recognizes higher quality with a higher score. Any numerical system is arbitrary, but there is an advantage in selecting one that is in common use. In the United States a system that is widely used assigns scores within the range 10 for good milk to 0 for poor milk. TROUBLE-SHOOTING FLAVOR DEFECTS If an off-flavor is found in a milk sample, a systematic approach helps in identifying the defect and its cause. An experienced individual will identify the most common off-flavors of milk by taste, and will be able to proceed immediately to determine the most probable cause. A beginner in flavor quality control work will be guided in his identification of off-flavors by comparing defective samples with samples having known off-flavors prepared as described above. Changes in intensity of a defect during storage provide helpful evidence regarding its identity. Hence, samples should be tasted fresh and again after storage in a refrigerator for at least 48 hr. RAW MILK To pin-point possible causes of off-flavors in raw milk, it is helpful to collect milk samples at different steps. Samples might be collected from individual cows, at the discharge from the pipeline milker, from individual cans or the bulk tank, from the tank after only one milking and later at the time the milk is collected, or from morning and evening milkings separately. If an off-flavor is present in a fresh sample collected from pooled raw milk, it is usually attributable to feed. In some cases, there may be a marked difference between morning and evening milk in intensity of the off-flavor. Examining the feeds for known troublesome materials may substantiate suspicions regarding possible causes. Recommendations for corrective measures include: Use only feeds that cause little or no feed flavor. Eliminate weeds from pastures and from crops to be used for hay or concentrates. Arrange feeding schedule to Prevent the cows from eating feeds that may cause off-flavors during the 4-5 hr. before milking. Provide an environment where the cow can breathe fresh air free of feedy, cowy or barny odors. Individual cows in a herd may produce milk with an off-flavor when it is drawn, such as a salty taste attributable to mastitis or advanced lactation, or a cowy flavor caused by ketosis. It is rare that such defects can be identified in the mixed milk from the entire herd, but they make the pooled supply less palatable. Therefore, milk from such cows should be withheld from the pooled milk. In some instances, the cow may appear to be responsible for off-flavors that are actually caused by equipment, or treatment of the cow or equipment. Examples are a medicinal flavor from salves used on the teats or udder, or chlorophenol flavor from plastic or rubber parts of the milking equipment. If an off-flavor is not present in fresh milk, but develops during storage, possible identities are light activated, oxidized, rancid and microbial flavors. Light-activated is the least likely in raw milk, and in any case its cause and correction would be immediately apparent. Comparison with reference samples aids in differentiating between oxidized and rancid flavors. Also, pasteurization of the fresh sample prevents development of rancid and bacterial flavors but not oxidized flavor. Some microbial flavors caused by psychrophilic bacteria are difficult to differentiate from rancid flavor because the bacteria produce lipolytic enzymes that release fatty acids, and also proteolytic enzymes that yield degradation products from protein with similar flavors. Information from bacterial counts of the milk, inspection of equipment, and checking on sanitizing procedures and cooling practices indicates whether bacterial flavors may be involved. If the defect appears to be rancid flavor, a chemical test for free fatty acids could be used for confirmation. Rancidity that occurs in raw milk supplies usually is induced by an activating treatment: either excessive agitation of warm milk or temperature fluctuations between 50 and 86 F. Eliminating the activating condition usually prevents development of the defect. Determining the susceptibility of milk from individual cows is also helpful. Cows that produce the most susceptible milk are usually in advanced lactation, and there is little loss in production resulting from drying them off. In correcting problems with oxidized flavor. If samples taken from individual cows indicate that a high proportion of the cows in the herd are producing milk in which the defect develops without metal contamination, the most practical control would be through the herd ration. PASTEURIZED MILK In &#039;trouble-shooting&#039; causes of defects in processed milk, samples should be collected from the raw milk storage tanks and at every step in processing where feasible. A good practice is to compare &#039;first-off&#039; samples with samples collected near the end of a processing run. If product from one processing line feeds several fillers, samples should be taken from each filler. As for raw milk, the samples should be tasted fresh and after storage, except that a storage period of at least a week is preferable for most pasteurized products. Identification of the defect, using prepared reference samples for comparison if necessary, is the first step toward effective control. Corrective measures for the most common defects were indicated in the first two papers in this series, and are summarized briefly here. Limited shelf-life resulting from bacterial growth is usually caused by post-pasteurization contamination. Phosphatase tests may be run on freshly pasteurized products to check on adequacy of pasteurization. The unclean, fruity, bitter and putrid flavors that develop in pasteurized milk are usually attributable to growth of psychrophilic bacteria that do not survive pasteurization. Hence, critical evaluation of cleaning and sanitizing procedures is necessary in order to detect sources of post-pasteurization contamination. Checks on temperature and time of storage, and rotation of stock should also be included. Rancid flavor should not develop in a properly pasteurized product, but activating treatments at some stage of processing may induce its development before pasteurization. Possible causes include mixing pasteurized homogenized products with raw milk, warming cooled milk to about 85 F and recooling, and excessive agitation and foaming of raw milk. If the intensity of the flavor increases during storage, the possibility that the milk was improperly pasteurized or was contaminated by raw milk should be checked by use of the phosphatase test. Problems with oxidized flavor may be caused primarily by low oxidative stability of the milk as produced, but are aggravated by abuse at any stage of processing and distribution. Particular attention should be given to avoiding copper contamination from white metal and other copper-containing alloys, and to minimizing exposure to light. Use of higher pasteurizing temperatures may be helpful if the more severe heat treatment does not produce objectionable heated flavors. Milk that is susceptible to oxidized flavor may be directed into homogenized products, as homogenization inhibits oxidized flavor. Locating causes of some atypical flavors in processed milk is sometimes a baffling assignment, even for people with extensive experience in flavor-control work. The approaches outlined above, however, provide guides to step-by-step elimination of possible causes of a defect. CONCLUSION The objective of quality control personnel should be more than to prevent customer complaints. Routine daily examination of all processed products, fresh and after storage, usually results in recognition of off- flavors before they reach such intensity that they become objectionable to consumers. Much of the pasteurized milk sold today could be made more palatable by selecting milk of high quality initially, and giving increased attention to protecting its flavor during processing and distribution. Maintaining consumer confidence in the dependable high quality of milk is essential for maximum consumption. Adapted by John C. Bruhn from articles written by: Professor Emeritus W. L. Dunkley and John C. Bruhn, University of California,  Department Food Science and Technology,  UC Davis,  Davis, CA 95616-8598 March 1995 "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "Flavor in one of the most important qualities that determine the acceptability of milk. Even though milk is highly nutritious, people will not drink it if they do not like it. Hence, milk should be produced under conditions that give good flavor initially, and also be handled to protect its flavor at every step from the cow to the consumer." } } </script> <a class="addthis_button_twitter"></a> <a class="addthis_button_email"></a> <a class="addthis_button_compact"></a> </div> <div class="clearfix text-formatted field field--name-body field--type-text-with-summary field--label-hidden field__item"><p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Flavor in one of the most important qualities that determine the acceptability of milk. Even though milk is highly nutritious, people will not drink it if they do not like it. Hence, milk should be produced under conditions that give good flavor initially, and also be handled to protect its flavor at every step from the cow to the consumer.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>As population densities increase around large metropolitan centers, milk is usually transported longer distances to supply the urban population, and the farms located near the cities tend to increase their scale of operations. Both changes may influence milk's initial flavor and particularly its flavor stability. Transporting milk longer distances usually increases the time between production and processing, which provides a greater opportunity for development of off-flavors. To maintain bacteriological quality during this extended storage period, greater emphasis is placed on improved sanitary practices and effective refrigeration. Defects of bacterial origin are generally kept under control, but the changes may result in an increased incidence of other defects. For example, as dairying became more intensive, bulk collection systems were introduced. They provided for cooling milk to lower storage temperatures, and when couple with longer storage times, oxidized and rancid flavors could develop.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>When the average number of cows in herds increases, farmers have to provide a larger proportion of the cow's feed in dry form as hay and concentrate, instead of as pasture and silage. In general, dry feeds yield milk with greater susceptibility to oxidized and rancid flavors than do succulent feeds. Feeding high levels of concentrate, as practiced in intensive dairy areas, increases the concentration of unsaturated fatty acids in milk lipids, with an accompanying increase in liability of the fat to oxidation.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>As distribution channels are equipped to provide more effective refrigeration of milk during delivery to stores and homes, and during storage in retail outlets, processors extend the expected shelf-life of their products. For example, a Californian company dates the products it packages in paper containers for expected 'shelf-life' of 12 days in distribution channels, and extends its tests in the quality control laboratory for an additional week. Thus, it is not sufficient to produce milk with good flavor initially. Increasing attention is being given to the stability of milk flavor during storage.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h3><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>NORMAL MILK FLAVOR</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h3> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Milk of good quality is a very bland food with a slightly sweet taste, very little odor, and a smooth, rich feel in the mouth. Because of its bland flavor, the presence of minute quantities of abnormal constituents frequently results in off-flavors. Dairy producers and processors have, of necessity, been so concerned with the control of off-flavors, that until recently little attention has been given lower temperatures than prevailed with can collection systems. Most people associate the palatability of milk with its 'richness'. It is generally assumed that milk fat is one of the most important constituents in contributing to the desirable flavor of milk. Although there is a close correlation between the concentration of fat and solids- not-fat in milk as produced by the cow, little attention has been given to the contribution of the solids-not- fat constituents to its flavor.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>In studies conducted in the 1960s, tests were made to determine the minimum difference in the concentration of selected milk constituents that could be detected reasonably consistently (two times out of three) by a trained laboratory panel. Special care was taken in the preparation of the milk samples to avoid any abnormal flavors that might have influenced detection of differences. In homogenized milk of typical commercial composition (3.5 % fat and 8.0 % S.N.F.), the percentage of fat had to be increased by more than S.N.F (i.e. to over 9 %) before the panel could differentiate it from the control milk two times out of three, whereas the S.N.F. had to be increased by only O.6% for comparable differentiation. This result indicates that a small increase in S.N.F. would have a greater influence on milk flavor than a comparable increase in fat.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>The experiments were extended to study the roles of individual constituents or fractions of S.N.F. An increase of O.33% lactose was detected two times out of three. A concentrate of non-dialysable constituents of skim milk (mainly protein) was prepared by dialyzing concentrated skim milk against normal skim milk, and this concentrate was used to increase the concentration of protein and other colloidal constituents in milk. An increase of 2.S% of non-dialysable constituents (2.2% of the increase as proteins) was needed for two-thirds correct detection. Thus, lactose appears to be important, and the proteins relatively unimportant, in contributing to the normal flavor of milk.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>The increasing sales in the United States and Canada of milk products containing increased S.N.F. concentrations indicate that these products have acceptable flavor. Products containing 2% fat and 10% S.N.F. are widely distributed and are gaining in popularity. Skim milk with a normal S.N.F. concentration has never been popular, but non fat products with increased S.N.F. have developed into successful commercial products.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Cows' milk is a palatable beverage, but nature did not develop it to appeal to man's taste. We should not limit ourselves to using milk as nature produces it for the calf. To increase milk sales, we should take advantage of modern technology to modify milk to man's taste and nutritional requirements.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h3><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>OFF-FLAVORS IN MILK AS PRODUCED</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h3> <h4><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Feed and weed flavors</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h4> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>In many countries the most common flavor defect of milk is feed flavor. The incidence in different countries is hard to assess because evaluations are based only on subjective judgments, and opinions regarding the intensity of the off-flavor that constitutes a defect are very variable. Likewise, levels that are objectionable to consumers are equally variable. The presence of feed or weed flavors in a high proportion of milk samples in a number of surveys indicates that the off-flavors may be detected by, and are presumably objectionable to, many consumers.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Understanding the mode of transmission of flavor substances in the cow's body assists practical control of feed flavors. The respiratory system and the digestive tract are both important in transmitting flavor substances to the milk odors from some feeds pass into the cow's blood from air in the lungs, and are then carried to the udder and appears. in the milk. Some flavor-producing substances are absorbed by the blood from the digestive tract, and are then transmitted to the udder. For some feeds, both the respiratory and digestive tracts are involved in the transmission of flavor to milk. Some feeds, such as garlic and onion, release volatile flavors after partial digestion in the rumen. odors belched from the rumen are inhaled into the lungs and transferred to the blood. This pathway provides a more rapid transfer of feed flavors from ingested feed than direct absorption from the digestive tract.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Fortunately, blood provides a two-way street for transportation of feed flavors. When the concentration of the flavor substances is higher in the milk in the udder than in the blood, the substances transfer from the milk to the blood. If sufficient time is allowed after the feed is consumed, the flavor substances are eliminated from the blood, partly by transfer of volatile substances to the air in the lung, and partly by metabolism of the substances. In either case, they are eliminated from the cow's body.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>The time interval between eating and milking is an important factor influencing the intensity of feed flavors. Whether the off-flavor resulted from only breathing the odor of silage, or from eating the silage, the feed flavor was most pronounced from 2 to 3 hr. later, but had been eliminated from the milk 5 hr. later. These results show why feeds commonly used in dairy rations will not cause objectionable flavors if they are fed after milking, and withheld from the cows during the 4-5 hr. before milking.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Not all feeds respond to flavor control. Some flavor substances accumulate in cow body tissues, particularly in the fat. They then transfer to the blood, and hence to the milk, over long periods of time. one of the most lingering flavor defects reported resulted from eating potatoes grown on a field treated with benzene hexachloride (for nematode control). A mothball-like flavor was still detectable in the milk three weeks after this feed was discontinued.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Flavors from some weeds persist for longer than 12 hr. after they are eaten, and therefore such weeds must be kept out of a cow's ration. In selecting feeds for a dairy ration, one criterion must be that either the feed does not impart an undesirable flavor to milk, or the flavor can be controlled by withholding the feed for a reasonable time before milking. It is impracticable to withhold feed for more than 5 hr., as prod production will suffer. Flavors from many feeds can be controlled by withholding the feed 2-4 hr. before milking.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Reports on some feeds and their effect on milk flavor are inconsistent. For example, sugar beets, beet pulp, and beet tops do not normally cause objectionable flavors, but are sometimes responsible for fishy flavor. The difficulty appears to be sporadic, varying with each individual cow and with different lots of feed. The quantity of feed consumed, its quality, and in some cases its maturity, may influence its flavor- producing characteristics.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Many weeds cause off-flavors in milk. Weeds are variable in their effects. Flavors caused by some can be controlled if the weeds are withheld from the cow 5 hr. before milking. The off-flavor from some weeds (onion, penny cress) appears principally in the milk fat, whereas that from others (bitterweed) is associated with the skim milk portion. The defect may be more pronounced with young plants (cocklebur) or with older plants or their seeds (penny cress). In most cases the off-flavor is present when milk is drawn from the cow, but this is not always true. For example, skunkweed flavor does not appear in fresh milk or cream, but shows up in butter or cheese. Wild carrot eaten alone sometimes produces a mild off- flavor, but when eaten along with mule's tail or mare's tail, the skunkweed defect becomes pronounced. The scorched flavor caused by swine cress is evident only after milk or cream is heated. on the other hand, pasteurization markedly reduces or changes the character of other feed flavors. The ensiling process destroys the substances causing ragweed and pepper grass flavors but does not affect the substances causing onion flavor. Such inconsistencies in the influence of different feeds and weeds on flavor indicate the danger of making general statements regarding their behavior.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Since odoriferous substances are volatile, attention has been given to developing practical procedures for removing them by vaporization. The value of using aerators or surface coolers as a means of reducing feed flavors is often overrated. When alfalfa-flavored milk cooled over a surface cooler was compared with the same milk cooled in a container, experienced judges had difficulty in detecting consistently the sample with supposedly less feed flavor. Although aeration may cause some reduction in the intensity of some feed flavors, it cannot be relied on to control the defect.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>In recent years many liquid milk processors in the United States and Canada have installed equipment that subjects milk to a combined vacuum and heat treatment to remove volatile flavors. The effectiveness of such equipment depends not only on the intensity of the treatment, but also on the nature and concentration of the flavor substances. Some flavor treating machines are very effective, whereas others have little influence on milk. Use of flavor-removing equipment can provide the processor with an extra safeguard in protecting the flavor quality of the milk he sells, but present indications are that the producer will still have to take the major responsibility for control of feed flavors by sound management practices.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h4><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Cowy, barny and unclean favors</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h4> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>These terms describe flavors that are attributable to unsatisfactory production conditions, but there are several possible causes. one of the most common is inhalation by the cows of foul air in poorly-ventilated barns or corrals in which wet manure has accumulated. The barny, unclean odors are transferred to the milk through the cow's respiratory system in the same manner as for feed flavors. Although direct absorption of the odors by milk during and after milking is frequently mentioned as a possible cause, research has established that this source is insignificant compared with absorption through the cow's respiratory tract.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Metabolic disturbances of the cow may also result in cowy and other unclean flavors. Ketosis is frequently accompanied by cowy flavor. Cows with the disease have a high concentration of acetone bodies in their blood. These compounds appear in the milk and are at least partly responsible for the cowy flavor. Other conditions that upset the cow's d digestive processes have also been associated with cowy and other undesirable flavors.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Mastitis reduces the flavor quality of milk, but the effects are variable. Mild cases may result in a flat flavor, probably due to a lower concentration of the normal milk constituents. In more severe cases of mastitis, the milk is usually criticized for cowy, unclean, and salty flavors. In some cases cowy, barny and unclean flavors may be attributable to the cow's feed. Some weeds cause the appearance in milk of indole and skatole compounds that give the characteristic odor to faces. Abnormal silage fermentations may also result in unclean flavors in milk.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Although cowy flavor is listed as a defect present in milk as drawn from the cow, the flavor may intensify during storage. The increased intensity may be due to increased concentrations of acetone and butanone, but nothing has been reported regarding the source of and conditions influencing the appearance of these compounds during storage.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h4><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Foreign and chemical flavors</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h4> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Some flavors that are present immediately after milking may be caused by chemical contamination. Treatment of teats with salve is a possible source of medicinal flavor. Equipment used in handling milk may also contribute off-flavors, such as the phenolic taste from certain plastics, or chemical tastes from sanitizing agents used to treat milking equipment. Combinations of chemical contaminants may be more troublesome than one alone, as illustrated by difficulties encountered by some dairy producers and processors with chlorophenol flavor. Phenolic and chlorine compounds in combination can, in certain circumstances, be detected at lower concentrations than either alone, because they may react to form chlorophenols.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h4><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Salty taste</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h4> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Salty taste is caused by two conditions: mastitis and advanced lactation. The defect is rarely detected in pooled milks, because only a small proportion of cows would produce salty milk in a well-managed herd. Nevertheless, salty milk should be eliminated from the supply, because it is detrimental to milk quality.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Milk that has excellent flavor as produced may develop objectionable defects before it reaches the consumer. Recent changes in the dairy industry have caused changes in the flavor problems encountered. In the early days of the market milk industry, when sanitation practices were inadequate and relatively few refrigerators were available in homes, defects caused by bacteria, such as sour flavor, limited the time that milk remained usable. Today such bacterial defects are encountered less frequently because of modern sanitation practices, improved refrigeration and transportation facilities, and widespread adoption of pasteurization. Defects caused by chemical changes during storage such as oxidized and rancid flavors make up a larger percentage of observed defects than formerly. Milk as purchased is now more uniform in flavor and defective product is more likely to result in a complaint than in former years. Hence, processors must pay more attention to improving both the initial flavor and the flavor stability of milk during its expected usable life.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h4><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Oxidized flavors</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h4> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Oxidized flavor is a troublesome defect of non-homogenized milk, skim milk, cream, and certain other dairy products. The flavor is described by terms so various as metallic, papery, cardboardy, oily, and tallowy, indicating the great variability of the predominant flavor characteristic. The defect is caused by the oxidation of fatty constituents in the product. Knowledge of the milk constituents that are involved in the development of oxidized flavor, or influence susceptibility of milk to the defect, helps one to understand the factors that influence the flavor. The compounds responsible for the flavor are produced by oxidation of unsaturated fatty acids in the phospholipids in the membrane surrounding the fat globules. Conditions are more conducive to oxidation at the surface than inside the fat globules for at least four reasons: (1) The phospholipids, which are concentrated at the surface lace, contain a higher proportion of unsaturated fatty acids than the remainder of the fat globule; (2) The oxidation catalyst, copper, is also concentrated at the surface of the fat globule; (3) oxygen from air dissolves in the skim milk portion of milk, and thereby reaches the surface of the fat globules; (4) The ascorbic acid in milk, which is also dissolved in the skim milk portion, is an important pro-oxidant in normal milk, even though it can also act as an antioxidant. As a counter effect, at least one important natural anti-oxidant, tocopherol, is concentrated in the material at the surface of the fat globules. Thus, the susceptibility of milk to oxidized flavor depends on the balance between the pro-oxidant and anti-oxidant factors at the surface of the globule.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>The milk processor can take advantage of two processes that prevent or delay development of oxidized flavor: homogenization and heat treatment. The oxidative stability of milk (its ability to resist oxidized flavor) is determined to a large extent at the farm. For this reason, in recent years the main efforts to control oxidized flavor have been concentrated on the point of production.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Milk varies greatly in its susceptibility to oxidized flavor. The variability is particularly evident when the milks of individual cows are compared. Some milks develop oxidized flavor without any treatment other than refrigerated storage for as little as one day. others are so resistant that even if 5 p.p.m. of copper are added they do not develop oxidized flavor in seven days of storage. Obviously, this extreme variability is important in determining whether oxidized flavor will develop in milk and what measures must be taken to control the defect.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>One of the most important factors influencing the oxidative stability of milk is the cows' feed. Pasture and other succulent feeds generally yield milk that is very resistant to oxidized flavor. The defect is encountered most frequently with dry feeds. Changes in some feeding practices in order to increase production per cow appear to be increasing the susceptibility of milk to oxidized flavor. In the United States, during seasons when the milk is susceptible to oxidized flavor, some dairymen select feeds containing high concentrations of tocopherol, or supplement rations with tocopherol to increase the oxidative stability of the milk.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>The oxidative stability of milk is also influenced by some other conditions related to the cow, such as heredity, number of lactations and stage of lactation. It is helpful to recognize that such variables influence oxidized flavor, even though they cannot be manipulated to control the defect.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>The cow has a marked influence on the initial oxidative stability of milk, but virtually every treatment milk receives between the cow and the consumer influences, in one way or another, the development of oxidized flavor.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Low storage temperatures favor the development of oxidized flavor. This effect is contrary to that expected of chemical reactions. Two explanations of this behavior relate to retarding the growth of bacteria, and reducing the activity of the natural anti-oxidants in milk, but they have not been supported by experimental evidence. Storing milk at low temperatures is encouraged to maintain high bacterial quality, even though it may aggravate problems with oxidized flavor. It also frequently results in longer storage times. Thus, the adoption of mechanical refrigeration for cooling milk, particularly in bulk tanks, has sometimes been accompanied by an increased incidence of oxidized flavor in milk.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>A common serious cause of oxidized flavor is contamination of milk with copper. The role of metals, especially copper, in catalyzing oxidized flavor has been recognized for many years. Tinned-copper equipment has been largely replaced by 18-8 type stainless steel for the manufacture of most dairy equipment. nickel-copper alloys, commonly called 'white metal' or 'stainless metal; have been substituted for stainless steel to reduce costs, but this is an unsatisfactory compromise. White metal introduces appreciable copper contamination to milk. Copper bearing alloys must be eliminated from the cleaning circuits, as well as from milk-contact surfaces of equipment, otherwise copper will dissolve from the copper-bearing metals during circulation cleaning, and deposit on stainless steel. This copper is then picked up by the first milk that passes through the equipment after cleaning.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Another serious cause of oxidized flavor in many countries is exposure of milk to light, particularly during distribution in clear glass bottles. This may induce either oxidized flavor, or a light-activated flavor, or both. The two defects differ chemically, but in many respects the effects are similar. They are discussed in greater detail in the section dealing with light activated flavor. Regardless whether the defect is predominantly oxidized or light-activated flavor, or both, the obvious control is to protect milk from exposure to light.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Pasteurization slightly increases the susceptibility of milk to oxidized flavor. Milk pasteurized at temperature-time combinations that do not seriously impair creaming properties usually develops oxidized flavor more rapidly than non-pasteurized milk. More severe heat treatments, however, reduce susceptibility, apparently both by producing anti-oxidants and by reducing the catalytic activity of copper. Treatments that produce a cooked or heated flavor usually delay development of oxidized flavor. Products such as the non-fat pasteurized milk enriched with solids-not-fat, which is common in the United States, are usually pasteurized at temperatures appreciably above the minimum required for pasteurization (e.g. at 180-185 F for 20 sec. or longer) in order to help control oxidized flavor.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Homogenization markedly increases the resistance of milks to oxidized flavor. Many explanations have been given for this effect, but none has been supported by convincing experimental evidence. The inhibiting effect is so pronounced that homogenized milk rarely develops oxidized flavor. The popularity of homogenized milk in the United States and Canada is attributed largely to its superior flavor because of the practical control of oxidized flavor provided by homogenization.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>De-aeration has been suggested to prevent development of oxidized flavor. De-aerating equipment is available that effectively removes dissolved oxygen from milk and thereby delays or prevents the defect. Unfortunately, the process is of little value commercially, because most of the bottle and carton fillers in common use allow enough oxygen to redissolve in milk to produce oxidized flavor.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Several other methods of inhibiting oxidized flavor are not useful in control programs, either because they are not permitted by present regulations, or because they are detrimental to other quality characteristics of milk. Many anti-oxidants effectively prevent oxidized flavor when added to milk, but in most countries their use is not permitted. There are statements in the literature that bacteria growing in milk retard oxidized flavor, either by using up dissolved oxygen necessary for the oxidative reactions, or by producing anti-oxidants. Partially hydrolyzed proteins have anti-oxidant properties, so proteolytic activity of bacteria could also indirectly retard oxidized flavor. However, the numbers of bacteria necessary to retard development of oxidized flavor are very large (generally over 1 million/mL.). Hence, variations in the smaller numbers of bacteria normally found in milks that meet legal standards would not be of practical importance in determining whether milk develops oxidized flavor.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h4><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Light-activated flavors</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h4> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Light-activated flavor results from chemical changes in protein when milk is exposed to light. other names by which the defect has been identified include sunshine, sunlight, and solar activated. Terms used to describe the flavor are cabbage, burnt, burnt feather, burnt protein, and mushroom.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Because light may induce either oxidized or light-activated flavor, or both, some investigators have not differentiated clearly between the two defects. This has resulted in confusion regarding similarities and differences between them. Several characteristics of light-activated flavor aid in understanding conditions that influence its development and methods for its control.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Homogenized milk is susceptible to light-activated flavor, but resistant to oxidized flavor. Light-activated flavor increases with intensity and duration of exposure, and the predominant flavor characteristic changes during exposure and subsequent storage. The temperature of the milk during exposure and storage is also critical. Higher exposure temperatures (50-60 F) result in more pronounced flavor, but the flavor of samples exposed at low temperatures (35-40 F) may increase in intensity for several hours after exposure. If, after exposure, the milk is held at higher-than-normal refrigeration temperatures (e.g. 50-60 F), the flavor may decrease in intensity. The time interval between homogenization and exposure also has an influence. If milk is stored one or more days after homogenization, but before exposure, it is much less susceptible to the defect.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Light of the shorter wavelengths (blue and green) has greater effect than that of longer wavelengths (yellow and red). Fluorescent light is more troublesome than incandescent light, because it usually has a higher proportion of its energy in light of short wavelengths. Also, because fluorescent lamps are not hot, milk is frequently placed close to them in retail display cases.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Selecting fluorescent lamps that emit a high proportion of the 'warm' tones helps to minimize damage from fluorescent light in display cases. Likewise, use of colored bottles or paper containers that absorb much of the light of shorter wavelengths provides protection, but does not necessarily prevent activated flavor under very adverse conditions.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>The cows' feed influences light activated flavor as it does oxidized flavor. Green feeds appear to yield milks with greatest resistance to the defect. Hence, as for oxidized flavor, the susceptibility of milk to light activated flavor varies seasonal]y and is greatest during the winter.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h4><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Rancid flavor</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h4> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>The term 'rancid', when applied to milk and other dairy foods, refers to a flavor defect caused by hydrolysis of fat, rather than by oxidation of fat. Milk always contains an enzyme (or a group of enzymes) known as lipase, which is able under certain conditions to hydrolyze fat, splitting off fatty acids that are responsible for the rancid flavor. Freshly drawn milk from healthy cows is never rancid. Depending on conditions, rancidity may develop on aging of raw milk. Pasteurization destroys lipase, so properly pasteurized milk will not go rancid.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>In most milks, the so-called 'membrane' around the fat globules appears to protect the fat from attack by lipase. Certain treatments, known as activating treatments, change the fat globule surface sufficiently to permit the lipase to act on the milk lipids and produce rancid flavor. Three activating treatments that may be encountered in milk production and processing are (1) agitation of warm milk, particularly under conditions that produce foam; (2) homogenization of raw milk (or mixing raw and homogenized milk); and (3) temperature fluctuations such as cooling milk, warming it to about 86 F and then cooling it again.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>When milk samples from individual cows are cooled and stored one or two days, a small proportion of the samples may develop rancid flavor. This rancidity is sometimes referred to as spontaneous, because no treatment other than cooling is required for its development. Some investigators believe spontaneous rancidity is caused by a lipase which differs from that present in normal milk, whereas others consider that the fat globules of 'spontaneous' milk do not have sufficient protective matter on their surfaces to prevent attack by lipase. Regardless of the explanation, spontaneous rancidity is not a serious source of off-flavor in commercial milk supplies. It occurs most commonly with milk from low-producing cows that are very advanced in lactation and should be dried off. Also, if milk from such cows is mixed with non- spontaneous milk, the mixture usually does not develop rancid flavor unless it receives an activating treatment. Hence, when rancidity is encountered in commercial milk, the immediate cause is usually an activating treatment.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Susceptibility of milk to induced rancidity varies greatly. Rancid flavor of differing intensity develops in milk samples taken from individual cows in a herd, and even from individual quarters of a cow's udder. Individual cows show marked daily variations in susceptibility of their milk. Susceptibility is often greater when cows are in advanced lactation. Green succulent feeds make milk more resistant than dry feeds. The numerous variables that influence susceptibility are at least partly responsible for sporadic and seasonal variations in incidence of rancidity.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>To achieve labor efficiencies, the producer adopted the bulk collection system and changed from bucket milkers to pipeline milking systems. The average number of cows on dairy farms increased, and to increase milk yield per cow farmers depended more and more on feeding hay and concentrate mixtures. These progressive developments seriously aggravated rancid flavor problems. The change is not attributable to a single cause, but to a combination of changes that took place simultaneously.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>When the bulk tank system was adopted, it was possible to cool milk more rapidly and store it at lower temperatures than with the can system. Rancid flavor induced by some activating treatments develops more rapidly as the storage temperature is decreased. In some instances, defective or inadequate refrigeration systems resulted in prolonged agitation of warm milk, or temperature fluctuations resulting from additions of warm milk to previously cooled milk. In some districts, milk was collected only on alternate days, resulting in longer storage which favored the development of rancidity.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>When new installations were made, most were entirely of stainless steel in the milk-contact areas. This eliminated sources of contaminating metals. The lipase in milk is unstable in conditions that favor oxidation. Thus, eliminating copper contamination, added to the rapid cooling of milk, increased the stability of the lipase.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Many early installations of pipeline milkers provided conditions which subjected milk to activating treatments. Milk was commonly elevated in vertical sections of the vacuum line by bubbling air through it. Excessive amounts of air entered the systems at milker claws, fittings, etc. Pumps were operated continuously, but starved. Low producing cows in advanced lactation were not so readily detected and were retained in the milking strings too long.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>As the number of cows per herd was increased, farmers could no longer supply enough pasture or silage for the cows. Hay and grain concentrate mixtures provided increasing proportions of the nutrients for milk production, and these dry feeds yielded milk with greater susceptibility to rancidity.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>All of the above conditions probably contributed to rancid flavor problems. To control the defect, many unsatisfactory practices and equipment installations have been eliminated. Although most commercial milk is undoubtedly more susceptible to rancidity than that produced in pre-war years, the industry has learned to cope with the problem by minimizing activating conditions.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>As noted above, pasteurization, by inactivating the lipase, provides the processor with a very effective method of controlling rancidity. High susceptibility of milk to rancidity may limit flexibility of operations in a processing plant by necessitating prompt pasteurization to prevent development of rancidity. In properly pasteurized milk, rancid flavor should not be a problem.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Processing plant employees must be aware of conditions that may induce rancidity. If cooled milk is warmed for separation, the cream should not be cooled again without being pasteurized. Homogenized milk must be pasteurized before, or immediately after homogenization Homogenized products should not be mixed with raw products. Prolonged agitation of warm raw milk (80-120 F) or pumping it through starved pumps may induce rancidity.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h4><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Heated flavors</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h4> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>In commercial processing, milk is almost invariably subjected to heat treatments at least as severe as the minimum required for pasteurization, and frequently more severe. In general, the intensity of the heated flavor increases with that of the heat treatment.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Pasteurization produces a slight heated or cooked flavor in milk. This process is used so widely that most consumers consider a slight heated flavor to be typical of normal milk and they do not find it objectionable. A slight heated flavor contributes to the apparent sweetness and richness of milk masks some off-flavors of low intensity, and may make milk less susceptible to oxidized flavor. For these reasons, some processors deliberately use pasteurization temperatures appreciably in excess of the legal minimum to produce a slight heated flavor in the freshly pasteurized milk. This flavor decreases in intensity during storage. Hence, although uniformity is desirable, the intensity of the heated flavor does not remain constant during the time milk is in distribution channels.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Heat treatments at much higher temperatures and for longer times than required for pasteurization are used in the processing of many dairy products, and they produce pronounced heated flavors with differing predominant characteristics. The first that becomes evident results from liberation from the proteins of hydrogen sulfide and other sulfides. More severe heat treatments give scorched and burnt flavors caused by more extensive changes in the proteins; caramel flavors attributable to reactions involving lactose; and lactone or; coconut-like flavors resulting from changes in the milk fats. These more severe heat treatments are accompanied by changes in the tactile. or mouth-feel, characteristics of milk. Such flavors are typical of sterilized milks, and are objectionable to most consumers. Hence, extensive research has been directed toward sterilizing milk without producing the objectionable flavor caused by conventional sterilizing treatments.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h4><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Bacterial flavors</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h4> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Off-flavors caused by the growth of bacteria in milk are not detectable until large numbers of bacteria are present, usually millions per milliliter. Hence, the milk would not meet legal standards for bacterial quality. Nevertheless, defects caused by bacteria are encountered from time to time, and it is important to know their characteristics and conditions under which they develop.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Milk is such a good food for bacteria, as it is for man, that it is very subject to spoilage. It must be rigorously protected from bacterial contamination, and kept cold to minimize growth of bacteria that are present. If flavors of bacterial origin develop in raw milk, this indicates that sanitary practices have been inadequate, or that the milk has been held at too high a temperature, or too long.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>A sour, high acid, or malty flavor may result if raw milk is held at temperatures above 45 F. At lower temperatures, the flavors that develop are usually caused by psychrophilic bacteria and are described as fruity, bitter, rancid or putrid.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Pasteurization destroys the milk souring bacteria so effectively that, when pasteurized milk spoils from microbial growth, the cause is usually bacteria that contaminate the milk after pasteurization. Thus, the keeping quality of pasteurized milk stored at 45 F or below can serve as an indication of sanitary practices in the plant. As for raw milk, the psychrophilic organisms that grow at these low temperatures cause fruity, bitter. rancid or putrid flavors. Properly pasteurized milk, adequately protected from post- pasteurization contamination and stored at 45 F, should resist psychrophilic spoilage for at least two weeks.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h3><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>MILK FLAVOR QUALITY CONTROL</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h3> <h4><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Flavor Quality Control</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h4> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Some of the more common off-flavors that may be present in milk as it comes from the cow or may develop during processing and storage were discussed in the first two papers in this series. Understanding the nature of desirable and undesirable flavors in milk, and conditions that influence these flavors, provides a sound basis for an effective flavor control program. In addition, not only quality control personnel, but also milk producers and processors, can benefit materially by familiarizing themselves with techniques for flavor perception and evaluation, and by developing proficiency in identifying the common off-flavors of milk.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h4><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Preparing Milk Samples</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h4> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>The first important step in a flavor control program is the technique for collecting and preparing milk samples. Commercially processed milk in its consumer package usually serves as a satisfactory sample and container. The products must be protected from light, refrigerated during transport, and either examined promptly or stored at a standardized temperature before examination.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Milk samples that must be collected from bulk containers or individual cows pose special problems. Frequently, the method of treating the sample must be adapted to the flavor defect that is being studied.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>For most purposes, milk bottles (usually a quart) are satisfactory and conveniently available. Bottles with rubber closures should be avoided as the rubber may impart foreign flavors to the milk. Polyethylene bottles with polyethylene screw caps are very satisfactory. They are light and durable, withstand heat shocks of laboratory pasteurization, and may be autoclaved if desired. For studies of oxidized flavor, they have an additional advantage over glass they adsorb less copper that would otherwise contaminate the samples.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Raw milk should be pasteurized before it is tasted, but the time and method depend on the defect. For many purposes, the milk should be pasteurized immediately and examined while fresh and again after a standardized storage treatment. Pasteurization, however, prevents the development of rancidity by inactivating the lipase. If rancidity is of concern, the milk should be stored raw for at least two days and then pasteurized before the flavor examination. on the other hand, if the greatest concern is with oxidized flavor, the milk should be pasteurized before storage to prevent the development of rancidity and bacterial flavors that might otherwise mask oxidized flavor.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Pasteurization of flavor samples in accordance with legal definitions is not practicable. Samples may be pasteurized in their containers by heating and cooling them in a water bath, with a thermometer in a reference bottle containing the same volume of milk as the sample bottles. Shaking the bottles provides adequate agitation. The containers should be closed to minimize volatilization of feed flavors. The temperature-time combination used should produce little or no heated flavor, yet provide protection from disease and be convenient for the equipment available. If a thermostatically controlled agitated water bath is used, heating to 145 F for 30 min. is satisfactory; otherwise a combination such as 150 F for 4 min. or 161 F with no holding period is more convenient.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>It is difficult to recognize flavors from descriptions. Hence, it is important to practice identifying the most common defects by repeatedly tasting samples with known flavors. The procedures outlined below are suggested as convenient methods for preparing samples having typical flavor defects.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h4><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Feed or Weed flavor</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h4> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Where facilities permit, it is best to feed an individual cow feeds or weeds known to cause characteristic flavors (e.g. silage) 1 to 2 hr. before milking, then collect the milk from this cow. In processing plants it is usually possible to select milk with feed flavor from individual producers during receiving operations. Samples prepared by soaking feeds in milk do not usually give typical defects.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h4><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Oxidized flavor</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h4> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Place a strip of bare sheet copper or 1 ft. of coiled copper wire in a bottle of pasteurized milk (not homogenized) and store in refrigerator one or two days. Unless the milk is unusually resistant, oxidized flavor will develop.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h4><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Light-activated flavor</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h4> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Light-activated flavor is usually evident in freshly processed homogenized milk exposed to sunlight for 2 hr. in quart glass bottles, and then held in a refrigerator for at least 4 hr. Homogenized milk is preferred because it is more susceptible]e to light activated flavor and less susceptible to oxidized flavor than non- homogenized milk. Adding ascorbic acid (50 mg. /quart) before exposure enhances light-activated flavor but inhibits oxidized flavor.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h4><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Rancid flavor</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h4> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Mix equal volumes of raw milk and homogenized milk and store in refrigerator overnight. If rancidity is not evident, heat to 70-90 F and hold. Taste at hourly intervals until the desired intensity develops, then pasteurized rise.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h4><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Salty flavor</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h4> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>The best way to obtain a typical salty flavor in milk is to examine samples from individual cows and select one with the defect. Salty flavored milk is produced most frequently in advanced lactation or when the cow has mastitis.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Heated flavorP&gt; Heat milk to a temperature higher than is normally used for pasteurization, such as 170 F for two min., and cool.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h3><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>EVALUATING MILK FLAVOR</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h3> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Understanding how we perceive flavors aids in flavor evaluation. Flavor is a blend of sensations from several sensory organs. The most important sensations contributing to milk's flavor are the taste, smell and feel.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Taste is detected in the mouth, principally on the tongue. There are only four tastes—sweet, sour, salt and bitter. To produce a taste sensation, a substance must be in solution in order to diffuse into the receptor sites in the taste buds.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Odor is detected by olfactory nerves in the nasal passages. The number of odors is almost limitless, and many are difficult to describe. To have an odor a substance must be volatile. Most compounds with strong odors are more soluble in fat than in water, whereas the reverse is true of most substances with pronounced tastes.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Another sensation that contributes to flavor is the way the food feels in the mouth. Some tactile characteristics of milk are smoothness, chalkiness, and richness attributable to consistency.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Although most milk is drunk cold, warming milk enhances its odor and facilitates detection of off-flavors. For quality control evaluations, milk usually warmed to about 70 F. The bottle should be shaken, the cap removed and the sample smelled. A head space above the milk (e.g. bottle two-thirds full) aids in evaluating odors.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Next, the sample should be tasted. The milk should be moved around in the mouth to contact all portions, particularly of the tongue, and to promote volatilization of compounds that contribute to the odor. Particular attention should be given to the changing sensations with time. Sweet, sour and salty tastes are usually detected quickly, whereas bitter tastes become evident more slowly but are retained longer.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>The most important step in learning to evaluate milk flavor is to gain proficiency in identifying defects. Correct identification provides helpful guidelines for control of defects. Evaluating the intensity of defects, however, is also of value in quality control programs.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Many different systems for designating intensity of flavors are in use. In some, intensity is indicated only by descriptive terms such as slight, distinct or strong, or by one, two or three plus signs. A simple numerical system applies scores for these descriptive terms: 0, no criticism; 1, slight; 2, distinct; and 3, strong. An inverse of this scale, or one giving a higher maximum score for flavor, such as 5 or 10 points, is preferable for quality scoring as it recognizes higher quality with a higher score. Any numerical system is arbitrary, but there is an advantage in selecting one that is in common use. In the United States a system that is widely used assigns scores within the range 10 for good milk to 0 for poor milk.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h3><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>TROUBLE-SHOOTING FLAVOR DEFECTS</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h3> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>If an off-flavor is found in a milk sample, a systematic approach helps in identifying the defect and its cause. An experienced individual will identify the most common off-flavors of milk by taste, and will be able to proceed immediately to determine the most probable cause. A beginner in flavor quality control work will be guided in his identification of off-flavors by comparing defective samples with samples having known off-flavors prepared as described above. Changes in intensity of a defect during storage provide helpful evidence regarding its identity. Hence, samples should be tasted fresh and again after storage in a refrigerator for at least 48 hr.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h3><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>RAW MILK</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h3> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>To pin-point possible causes of off-flavors in raw milk, it is helpful to collect milk samples at different steps. Samples might be collected from individual cows, at the discharge from the pipeline milker, from individual cans or the bulk tank, from the tank after only one milking and later at the time the milk is collected, or from morning and evening milkings separately.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>If an off-flavor is present in a fresh sample collected from pooled raw milk, it is usually attributable to feed. In some cases, there may be a marked difference between morning and evening milk in intensity of the off-flavor. Examining the feeds for known troublesome materials may substantiate suspicions regarding possible causes. Recommendations for corrective measures include:</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <div> <ul><li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Use only feeds that cause little or no feed flavor. Eliminate weeds from pastures and from crops to be used for hay or concentrates.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Arrange feeding schedule to</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Prevent the cows from eating feeds that may cause off-flavors during the 4-5 hr. before milking. Provide an environment where the cow can breathe fresh air free of feedy, cowy or barny odors.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> </ul></div> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Individual cows in a herd may produce milk with an off-flavor when it is drawn, such as a salty taste attributable to mastitis or advanced lactation, or a cowy flavor caused by ketosis. It is rare that such defects can be identified in the mixed milk from the entire herd, but they make the pooled supply less palatable. Therefore, milk from such cows should be withheld from the pooled milk.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>In some instances, the cow may appear to be responsible for off-flavors that are actually caused by equipment, or treatment of the cow or equipment. Examples are a medicinal flavor from salves used on the teats or udder, or chlorophenol flavor from plastic or rubber parts of the milking equipment.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>If an off-flavor is not present in fresh milk, but develops during storage, possible identities are light activated, oxidized, rancid and microbial flavors. Light-activated is the least likely in raw milk, and in any case its cause and correction would be immediately apparent. Comparison with reference samples aids in differentiating between oxidized and rancid flavors. Also, pasteurization of the fresh sample prevents development of rancid and bacterial flavors but not oxidized flavor. Some microbial flavors caused by psychrophilic bacteria are difficult to differentiate from rancid flavor because the bacteria produce lipolytic enzymes that release fatty acids, and also proteolytic enzymes that yield degradation products from protein with similar flavors. Information from bacterial counts of the milk, inspection of equipment, and checking on sanitizing procedures and cooling practices indicates whether bacterial flavors may be involved. If the defect appears to be rancid flavor, a chemical test for free fatty acids could be used for confirmation.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Rancidity that occurs in raw milk supplies usually is induced by an activating treatment: either excessive agitation of warm milk or temperature fluctuations between 50 and 86 F. Eliminating the activating condition usually prevents development of the defect. Determining the susceptibility of milk from individual cows is also helpful. Cows that produce the most susceptible milk are usually in advanced lactation, and there is little loss in production resulting from drying them off.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>In correcting problems with oxidized flavor. If samples taken from individual cows indicate that a high proportion of the cows in the herd are producing milk in which the defect develops without metal contamination, the most practical control would be through the herd ration.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h3><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>PASTEURIZED MILK</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h3> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>In 'trouble-shooting' causes of defects in processed milk, samples should be collected from the raw milk storage tanks and at every step in processing where feasible. A good practice is to compare 'first-off' samples with samples collected near the end of a processing run. If product from one processing line feeds several fillers, samples should be taken from each filler. As for raw milk, the samples should be tasted fresh and after storage, except that a storage period of at least a week is preferable for most pasteurized products.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Identification of the defect, using prepared reference samples for comparison if necessary, is the first step toward effective control. Corrective measures for the most common defects were indicated in the first two papers in this series, and are summarized briefly here.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Limited shelf-life resulting from bacterial growth is usually caused by post-pasteurization contamination. Phosphatase tests may be run on freshly pasteurized products to check on adequacy of pasteurization. The unclean, fruity, bitter and putrid flavors that develop in pasteurized milk are usually attributable to growth of psychrophilic bacteria that do not survive pasteurization. Hence, critical evaluation of cleaning and sanitizing procedures is necessary in order to detect sources of post-pasteurization contamination. Checks on temperature and time of storage, and rotation of stock should also be included.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Rancid flavor should not develop in a properly pasteurized product, but activating treatments at some stage of processing may induce its development before pasteurization. Possible causes include mixing pasteurized homogenized products with raw milk, warming cooled milk to about 85 F and recooling, and excessive agitation and foaming of raw milk. If the intensity of the flavor increases during storage, the possibility that the milk was improperly pasteurized or was contaminated by raw milk should be checked by use of the phosphatase test.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Problems with oxidized flavor may be caused primarily by low oxidative stability of the milk as produced, but are aggravated by abuse at any stage of processing and distribution. Particular attention should be given to avoiding copper contamination from white metal and other copper-containing alloys, and to minimizing exposure to light. Use of higher pasteurizing temperatures may be helpful if the more severe heat treatment does not produce objectionable heated flavors. Milk that is susceptible to oxidized flavor may be directed into homogenized products, as homogenization inhibits oxidized flavor. Locating causes of some atypical flavors in processed milk is sometimes a baffling assignment, even for people with extensive experience in flavor-control work. The approaches outlined above, however, provide guides to step-by-step elimination of possible causes of a defect.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h3><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>CONCLUSION</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h3> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>The objective of quality control personnel should be more than to prevent customer complaints. Routine daily examination of all processed products, fresh and after storage, usually results in recognition of off- flavors before they reach such intensity that they become objectionable to consumers. Much of the pasteurized milk sold today could be made more palatable by selecting milk of high quality initially, and giving increased attention to protecting its flavor during processing and distribution. Maintaining consumer confidence in the dependable high quality of milk is essential for maximum consumption.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <hr /><div><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Adapted by John C. Bruhn from articles written by:</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></div> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Professor Emeritus W. L. Dunkley and John C. Bruhn,<br /> University of California, <br /> Department Food Science and Technology, <br /> UC Davis, <br /> Davis, CA 95616-8598</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>March 1995</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> </div> <div class="field field--name-field-sf-article-category field--type-entity-reference field--label-above"> <div class="field__label">Category</div> <div class="field__item"><a href="/articles/dairy-processing/dairy-processing-information" hreflang="en">Dairy Processing Information</a></div> </div> Thu, 22 Jun 2017 22:58:00 +0000 Anonymous 406 at https://drinc.ucdavis.edu Federal and State Standards for Milk Products https://drinc.ucdavis.edu/dairy-processing/federal-and-state-standards-milk-products <span class="field field--name-title field--type-string field--label-hidden">Federal and State Standards for Milk Products</span> <span class="field field--name-uid field--type-entity-reference field--label-hidden"> <span lang="" typeof="schema:Person" property="schema:name" datatype=""> (not verified)</span> </span> <span class="field field--name-created field--type-created field--label-hidden">June 22, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-processing.rss" addthis:title="Dairy Processing" addthis:description=" Grade A Raw Milk  Temperature Cooled to 7 C(45 F) or less within two hours after milking, provided that the blend temperature after the first and subsequent milkings does not exceed 10 C(50 F). Bacterial Limits Individual producer milk not to exceed 100,000 per mL ( 50,000) prior to commingling with other producer milk. Commingled Not to exceed 300,000 (50,000) per mL as commingled milk prior to pasteurization. Coliform/Thermoduric Not to exceed 750/mL (California). Antibiotics No zone greater than or equal to 16mm with Bacillus sterothermoph-ilus disc assay method specified in Appendix G. No positive results on drug residue detection methods as referenced in Section 6. Laboratory Techniques. Somatic Cell Count Individual producer milk not to exceed 750,000/mL; individual goat milk to remain at 1,000,000/mL "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: " Grade A Raw Milk  Temperature Cooled to 7 C(45 F) or less within two hours after milking, provided that the blend temperature after the first and subsequent milkings does not exceed 10 C(50 F)." } } </script> <a class="addthis_button_twitter"></a> <a class="addthis_button_email"></a> <a class="addthis_button_compact"></a> </div> <div class="clearfix text-formatted field field--name-body field--type-text-with-summary field--label-hidden field__item"><div> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><strong>Grade A Raw Milk</strong> <br /> Temperature Cooled to 7 C(45 F) or less within two hours after milking, provided that the blend temperature after the first and subsequent milkings does not exceed 10 C(50 F).</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> </div> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><strong>Bacterial Limits</strong><br /> Individual producer milk not to exceed 100,000 per mL ( 50,000) prior to commingling with other producer milk.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><strong>Commingled</strong><br /> Not to exceed 300,000 (50,000) per mL as commingled milk prior to pasteurization.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><strong>Coliform/Thermoduric</strong><br /> Not to exceed 750/mL (California).</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><strong>Antibiotics</strong><br /> No zone greater than or equal to 16mm with Bacillus sterothermoph-ilus disc assay method specified in Appendix G. No positive results on drug residue detection methods as referenced in Section 6. Laboratory Techniques.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><strong>Somatic Cell Count</strong><br /> Individual producer milk not to exceed 750,000/mL; individual goat milk to remain at 1,000,000/mL</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> </div> <div class="field field--name-field-sf-article-category field--type-entity-reference field--label-above"> <div class="field__label">Category</div> <div class="field__item"><a href="/articles/dairy-processing/dairy-processing-information" hreflang="en">Dairy Processing Information</a></div> </div> Thu, 22 Jun 2017 22:57:05 +0000 Anonymous 401 at https://drinc.ucdavis.edu Cleaning and Sanitizing of Containers and Equipment https://drinc.ucdavis.edu/dairy-processing/cleaning-and-sanitizing-containers-and-equipment <span class="field field--name-title field--type-string field--label-hidden">Cleaning and Sanitizing of Containers and Equipment</span> <span class="field field--name-uid field--type-entity-reference field--label-hidden"> <span lang="" typeof="schema:Person" property="schema:name" datatype=""> (not verified)</span> </span> <span class="field field--name-created field--type-created field--label-hidden">June 22, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-processing.rss" addthis:title="Dairy Processing" addthis:description="&quot;The product contact surfaces of all multi-use containers, utensils, and equipment used in the transportation, processing, handling, and storage of milk or milk products shall be effectively cleaned and shall be sanitized before each use. Provided, that piping, equipment and containers used to process, conduct or package aseptically processed milk and milk products beyond the final heat treatment process shall be sterilized before any aseptically processed milk or milk product is packaged and shall be re-sterilized whenever any unsterile product has contaminated it.&quot; CLEANING OPERATIONS This item requires that all milk contact surfaces be effectively cleaned and sanitized before each use. The only exception to this is the Ordinance provision that milk storage tanks be emptied and cleaned at least every 72 hours and raw milk and heat treated milk storage tanks use to store products longer than 24 hours and all raw milk silo tanks be equipped with a 7-day temperature recording device. This recorder shall have a scale span of not less than 50 F, be accurate to plus or minus 2 F, include the normal storage temperatures plus and minus 5 F, with 2 F minimum scale divisions not less than 0.040 inch apart and time scale divisions of not more than 1 hour. The recording chart of these devices must be capable of recording temperatures up to 180 F. Computer generated temperature recorders which provide a printout which is readily discernible and meets the intent of the Ordinance are acceptable as are devices equipped with multiple sensors or recording pens. Records are a significant part of the cleaning and sanitizing process. All CIP charts are to be retained by the plant for a minimum of three (3) months. This includes records for cleaning and sanitizing of all plant product processing equipment. It is also recommended that log records are maintained of manual cleaning operations. This will enable plant quality control staff and the regulatory agency to validate plant cleaning/sanitizing operations. The Ordinance requires that the regulatory agency review and initial CIP charts during each inspection. Milk tank trucks shall be tagged or log book records maintained to verify each time the tanker is cleaned and sanitized. The wash tags shall only be removed at the plant or receiving station where the tanker is next cleaned and sanitized. These records shall be retained for 15 days for regulatory review. Note: Cultured product storage/processing vessels may not have to meet the 24 hour emptying and cleaning requirements if their process demands extended periods of storage, however, a plant should package cultured product within 24 hours of breaking the curd. Note: Cultured product storage/processing vessels may not have to meet the 24 hour emptying and cleaning requirements if their process demands extended periods of storage, however, a plant should package cultured product within 24 hours of breaking the curd. Recent changes in the PMO permit the restricted use of condensing water from milk evaporators and water reclaimed from milk or milk products as follows: Pre-rinsing of the product surfaces where pre-rinses will not be used in food products, and Cleaning solution make-up water; provided that for EITHER USE, ITEMS #3-11 OF APPENDIX D, V OF THE PMO 1 ARE MET..AND.. There is no carry-over water from one day to the next OR, The temperature of all water in the storage and distribution system is maintained at 63o C (145o F) or higher by automatic means, or The water is treated with a suitable, approved chemical to suppress bacterial growth by automatic methods prior to entering the storage tank, AND Distribution lines and hose stations are clearly identified as &quot;limited use reclaimed water&quot;, AND Water handling practices and guidelines are clearly described and prominently displayed at appropriate locations within the plant, AND These water lines are not permanently connected to product vessels, without a break to the atmosphere and sufficient automatic controls, to prevent the inadvertent addition of this water to product streams. NOTE: Recovered water may be used as boiler feedwater for boilers not used for generating culinary steam or in a thick, double walled, enclosed heat exchanger. Appendix D, V requires in Items 3 - 11, among other things a turbidity meter, chemical OD test, monitoring devices too automatically divert, organoleptic quality including weekly samples and records, allows addition of approved bacterial suppressants, and adequately constructed and protected storage vessels. CLEAN-IN-PLACE (CIP) The recommended steps in a clean in place (CIP) operation may involve the following: Remove those items that require manual cleaning such as fill tubes, manhole gaskets, plug valves, etc. Provide physical breaks between any circuits or tanks containing product. Pre-rinse or flush thoroughly with cool water not to exceed 80oF. Discard pre-rinse water, flushing until relatively clear. Circulate an effective detergent solution throughout the circuit for the period of time necessary to remove the residues in the circuit. Circulate a rinsing water. Circulate an acid detergent when needed followed by another rinse. Sanitize immediately before use. Most modern plants have installed clean-in-place systems throughout the plant. Prior to this, plants cleaned all their processing equipment, including tanks, vats, pumps and lines manually which involved complete disassembly, manually brushing with a cleaning solution, rinsing, reassembly and finally sanitizing. This was of course all highly labor intensive. In the early 1950&#039;s, companies such as Tri-Clover, Cherry-Burrell, and Alloy Products Corporation developed special CIP joint/gasket assemblies which were conducive to CIP methods. In the mid 1960&#039;s, clean in place systems led to the use of all-welded product piping systems, automatic (air operated) valving systems, large milk storage tanks or silos designed to be cleaned mechanically, and the installation of properly supported and self draining product lines (recommended minimum of 1/16 inch per foot slope). The process of circulation cleaning, which was first applied in the dairy industry in the 1940&#039;s, involves the continuous pumping of rinse (and often times pre-rinse) and wash solutions throughout the milk product circuits for the purpose of the removal of milk and milk residues rendering the inner surface clean to sight and smell. Now however, there may be separate CIP circuits for different processes, product lines, or product integrities. (raw vs.. pasteurized) and many plants have installed modern computer controls to monitor their cleaning processes. The CIP cycle begins at the &quot;make-up&quot; tank containing either a clean water rinse or dairy detergent wash solution. Both chlorinated alkaline and &quot;hot acid&quot; cleaners or caustics are used in the cleaning solution. The solution is circulated by using relatively higher velocity pumps capable of circulating the solution throughout the circuit, then returning it to the cleaning reservoir. Systems are monitored for temperature which is required under the Ordinance. Many modern systems also are monitoring , controlling and recording the levels of, pH concentration of cleaning detergent and sometimes flow rates. Temperatures shall be measured and recorded in the return solution line near the make up tank, however other means of measuring, monitoring, and recording CIP solutions may be used if reviewed by the FDA and found acceptable by the local regulatory agency. Product storage tanks (except silo tanks) cleaned using circulation from the tank outlet through a pump which returns the solution to the tank spray ball would not have to be equipped with a recorder, providing there are no product lines or other attached CIP circuits involved. Special attention must be given to the adequate venting of large milk storage tanks including milk silo tanks. One process engineer has stated that the provision of two, unobstructed three inch openings will adequately vent any tank (horizontal or vertical) using temperatures of "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "&quot;The product contact surfaces of all multi-use containers, utensils, and equipment used in the transportation, processing, handling, and storage of milk or milk products shall be effectively cleaned and shall be sanitized before each use." } } </script> <a class="addthis_button_twitter"></a> <a class="addthis_button_email"></a> <a class="addthis_button_compact"></a> </div> <div class="clearfix text-formatted field field--name-body field--type-text-with-summary field--label-hidden field__item"><p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>"The product contact surfaces of all multi-use containers, utensils, and equipment used in the transportation, processing, handling, and storage of milk or milk products shall be effectively cleaned and shall be sanitized before each use. Provided, that piping, equipment and containers used to process, conduct or package aseptically processed milk and milk products beyond the final heat treatment process shall be sterilized before any aseptically processed milk or milk product is packaged and shall be re-sterilized whenever any unsterile product has contaminated it."</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h4><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>CLEANING OPERATIONS</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h4> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>This item requires that all milk contact surfaces be effectively cleaned and sanitized before each use. The only exception to this is the Ordinance provision that milk storage tanks be emptied and cleaned at least every 72 hours and raw milk and heat treated milk storage tanks use to store products longer than 24 hours and all raw milk silo tanks be equipped with a 7-day temperature recording device.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>This recorder shall have a scale span of not less than 50 F, be accurate to plus or minus 2 F, include the normal storage temperatures plus and minus 5 F, with 2 F minimum scale divisions not less than 0.040 inch apart and time scale divisions of not more than 1 hour. The recording chart of these devices must be capable of recording temperatures up to 180 F.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Computer generated temperature recorders which provide a printout which is readily discernible and meets the intent of the Ordinance are acceptable as are devices equipped with multiple sensors or recording pens.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Records are a significant part of the cleaning and sanitizing process. All CIP charts are to be retained by the plant for a minimum of three (3) months. This includes records for cleaning and sanitizing of all plant product processing equipment.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>It is also recommended that log records are maintained of manual cleaning operations. This will enable plant quality control staff and the regulatory agency to validate plant cleaning/sanitizing operations.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>The Ordinance requires that the regulatory agency review and initial CIP charts during each inspection.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Milk tank trucks shall be tagged or log book records maintained to verify each time the tanker is cleaned and sanitized. The wash tags shall only be removed at the plant or receiving station where the tanker is next cleaned and sanitized. These records shall be retained for 15 days for regulatory review.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Note: Cultured product storage/processing vessels may not have to meet the 24 hour emptying and cleaning requirements if their process demands extended periods of storage, however, a plant should package cultured product within 24 hours of breaking the curd.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Note: Cultured product storage/processing vessels may not have to meet the 24 hour emptying and cleaning requirements if their process demands extended periods of storage, however, a plant should package cultured product within 24 hours of breaking the curd.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Recent changes in the PMO permit the restricted use of condensing water from milk evaporators and water reclaimed from milk or milk products as follows:</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <div> <ol><li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Pre-rinsing of the product surfaces where pre-rinses will not be used in food products, and</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Cleaning solution make-up water; provided that for EITHER USE, ITEMS #3-11 OF APPENDIX D, V OF THE PMO 1 ARE MET..AND..</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span> <ul><li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>There is no carry-over water from one day to the next OR,</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>The temperature of all water in the storage and distribution system is maintained at 63o C (145o F) or higher by automatic means, or</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>The water is treated with a suitable, approved chemical to suppress bacterial growth by automatic methods prior to entering the storage tank, AND</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Distribution lines and hose stations are clearly identified as "limited use reclaimed water", AND</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Water handling practices and guidelines are clearly described and prominently displayed at appropriate locations within the plant, AND</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>These water lines are not permanently connected to product vessels, without a break to the atmosphere and sufficient automatic controls, to prevent the inadvertent addition of this water to product streams. NOTE: Recovered water may be used as boiler feedwater for boilers not used for generating culinary steam or in a thick, double walled, enclosed heat exchanger.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> </ul></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Appendix D, V requires in Items 3 - 11, among other things a turbidity meter, chemical OD test, monitoring devices too automatically divert, organoleptic quality including weekly samples and records, allows addition of approved bacterial suppressants, and adequately constructed and protected storage vessels.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> </ol></div> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><strong>CLEAN-IN-PLACE (CIP)</strong> The recommended steps in a clean in place (CIP) operation may involve the following:</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <div> <ol><li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Remove those items that require manual cleaning such as fill tubes, manhole gaskets, plug valves, etc.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Provide physical breaks between any circuits or tanks containing product.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Pre-rinse or flush thoroughly with cool water not to exceed 80oF.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Discard pre-rinse water, flushing until relatively clear.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Circulate an effective detergent solution throughout the circuit for the period of time necessary to remove the residues in the circuit.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Circulate a rinsing water.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Circulate an acid detergent when needed followed by another rinse.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Sanitize immediately before use.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> </ol></div> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Most modern plants have installed clean-in-place systems throughout the plant. Prior to this, plants cleaned all their processing equipment, including tanks, vats, pumps and lines manually which involved complete disassembly, manually brushing with a cleaning solution, rinsing, reassembly and finally sanitizing. This was of course all highly labor intensive.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>In the early 1950's, companies such as Tri-Clover, Cherry-Burrell, and Alloy Products Corporation developed special CIP joint/gasket assemblies which were conducive to CIP methods.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>In the mid 1960's, clean in place systems led to the use of all-welded product piping systems, automatic (air operated) valving systems, large milk storage tanks or silos designed to be cleaned mechanically, and the installation of properly supported and self draining product lines (recommended minimum of 1/16 inch per foot slope).</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>The process of circulation cleaning, which was first applied in the dairy industry in the 1940's, involves the continuous pumping of rinse (and often times pre-rinse) and wash solutions throughout the milk product circuits for the purpose of the removal of milk and milk residues rendering the inner surface clean to sight and smell.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Now however, there may be separate CIP circuits for different processes, product lines, or product integrities. (raw vs.. pasteurized) and many plants have installed modern computer controls to monitor their cleaning processes.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>The CIP cycle begins at the "make-up" tank containing either a clean water rinse or dairy detergent wash solution. Both chlorinated alkaline and "hot acid" cleaners or caustics are used in the cleaning solution.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>The solution is circulated by using relatively higher velocity pumps capable of circulating the solution throughout the circuit, then returning it to the cleaning reservoir.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Systems are monitored for temperature which is required under the Ordinance. Many modern systems also are monitoring , controlling and recording the levels of, pH concentration of cleaning detergent and sometimes flow rates.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Temperatures shall be measured and recorded in the return solution line near the make up tank, however other means of measuring, monitoring, and recording CIP solutions may be used if reviewed by the FDA and found acceptable by the local regulatory agency.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Product storage tanks (except silo tanks) cleaned using circulation from the tank outlet through a pump which returns the solution to the tank spray ball would not have to be equipped with a recorder, providing there are no product lines or other attached CIP circuits involved.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Special attention must be given to the adequate venting of large milk storage tanks including milk silo tanks.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>One process engineer has stated that the provision of two, unobstructed three inch openings will adequately vent any tank (horizontal or vertical) using temperatures of &lt;150o F. This is not a hard and fast rule but can be used as a guideline in considering adequate venting of CIP operations for tanks.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Before beginning a CIP of larger tanks and silos, the proper CIP venting door device should be installed in the manhole opening to provide adequate space for air movement resulting from extreme differentials in temperatures.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>The basic components of any CIP system will include the following:</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <div> <ol><li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Permanently installed product piping and air operated valves</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>CIP solution make-up tanks</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>CIP pumps</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>CIP supply and return solution piping</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Spray devices(either permanently mounted or drop- type)</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Solution collection manifolds</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Chemical feed systems and equipment</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>The CIP control/monitoring systems and necessary recorders. CIP temperature recorders must meet all requirements as listed in Appendix H, page 207 of the Ordinance.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> </ol></div> <h4><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>WATER CHARACTERISTICS AND AFFECTS ON MILK PLANT CLEANING OPERATIONS</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h4> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Water hardness is the term applied to water supplies characterized by either a high mineral content, usually high in calcium or magnesium bicarbonates, or magnesium chlorides, and sulfates. Generally water hardness is precipitated by most alkaline materials but not by heat.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Some plants may need to condition their water by either selecting the proper detergents or in more severe hard water cases may need to install ion exchangers to remedy the problem.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Water over 100ppm hardness apply in the latter cases and usually softeners are required for boiler water or cooling tower feed water supplies.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>The 3-A Accepted Practices for Permanently Installed Sanitary Product Pipelines and Cleaning Systems require that "All connections between the solutions circuit and the product circuit shall be constructed as to positively prevent the commingling of the product and solution during processing".</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Cleaning efficiencies may be enhanced by introducing pressurized air into the system and most systems are fitted with a method to eliminate entrapped air.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Some systems are designed to recover sanitizing solutions for use as a system pre-rinse on the following CIP cycle.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Vertical or silo tanks are cleaned not by sprays but rely on introduction of the cleaning solution at the top of the tank onto a diversion disc or plate which deflects the solution to make contact with the interior tank surfaces.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Also, the tank must be so fabricated and installed to be self draining and to have a fast flushing action across the bottom of the tank.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>No matter how sophisticated the CIP system may be, there will always be a need to clean those portions of the equipment not exposed to the cleaning process. Examples of this would be the agitator paddles in silo tanks, air blow fittings, plug type valves, tank venting devices, etc.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h5><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Clean Out of Place (COP)</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h5> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>This is the term used for those cleaning operations involving the removal of small sections of piping, valve parts, filler parts, and other small appurtenances that are not normally cleaned in place and placing them into a cleaning vat. The vat is equipped with a heat source, adequate dairy cleaner or caustic, normally steam injection, and a recirculating pump. Recording devices are not required on these units, although many plants have installed them to provide cleaning records as a part of their overall quality program.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h5><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Manual Cleaning Operations</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h5> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Regardless of the automation and engineering built into a plants operation, there is usually a need to manually clean the contact surfaces of the many small parts used in a normal days operation.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>This may include filler parts, valves, filler surfaces (mandrels, shields, guides, etc.), small vats, cultured product packaging equipment appurtenances, tanker pumps, fittings, and valves, culture room product handling utensils and equipment (processing vats, curd cutting knives, whey drainers, steam cookers, curd movers and stirrers, etc.).</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Manually washed fillers require hand brush washing of the filler bowl, gaskets, the product supply line, ells, and bushings.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Since brushes are used in manual washing operations, they must be of the non-absorbent, nylon or plastic bristled type and designed to not retain soil (not recommended to use hollow body or handled type) and be quick to dry. Brush integrity must be maintained so that brushes used for floor drains or similar surfaces are not used on contact surfaces. This may be accomplished by color coding, marking, etc.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Utensils should be cleaned using a two compartment wash and rinse sink. Sanitizing with chemicals must be accomplished using a third treatment vat, unless heat is used for sanitizing.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>The use of absorbent items, such as rags and sponges should be eliminated to reduce the potential of spreading microorganisms throughout the plant environment.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Separate brushes should be used for product and not-product surfaces and the use of wooden handled brushes, tools, paddles, etc. should not be used in production areas.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Particular attention must be given to cleaning underneath gaskets, "o-rings", and other small orifices in which residue and bacteria may accumulate.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Special emphasis should be given to the following when evaluating the effective cleaning of milk contact surfaces:</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <div> <ul><li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>AUP air blow devices/fittings;</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Storage tank agitator blades, shafts, fill inlets, vents, gaskets, shaft "O" rings;</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Filler valves, tanks, small parts (springs, screens, gaskets and "O" rings, vents, drain valve and lines, underside of shielding,);</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Plug valves, "butterfly valves";</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Fruit feed pumps, (varigators), fruit pumps;</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Homogenizer stand pipes;</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Reclaimed product surge tanks, milk cans, lines;</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Silo manhole doors (inside surfaces, sampling cocks, tank surface on inside below door opening);</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Silo vent caps (mold, slime);</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Liquefier (powder mixing tanks) outlet valve and connecting piping;</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Raw receiving lines and fittings;</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Product pumps ("O" rings, back plates, covers);</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Filter housings, springs, gaskets in raw receiving area;</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Air eliminators in receiving areas, air "burps" on product and CIP lines;</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Pasteurizer regenerator plates (points of greatest temperature differential);</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>vacuum breakers, single stem flow diversion valves;</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Tank fill goose necks; and In-door sample valves.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> </ul></div> <h4><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>CHEMICALS USED IN MILK PLANT CLEANING OPERATIONS</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h4> <h5><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>ALKALINE DETERGENTS </span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h5> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Used to neutralize, break-up, and suspend soil in the cleaning solution. Alkalines have been termed the "guts" of the dairy cleaners and are usually termed generically as "caustics" and or alkaline chlorinated cleaners.. Chemically they are sodium hydroxide (NaOH, OR CAUSTIC SODA), potassium hydroxide (caustic potash), sodium carbonate (soda ash) or sodium hypochloride (NaOCL) and sodium silicates and have a pH higher than 7. They attack the fat and protein residues on all types of dairy processing equipment.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>They are generally combined with a water conditioning additive such as liquid phosphate under hard water conditions and usually contain surfactants or wetting agents which enhances the cleaning action.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>The water properties must be considered, since most cleaning solutions are made up of 99% water and the amount of neutralizers used should be customized to meet the individual demands. These detergents condition the water to prevent scum formation, and help to prevent saponification (the chemical reaction which converts the actions of alkali and fats into soap and glycerin) during the cleaning cycle.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Most alkaline detergents contain chlorine which also breaks down the fats and proteins.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h5><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>ACID CLEANERS </span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h5> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Acid detergents are those with a pH of lower than 7 and react with mineral deposits which have accumulated on milk contact surfaces. These acid cleaners may contain either nitric, phosphoric or a mixture of both acids; however phosphoric acid based cleaners are the most widely used in the U.S.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Milk and water mineral deposits (termed milk stone) become hardened and layered on the equipment surfaces and provide excellent surfaces on which "biofilms", which are adherent macro-colonies of bacteria, may thrive. Milk stone may consist of milk solids, calcium, magnesium, iron, sulfates, etc.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Acid based detergents (or rinses) do not saponify. They do, however, tend to neutralize any alkalinity and react with the milk minerals which are then carried away in the rinse cycles. Acid rinses will usually provide a bacteriostatic condition, however the equipment must be effectively cleaned with an chlorinated alkaline based detergent prior to using the acid rinse.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Using an acid detergent without first removing the fats and proteins with a chlorinated alkaline detergent will result in fixing the protein soil to the surface. Acid rinses may also tend to protect against corrosion and when used in proper strengths will not attack rubber parts.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <div><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>MILKSTONE White to yellow Minerals from milk Acid wash Regular and proper cleaning procedures coupled w/ acidified rinse FAT/ GREASE Hanging water droplets Greasy (white) appearance 1. Low water temperatures 2. Improper detergent concentration 3. Regular use of acids in place of alkaline detergent 1. Proper water temperature 2. Correct concentration of alkaline detergent Regular and proper cleaning procedures coupled w/ acidified rinse MINERAL (Calcium, Magnesium) White (water- stone) chalky to gray 1. Rinse too hot, drop-out of minerals from water supply 2. Failure to use acid detergents 3. No acidified rinse 4. Alkaline detergent used cannot handle hard water at present concentration Acid wash 1. Acid wash 2. Alkaline detergent used has good water conditioning 3. Water softener or treatment</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span> <table><tbody><tr><td> <div><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><strong>RESIDUE IDENTIFICATION CHART</strong></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></div> </td> </tr><tr><td><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Residue</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></td> <td><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Description / Appearance</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></td> <td><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Cause</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></td> <td><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Removal</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></td> <td><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Prevention</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></td> </tr><tr><td><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>PROTEIN</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></td> <td><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Blue rainbow hue varnish like, "apple sauce"</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></td> <td><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>1. Using non-chlorinated cleaner<br /> 2. Inadequate pre-rinse<br /> 3. Improper cleaning</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></td> <td><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Chlorinated alkaline detergent</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></td> <td><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>1. Adequate pre-rinse<br /> 2. Proper cleaning w/ proper use dilution after each usage<br /> 3. Chlorinated alkaline detergent</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></td> </tr></tbody></table></div> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><strong>NOTE: NEVER MIX CHLORINE AND ACID BASED DETERGENTS TOGETHER</strong></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>The following is a list of terms commonly used when referring to the properties of detergents used in the food industry.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <div> <ol><li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Emulsification - The spontaneous dispersion of substances (proteins, gross soil particles, etc.) when brought in contact with water.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Peptize - The mechanical action combined with a surfactant which results in two immiscible liquids to form a stabilized colloid.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Saponification - The combination of fatty acids and oils with alkali to produce soap.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Sequestering and Chelating - The prevention of precipitation of hard water constituents by keeping them in suspension as stable and solid compounds.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Wetting - Lowering of surface tension which permits cleaners to break the bond between the soil and surfaces.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> </ol></div> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>The Ordinance requires that cleaned milk contact surfaces of equipment be sanitized before each use and that aseptic processing equipment shall be sterilized before use and re-sanitized or re-sterilized in all instances whenever contaminated.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>IT MUST BE STRESSED THAT CHEMICAL SANITIZERS ARE NOT EFFECTIVE UNLESS ALL PRODUCT SURFACES ARE EFFECTIVELY CLEANED PRIOR TO THEIR APPLICATION.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>For our purposes only conventional milk processing sanitizing will be addressed in this section.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>All multi-use containers, equipment, and utensils must be sanitized before use. The method of sanitization may be either by chemicals or the heat method.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Adequate sanitization may be accomplished by using one of the methods as described in the following table.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Chemical Sanitizers: General Information</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>GENERAL INFORMATION - The Code of Federal Regulations (CFR's), Title 21, Part 178, Section 1010, Page 316-323, lists all the acceptable sanitizers available for use in food plants. This section list the chemistry and general guidelines for use for each sanitizer, including the recommended strengths. Federal codes also prohibit the use of any chemical in a strength higher than that recommended to accomplish its intended purpose in an effort to reduce the possibilities of harmful chemical residues in food products.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h5><strong><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>1. CHLORINE</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></strong></h5> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Chlorine is the most common chemical sanitizing agent used in the milk industry. One of the more common forms of chlorine is sodium hypochlorite which is the soluble salt of hypochlorous acid combined with sodium chloride. This is the stable form of a liquid chlorine solution however has a limited shelf life.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Granular chlorine sanitizers are based upon the salts of an organic carrier which contains releasable chlorine ions. When blended with water, sodium hypochlorite is released and the hypochlorous acid is the active antimicrobial for all chlorine sanitizers.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>The killing rate of chlorine is greatly influenced by the pH of the solution. For instance at a solution of 25 ppm chlorine will deactivate organisms at pH 4 in 15 seconds, while a pH level of 10 would take up to 10 minutes. Temperatures of the solution also play an important role in chlorine effectiveness rates. Optimum temperatures of chlorine range from 75o F - 100o F.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Chlorine solutions deactivate the microorganisms by affecting the cell wall transport mechanisms, causing the formation of chloramines with the amino acids of proteins. This denatures the proteins within the enzymes causing intracellular damage and destroys the microbe.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Chlorine sanitizers are generally used in recirculated cleaning systems for cleaning small parts, milk tank trucks and environmental surfaces.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h5><strong><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>2. IODINE</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></strong></h5> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Iodine sanitizers used in milk plants are usually in the form of iodophors. Iodophors are simply iodine which are combined with non-ionic wetting agents (surfactants). Iodophors, when diluted for use in the proper concentrations, have a low pH value (pH 2.6 - 5.0) which enhances their germicidal qualities. This along with increased temperatures (up to 120o F) makes them a popular sanitizer for use in milk plants.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Iodine interferes with the intracellular protein in a similar manner to that of chlorine, with the sulfhydryl, amino or carbonyl protein groups being affected.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Iodine sanitizers are used extensively in filling/packaging machines and areas, culture processing equipment, drop hoses and hand dipping stations.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h5><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>3. QUATERNARY AMMONIUM COMPOUNDS (Cationics)</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h5> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>These sanitizer agents are commonly known as "Quats" and are highly effective in the denaturing of cell (bacteria) proteins which leads to their destruction.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Bacterial cells walls are electrically charged and can possess a net positive or negative charge largely depending on the acidity of the solution in which they are found. Moreover, each type of bacteria have a different cell wall composition. Generally bacteria grow in the optimum pH range of 6.0 to 8.0, and are generally negatively charged at this growth range. The cationic sanitizer, having a positive charge, attracting their opposite charge (negative). This interaction between the opposite charges tends to produce drastic effects upon the cell wall and will cause fluid leakage and eventually cellular rupture. In concentrations of 50 -100 ppm cationic surfactants will not only denature the cells proteins, but also totally inactivate the enzyme and actually alter the cell wall permeability.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Quats are generally used in case washing areas and other environmental surfaces, but are rarely used in CIP and plant equipment sanitization where culture processes may be damaged.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h5><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>4. <strong>CHLORINE DIOXIDE</strong></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h5> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>This chemical sanitizer has become more widely used in the dairy industry, predominately in the sanitizing of environmental surfaces of equipment, floor drains, and other areas to greatly reduce the microbial load in these area. Recommended (CFR) effective uses of this sanitizer for contact surfaces must not exceed 200ppm and a recommended strength of 100-200ppm has been established. The CFR describes the formulation for this sanitizer by either metering a concentrated chlorine dioxide solution into potable water or by acidification of an aqueous alkaline solution of the oxychloro species.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h5><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>5. ACID SANITIZERS</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h5> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Aqueous solutions containing one or several of the acceptable acid sanitizers has been effective in the deactivation of microbes. The active acid ingredient may be sulfonic, phosphoric, de-cationic, cyanuric or a blend of the above to provide not more than 100ppm of available halogen.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Note: Trichoromelamine based sanitizers are not approved for use on milk contact surfaces.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Acid sanitizers are used primarily for large (silo) milk storage tanks, milk tankers and other large milk storage vessels within the plant.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h4><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>STORAGE OF CLEANED CONTAINERS AND EQUIPMENT</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h4> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>"After cleaning, all multi-use milk or milk product containers, utensils, and equipment shall be transported and stored to assure complete drainage, and shall be protected from contamination before use".</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Once the milk processing equipment has been properly cleaned special care must be taken to prevent contamination prior to the next use. Cleaned equipment and/or utensils must be stored to be protected from splash, dust, insects, overhead dripping, condensation, unnecessary handling, or any other possible source of contamination.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Multi-use utensils, containers and equipment must be stored above the floor on clean racks or other storage devices, inverted for protection and drainage. Care must be taken not to contaminate the clean equipment or utensils by splash from floor, wall or ceiling cleaning operations.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Portable packaging machines must be stored in areas where contamination is less likely, preferable in processing equivalent rooms or acceptable dry storage rooms and should be protected in some manner such as covering with clean plastic sheeting, etc.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Clean equipment must never be stored on dock areas, in machinery areas (boiler or sweet water rooms), or in out-buildings which are not vermin proof or otherwise unsuitable for food processing equipment storage.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h4><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>PROS AND CONS OF CHEMICAL SANITIZERS</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h4> <h5><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>CHLORINE ADVANTAGES</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h5> <div> <ol><li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Economical</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Effective against most bacteria, spores, phages</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Readily available in liquid or granular form</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Not affected by hard water salts</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Test kits available</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> </ol><h5><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>CHLORINE DISADVANTAGES</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h5> <ol><li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Corrosive</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Effectiveness is pH dependent</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Strength dissipates under storage, heat or light</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Skin irritant, objectionable odor</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Hard on rubber parts</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> </ol></div> <h5><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>IODINE ADVANTAGES</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h5> <div> <ol><li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Color indicative of strength</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Activity less affected by organics</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Effective against wide variety of non-sporeformers</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Solution not affected by hard water salts</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Not a skin irritant</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Stable, long shelf life</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Non-corrosive</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Test kit available</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> </ol><h5><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>IODINE DISADVANTAGES</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h5> <ol><li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Effectiveness decreases with increased pH</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>May discolor equipment</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Less effective against spores</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Should be used above 120o F.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>May cause product off flavors</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> </ol></div> <h5><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>QUATERNARY AMMONIUM COMPOUNDS (Cationics) ADVANTAGES</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h5> <div> <ol><li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Active against wide range of organisms, especially gram positive slime-formers, thermodurics</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Low toxicity, odorless, colorless</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Non-corrosive</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Stability excellent</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Heat stable, long lasting</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Less affected by pH</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Non-irritant to skin</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> </ol><h5><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>QUATERNARY AMMONIUM COMPOUNDS (Cationics) DISADVANTAGES</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h5> <ol><li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Undesirable in cultured dairy product applications</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Low activity against gram negative and coliform organisms</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Loses effectiveness with anionic detergent contamination.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> </ol></div> <h5><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>ANIONIC ACIDS ADVANTAGES</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h5> <div> <ol><li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Non-corrosive</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Unaffected by hard water, temperature, or organic contaminants</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Rapid activity</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Effective on wide range of microbes(thermodurics, phages, and yeasts)</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Controls milk-stone</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> </ol><h5><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>ANIONIC ACIDS DISADVANTAGES</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h5> <ol><li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Increase in pH level decreases effectiveness</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Cannot be used with alkaline detergents</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Is less effective against thermo- durics, spores, psychrophils</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Relatively expensive</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Leaves foam residual in CIP applications</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> </ol></div> </div> <div class="field field--name-field-sf-article-category field--type-entity-reference field--label-above"> <div class="field__label">Category</div> <div class="field__item"><a href="/articles/dairy-processing/dairy-processing-information" hreflang="en">Dairy Processing Information</a></div> </div> Thu, 22 Jun 2017 22:52:15 +0000 Anonymous 396 at https://drinc.ucdavis.edu Milk Quality Terms https://drinc.ucdavis.edu/dairy-processing/milk-quality-terms <span class="field field--name-title field--type-string field--label-hidden">Milk Quality Terms</span> <span class="field field--name-uid field--type-entity-reference field--label-hidden"> <span lang="" typeof="schema:Person" property="schema:name" datatype=""> (not verified)</span> </span> <span class="field field--name-created field--type-created field--label-hidden">June 22, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-processing.rss" addthis:title="Dairy Processing" addthis:description=" Bacterial Count The number of bacteria just viable or both viable and nonviable depending on method of analysis. As examples, plate counts determine numbers of viable bacteria capable of growth under conditions imposed, whereas direct microscopic counts enumerate all stainable cells both living and dead Bactericide An agent or substance capable of destroying bacteria. Bacteriostatic A substance that prevents the growth of bacteria but does not kill them. B.O.D.(Biochemical Oxygen Demand) The amount of oxygen required to maintain aerobic conditions during decomposition of factory wastes such as whey. The effect of excessive waste in streams is that it uses up dissolved oxygen, thereby creating objectionable conditions and making it impossible for aquatic life to survive. Casein The major protein of milk. CIP (cleaned in place) Most stainless steel pipelines are cleaned by circulating washing solutions through them. Coliform Bacteria The coliform group of bacteria comprises all aerobic and facultatively anaerobic, gram-negative nonspore forming rods capable of fermenting lactose with the production of acid and gas at 90°F (32°C) within 48 hours. While the general source of these organisms is commonly accepted to be the intestinal tract of warm-blooded animals, it is emphasized that bacteria of both fecal and non-fecal origin are members of this group. Typically, these organisms are classified in the genera Escherichia and Enterobacter (formerly Aerobacter); but, in addition, a few lactose-fermenting species of other genera are included in the group. In proportion to the numbers present, the existence of any of these types in dairy products is suggestive of unsanitary conditions or practices during production, processing or storage. Coliform Count The coliform bacteria count is used as an index of the level if sanitation and/or water quality employed in the handling and processing of milk products. Coliforms have significance in milk and milk products because (1) they are easily killed during pasteurization and because (2) they are generally regarded to originate from the intestinal tract of warm-blooded animals. Hence, the presence of coliform bacteria in pasteurized milk products is suggestive of unsanitary conditions or practices during processing, packaging; maximum standards for number of coliforms have until now been set at a maximum of 10 per milliliter of gram in pasteurized milk and milk products; however, numbers in pasteurized dairy products should be less than 1 ml., as is the case with up to 90% of samples, if packaging procedures are correct. California standard allows no more than 750 coliforms per mL in raw milk. Less than 100 is considered acceptable. Enzyme A complex organic substance that will accelerate (catalyze) specific chemical transformation. For example, lipase, fat splitting, and protease, protein splitting enzymes are always found in milk, and are sometimes involved in milk spoilage. Escherichia Coli (E. Coli) Certain serological groups of Escherichia coli are known to produce severe diarrhea in infants and young children. Both animals and man are carriers of Enteropathogenic E. coli, the organisms having been recovered from the milk of healthy animals as well as those with mastitis. Lab Pasteurized Count Bacteria that survive specific heat treatments (i.e., vat or high temperature short time (HTST) pasteurization) are usually said to be thermoduric (heat tolerant). A practical laboratory test involves heat treatment of representative raw bulk milk samples at 145°F (63°) for 30 minutes (equivalent of vat pasteurization minimum conditions). The Standard Plate Count method is used to enumerate the surviving microorganisms. In raw milk, less than 100/ml is desirable; more than 750/mL is illegal under California regulations. Pasteurization Temperature Time 145°F (63°C) (Batch) 30 minutes 161°F (72°C) (HTST) 15 minutes 191°F (89°C) (HHST) 1.0 second 194°F (90°C) (HHST) 0.5 second 201°F (94°C) (HHST) 0.1 second 204°F (96°C) (HHST) 0.05 second 212°F (100°C) (HHST) 0.01 second 280°F (138°C) (Ultra-pasteurized) 2.0 seconds P.I. Count Preliminary Incubation Count - this is a method of counting the bacteria in milk that grow at low temperatures and are not usually counted by the Standard Plate Count method. Incubation of the raw milk sample is at 55°F (13°C) for 18 hours (or other time/temperature combination) prior to plating. Good P.I. counts should be similar to raw milk SPS&#039;s, that is less than 20,000/ml. Not all dairy researchers believe this count &quot;adds&quot; to understanding troublesome counts in raw milk. PPM Parts pre million. It equals milligrams per kilogram or microliter per liter. Psychrotrophic Cold tolerant. It refers to microorganisms that grow at low temperatures, below 45°F (7°C), but have an optimum temperature of 59°F to 70°F (15°C to 21°C). These organisms especially affect the shelf life of refrigerated dairy products, such as cottage cheese. Quality A term used to indicate the desirability and/or acceptability of an animal or food product. Sanitize To kill or remove injurious microorganisms but not necessarily to sterilize. Dairy equipment is commonly sanitized with hot water or chemicals. Shelf Life The time after processing during which a product remains suitable for human consumption, especially the time a food remains palatable and acceptable to consumers. Standard Plate Count (SPC) The SPC has long been the primary test for determining the bacterial density (quality) of fresh raw or pasteurized grade A milk. The SPC estimates the total numbers of aerobic type microorganisms. In conducting this procedure, careful consideration must be given to nutrients of plating medium, the temperature and time of incubation, and proper dilution of the sample to avoiding overcrowding of colonies on plates. Samples must be representative, collected with contamination, and stored under conditions that will not allow bacterial growth or destruction (below 40° but above 32°F) (below 4 °C above 0°C), and tested within 36 hours of collection. Sterilize To remove or kill all living organisms. "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: " Bacterial Count The number of bacteria just viable or both viable and nonviable depending on method of analysis." } } </script> <a class="addthis_button_twitter"></a> <a class="addthis_button_email"></a> <a class="addthis_button_compact"></a> </div> <div class="clearfix text-formatted field field--name-body field--type-text-with-summary field--label-hidden field__item"><div> <dl><dd><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><strong>Bacterial Count</strong></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></dd> <dd><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>The number of bacteria just viable or both viable and nonviable depending on method of analysis. As examples, plate counts determine numbers of viable bacteria capable of growth under conditions imposed, whereas direct microscopic counts enumerate all stainable cells both living and dead</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></dd> </dl></div> <dl><dt> <div><strong>Bactericide</strong></div> </dt> <dd> <div>An agent or substance capable of destroying bacteria.</div> </dd> <dt> <div><strong>Bacteriostatic</strong></div> </dt> <dd> <div>A substance that prevents the growth of bacteria but does not kill them.</div> </dd> <dt> <div><strong>B.O.D.(Biochemical Oxygen Demand)</strong></div> </dt> <dd> <div>The amount of oxygen required to maintain aerobic conditions during decomposition of factory wastes such as whey. The effect of excessive waste in streams is that it uses up dissolved oxygen, thereby creating objectionable conditions and making it impossible for aquatic life to survive.</div> </dd> <dt> <div><strong>Casein</strong></div> </dt> <dd> <div>The major protein of milk.</div> </dd> <dt> <div><strong>CIP (cleaned in place)</strong></div> </dt> <dd> <div>Most stainless steel pipelines are cleaned by circulating washing solutions through them.</div> </dd> <dt> <div><strong>Coliform Bacteria</strong></div> </dt> <dd> <div>The coliform group of bacteria comprises all aerobic and facultatively anaerobic, gram-negative nonspore forming rods capable of fermenting lactose with the production of acid and gas at 90°F (32°C) within 48 hours. While the general source of these organisms is commonly accepted to be the intestinal tract of warm-blooded animals, it is emphasized that bacteria of both fecal and non-fecal origin are members of this group. Typically, these organisms are classified in the genera Escherichia and Enterobacter (formerly Aerobacter); but, in addition, a few lactose-fermenting species of other genera are included in the group. In proportion to the numbers present, the existence of any of these types in dairy products is suggestive of unsanitary conditions or practices during production, processing or storage.</div> </dd> <dt> <div><strong>Coliform Count</strong></div> </dt> <dd> <div>The coliform bacteria count is used as an index of the level if sanitation and/or water quality employed in the handling and processing of milk products. Coliforms have significance in milk and milk products because (1) they are easily killed during pasteurization and because (2) they are generally regarded to originate from the intestinal tract of warm-blooded animals. Hence, the presence of coliform bacteria in pasteurized milk products is suggestive of unsanitary conditions or practices during processing, packaging; maximum standards for number of coliforms have until now been set at a maximum of 10 per milliliter of gram in pasteurized milk and milk products; however, numbers in pasteurized dairy products should be less than 1 ml., as is the case with up to 90% of samples, if packaging procedures are correct. California standard allows no more than 750 coliforms per mL in raw milk. Less than 100 is considered acceptable.</div> </dd> <dt> <div><strong>Enzyme</strong></div> </dt> <dd> <div>A complex organic substance that will accelerate (catalyze) specific chemical transformation. For example, lipase, fat splitting, and protease, protein splitting enzymes are always found in milk, and are sometimes involved in milk spoilage.</div> </dd> <dt> <div><strong>Escherichia Coli (E. Coli)</strong></div> </dt> <dd> <div>Certain serological groups of Escherichia coli are known to produce severe diarrhea in infants and young children. Both animals and man are carriers of Enteropathogenic E. coli, the organisms having been recovered from the milk of healthy animals as well as those with mastitis.</div> </dd> <dt> <div><strong>Lab Pasteurized Count</strong></div> </dt> <dd> <div>Bacteria that survive specific heat treatments (i.e., vat or high temperature short time (HTST) pasteurization) are usually said to be thermoduric (heat tolerant). A practical laboratory test involves heat treatment of representative raw bulk milk samples at 145°F (63°) for 30 minutes (equivalent of vat pasteurization minimum conditions). The Standard Plate Count method is used to enumerate the surviving microorganisms. In raw milk, less than 100/ml is desirable; more than 750/mL is illegal under California regulations.</div> </dd> <dt> <div><strong>Pasteurization</strong></div> </dt> <dd> <div>Temperature Time 145°F (63°C) (Batch) 30 minutes 161°F (72°C) (HTST) 15 minutes 191°F (89°C) (HHST) 1.0 second 194°F (90°C) (HHST) 0.5 second 201°F (94°C) (HHST) 0.1 second 204°F (96°C) (HHST) 0.05 second 212°F (100°C) (HHST) 0.01 second 280°F (138°C) (Ultra-pasteurized) 2.0 seconds</div> </dd> <dt> <div><strong>P.I. Count</strong></div> </dt> <dd> <div>Preliminary Incubation Count - this is a method of counting the bacteria in milk that grow at low temperatures and are not usually counted by the Standard Plate Count method. Incubation of the raw milk sample is at 55°F (13°C) for 18 hours (or other time/temperature combination) prior to plating. Good P.I. counts should be similar to raw milk SPS's, that is less than 20,000/ml. Not all dairy researchers believe this count "adds" to understanding troublesome counts in raw milk.</div> </dd> <dt> <div><strong>PPM</strong></div> </dt> <dd> <div>Parts pre million. It equals milligrams per kilogram or microliter per liter.</div> </dd> <dt> <div><strong>Psychrotrophic</strong></div> </dt> <dd> <div>Cold tolerant. It refers to microorganisms that grow at low temperatures, below 45°F (7°C), but have an optimum temperature of 59°F to 70°F (15°C to 21°C). These organisms especially affect the shelf life of refrigerated dairy products, such as cottage cheese.</div> </dd> <dt> <div><strong>Quality</strong></div> </dt> <dd> <div>A term used to indicate the desirability and/or acceptability of an animal or food product.</div> </dd> <dt> <div><strong>Sanitize</strong></div> </dt> <dd> <div>To kill or remove injurious microorganisms but not necessarily to sterilize. Dairy equipment is commonly sanitized with hot water or chemicals.</div> </dd> <dt> <div><strong>Shelf Life</strong></div> </dt> <dd> <div>The time after processing during which a product remains suitable for human consumption, especially the time a food remains palatable and acceptable to consumers.</div> </dd> <dt> <div><strong>Standard Plate Count (SPC)</strong></div> </dt> <dd> <div>The SPC has long been the primary test for determining the bacterial density (quality) of fresh raw or pasteurized grade A milk. The SPC estimates the total numbers of aerobic type microorganisms. In conducting this procedure, careful consideration must be given to nutrients of plating medium, the temperature and time of incubation, and proper dilution of the sample to avoiding overcrowding of colonies on plates. Samples must be representative, collected with contamination, and stored under conditions that will not allow bacterial growth or destruction (below 40° but above 32°F) (below 4 °C above 0°C), and tested within 36 hours of collection.</div> </dd> <dt> <div><strong>Sterilize</strong></div> </dt> <dd> <div>To remove or kill all living organisms.</div> </dd> </dl> </div> <div class="field field--name-field-sf-article-category field--type-entity-reference field--label-above"> <div class="field__label">Category</div> <div class="field__item"><a href="/articles/dairy-processing/dairy-processing-information" hreflang="en">Dairy Processing Information</a></div> </div> Thu, 22 Jun 2017 22:50:46 +0000 Anonymous 391 at https://drinc.ucdavis.edu The 3-A Program https://drinc.ucdavis.edu/dairy-processing/3-program <span class="field field--name-title field--type-string field--label-hidden">The 3-A Program</span> <span class="field field--name-uid field--type-entity-reference field--label-hidden"> <span lang="" typeof="schema:Person" property="schema:name" datatype=""> (not verified)</span> </span> <span class="field field--name-created field--type-created field--label-hidden">June 22, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-processing.rss" addthis:title="Dairy Processing" addthis:description="The 3-A Symbol Council representing a cross-section of industry establishes the intended use of a piece of milk handling/processing equipment and then affixes established criteria or standards upon its fabrication and design. This then provides a guide to a manufacturer and fabricator and a legal document. Each standard defines the applicable product, the product contact surface, and the non-product contact surfaces applicable to the piece of equipment. The definitions also define fabricating materials which are predominantly limited to the 300 series of stainless steel. The application and usage of the equipment is so rigid that the introduction of alternative materials is nearly impossible. This maintains strict control of the fabricating materials to the adherence with the written standard. In fabrication, strict limitations are placed on sharp internal corners by specifying minimum radius requirements. The standards also have provisions for bonding and welding, accessibility of surfaces, self-draining characteristics, protection of product through using overlapping covers, gasket groove dimensions, elimination of threads in the product zones, floor clearance, etc. The standards also provide specific details of fabrication and workmanship criteria and specifies a No. 4 finish which is equated to a surface polished by 150 grit silicon carbide abrasive. The standard does permit a 2-B finish limited to applications for contact with dry milk products. This concept of &quot;smooth&quot; finish is directly related to the effective cleanability of the surface. ADVANTAGES OF A 3-A SANITARY STANDARDS PROGRAM The program gives assurance to the dairy processor that they are in compliance with applicable sanitation codes if the equipment and components meet 3-A Standards. Consequently, individual inspection of equipment for sanitary design is often unnecessary when it complies with 3-A Standards. The sanitary design demanded by 3-A approved equipment also assures the processor that the most modern cleaning and sanitizing methods, materials and systems can be applied without damage to equipment or residue carry-over to product. The phrase &quot;under the environment of intended use&quot; connotes the preservation of a cleanable surface throughout repeated exposure to product contact and the cleaning and sanitizing environment. The dairy processor therefore has increased ease of and efficiency in equipment cleanability which converts to lower cleaning cost, and savings in labor. For the equipment manufacturer, assurance is provided that their equipment if designed in conformance with 3-A Standards will receive automatic acceptance from processors and sanitarians. Finally the 3-A Council has promoted studies which has resulted in significant contributions to the state of the art equipment and pioneered criteria for cleanability of multiple-use plastics and plastic tubing. THE 3-A SYMBOL COUNCIL Equipment manufactured in conformity with 3-A Sanitary Standards complies with the sanitary design and construction standards of this Ordinance. The 3-A Council authorizes equipment manufacturers and fabricators to display their nationally recognized symbol on all equipment that has been certified to be in compliance with the established guidelines. Equipment standards are published biennially by the International Association for Milk, Food, and Environmental Sanitarians with the serial number of the applicable standard. The use of 3-A Sanitary Standards helps to promote uniformity and resolves many of the problems of conflicting codes and individual regulatory criteria. Involved in the establishment of the standards is the International Association for Milk, Food, and Environmental Sanitarians, the Dairy Industry Sanitary Standards Committee, The Milk Industry Foundation, the Dairy and Food Industry Supply Association and the U. S. Public Health Service Food and Drug Administration. The appointed Trustees of the 3-A Symbol Council consists of Dairy Equipment Suppliers (2 representatives), Dairy Processors (2 representatives), and Milk Sanitarians (4 representatives). "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "The 3-A Symbol Council representing a cross-section of industry establishes the intended use of a piece of milk handling/processing equipment and then affixes established criteria or standards upon its fabrication and design. This then provides a guide to a manufacturer and fabricator and a legal document." } } </script> <a class="addthis_button_twitter"></a> <a class="addthis_button_email"></a> <a class="addthis_button_compact"></a> </div> <div class="clearfix text-formatted field field--name-body field--type-text-with-summary field--label-hidden field__item"><p>The 3-A Symbol Council representing a cross-section of industry establishes the intended use of a piece of milk handling/processing equipment and then affixes established criteria or standards upon its fabrication and design. This then provides a guide to a manufacturer and fabricator and a legal document.</p> <p>Each standard defines the applicable product, the product contact surface, and the non-product contact surfaces applicable to the piece of equipment. The definitions also define fabricating materials which are predominantly limited to the 300 series of stainless steel. The application and usage of the equipment is so rigid that the introduction of alternative materials is nearly impossible. This maintains strict control of the fabricating materials to the adherence with the written standard.</p> <p>In fabrication, strict limitations are placed on sharp internal corners by specifying minimum radius requirements. The standards also have provisions for bonding and welding, accessibility of surfaces, self-draining characteristics, protection of product through using overlapping covers, gasket groove dimensions, elimination of threads in the product zones, floor clearance, etc. The standards also provide specific details of fabrication and workmanship criteria and specifies a No. 4 finish which is equated to a surface polished by 150 grit silicon carbide abrasive. The standard does permit a 2-B finish limited to applications for contact with dry milk products. This concept of "smooth" finish is directly related to the effective cleanability of the surface.</p> <h4><strong>ADVANTAGES OF A 3-A SANITARY STANDARDS PROGRAM</strong></h4> <p>The program gives assurance to the dairy processor that they are in compliance with applicable sanitation codes if the equipment and components meet 3-A Standards. Consequently, individual inspection of equipment for sanitary design is often unnecessary when it complies with 3-A Standards. The sanitary design demanded by 3-A approved equipment also assures the processor that the most modern cleaning and sanitizing methods, materials and systems can be applied without damage to equipment or residue carry-over to product.</p> <p>The phrase "under the environment of intended use" connotes the preservation of a cleanable surface throughout repeated exposure to product contact and the cleaning and sanitizing environment. The dairy processor therefore has increased ease of and efficiency in equipment cleanability which converts to lower cleaning cost, and savings in labor.</p> <p>For the equipment manufacturer, assurance is provided that their equipment if designed in conformance with 3-A Standards will receive automatic acceptance from processors and sanitarians.</p> <p>Finally the 3-A Council has promoted studies which has resulted in significant contributions to the state of the art equipment and pioneered criteria for cleanability of multiple-use plastics and plastic tubing.</p> <h4><strong>THE 3-A SYMBOL COUNCIL</strong></h4> <p>Equipment manufactured in conformity with 3-A Sanitary Standards complies with the sanitary design and construction standards of this Ordinance.</p> <p>The 3-A Council authorizes equipment manufacturers and fabricators to display their nationally recognized symbol on all equipment that has been certified to be in compliance with the established guidelines.</p> <p>Equipment standards are published biennially by the International Association for Milk, Food, and Environmental Sanitarians with the serial number of the applicable standard. The use of 3-A Sanitary Standards helps to promote uniformity and resolves many of the problems of conflicting codes and individual regulatory criteria.</p> <p>Involved in the establishment of the standards is the International Association for Milk, Food, and Environmental Sanitarians, the Dairy Industry Sanitary Standards Committee, The Milk Industry Foundation, the Dairy and Food Industry Supply Association and the U. S. Public Health Service Food and Drug Administration.</p> <p>The appointed Trustees of the 3-A Symbol Council consists of Dairy Equipment Suppliers (2 representatives), Dairy Processors (2 representatives), and Milk Sanitarians (4 representatives).</p> </div> <div class="field field--name-field-sf-article-category field--type-entity-reference field--label-above"> <div class="field__label">Category</div> <div class="field__item"><a href="/articles/dairy-processing/dairy-processing-information" hreflang="en">Dairy Processing Information</a></div> </div> Thu, 22 Jun 2017 22:49:38 +0000 Anonymous 386 at https://drinc.ucdavis.edu How to Cut Waste to Reduce Surcharges for Your Dairy https://drinc.ucdavis.edu/dairy-processing/how-cut-waste-reduce-surcharges-your-dairy <span class="field field--name-title field--type-string field--label-hidden">How to Cut Waste to Reduce Surcharges for Your Dairy</span> <span class="field field--name-uid field--type-entity-reference field--label-hidden"> <span lang="" typeof="schema:Person" property="schema:name" datatype=""> (not verified)</span> </span> <span class="field field--name-created field--type-created field--label-hidden">June 22, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-processing.rss" addthis:title="Dairy Processing" addthis:description="Did you know that your dairy plant may be producing a waste load of 800,000 pounds of BOD5 per year - equivalent to the load from a city of 13,000 people? Wastewater from most dairy plants is discharged to publicly owned treatment works (POTWs), where the majority of the pollutants are removed before the water is discharged to the environment. Treating the water costs money, and most treatment works charge according to the volume of sewage treated. In addition, they commonly charge extra (apply a surcharge) if the waste load exceeds certain specified levels because it costs more to treat water that contains more pollutants. Waste load can be determined by a number of different measurements, including BOD5, the biochemical oxygen demand; COD, the chemical oxygen demand, TSS, the total suspended solids concentration, TKN, the total Kjeldahl nitrogen content, and FOG, the concentration of fats, oils, and grease. Wastewater from dairy plants is most often tested for BOD5, a measure of the amount of oxygen needed to degrade the organic matter carried by the water. The BOD5 concentration is measured in milligrams per liter (mg/l). When the level exceeds 250 to 300 mg/l, many treatment plants apply a surcharge. Some dairy plants discharge as much as 12 pounds of BOD5 per 1,000 pounds of milk received. More than 90 percent of a plant&#039;s total waste load comes from milk components that are lost and flow into floor drains during processing. Lactose, proteins, and butterfat are the major components. The wastewater may also contain cleaning agents, lubricants, and solids removed from equipment and floors. Waste Loads Can Affect Profits In the past, most dairy plant managers did not concern themselves with reducing their plant&#039;s waste load because treatment costs were minimal and restrictions few. Over the past 25 years, however, some cities have increased their surcharges ninefold. BOD5 surcharges now exceed 30 cents per pound in some cities. Pretreatment ordinances in some localities may limit the level of wastes that can be discharged into the sewers. In that case the waste load must be reduced before the wastewater leaves the dairy plant. Sewer costs, once a minor operating expense, have become something that every cost-conscious manager must consider. At today&#039;s rates, a plant&#039;s waste load can have a real effect on profitability. Realizing this, some plant managers have been able to cut waste discharges to as little as 1 pound of BOD5 per thousand pounds of milk received. Calculating Your Surcharge The total amount of BOD5 in a plant&#039;s wastewater can be calculated by multiplying the BOD5 concentration in milligrams per liter by the amount of effluent in millions of gallons  Amount of BOD5 = 8.34 x BOD5 concentration x effluent volume For example, if a plant discharges 3.7 million gallons of wastewater per month with a BOD5 concentration of 2,300 mg/l, the total amount of BOD5 discharged during the month is calculated as follows: Amount of BOD5 = 8.34 x 2,300 x 3.7 = 70,973 pounds In addition to the charge for excess BOD5, surcharges may also be made for excessively high levels of COD, TSS, FOG, and TKN. Saving Money by Cutting Waste Load: An Example How much money could a dairy plant save by reducing its BOD5 load to only 1 pound per thousand pounds of milk? To find out, consider two dairy plants that each process 645,000 pounds of milk per day. Both pay a BOD5 surcharge of 20 cents per pound. Processor A discharges 1 pound of BOD5 per thousand pounds of milk processed (1 pound for every 116 gallons), while Processor B discharges 5 pounds in processing the same amount of milk. The table shows the daily and annual surcharge costs for the two plants. The operators of Plant A save 80 cents per thousand pounds of milk processed. That means they can bank an extra $516 per day, or almost $130,000 annually if the plant operates 250 days each year. In effect, Processor B is pouring that amount of money down the drain. Sewer Surcharge Comparison for Two Dairy Plants Processing 645,000 Pounds (75,000 gallons) of Milk per Day   Plant A Plant B Savings Waste load (lb of BOD5 per thousand lb of milk) 1 5 4 Daily BOD5 surcharge $129 $645 $516 Annual Surcharge $32,250 $161,250 $129,000 Cost per thousand pounds of milk processed $0.20 $1.00 $0.80 Cost per thousand gallons of milk processed $1.72 $8.60 $6.88 It is also important to remember that the excess waste load reflects milk lost during processing, and the cost of this lost product must be added to the surcharge to find the true cost. To estimate the potential savings for your plant, determine the sewer surcharges in your community and the current waste load produced by your plant per thousand pounds of milk processed. Then calculate the amount you think the waste load could be decreased by improved operating practices. Enter the values in the work sheet to compute your savings. Sewer Surcharge Savings for Your Plant   Current Target Enter current and target waste load in pounds of BOD5 per thousand pounds of milk processed     Enter daily production in thousands of pounds of milk     Multiply current and target waste loads by daily production to find daily waste load in pounds     Enter your BOD5 surcharge cost per pound     Multiply the daily waste load by the surcharge cost to find your daily surcharge cost     Enter the number of days your plant operates each year     Multiply the daily surcharge cost by the number of days your plant operates annually to find the annual surcharge cost     Subtract the annual surcharge cost for the target waste load from the annual cost for the current waste load to find your annual savings     You Can Reduce Waste Load and Save Money in Your Plant You can take positive steps to reduce the waste load produced by your plant. Some suggestions are given in the box. To keep tabs on your progress, use the work sheet to calculate your plant’s waste load. You’ll not only help protect the environment, you’ll also show the people in your community that your firm is a responsible corporate citizen. AND you will send more money to the bank instead of down the drain. Waste Reduction Hints Make waste reduction a management priority. Establish waste load reduction goals for your plant. Establish waste load reduction goals for all important processes and areas of the plant where waste can be monitored and controlled. Improve maintenance to prevent product leaks from valves, piping, and equipment. Reduce water use; remember that water used in processing becomes wastewater that must be treated. Thoroughly drain product from tanks and vats before cleaning. Collect solids from floors and equipment by sweeping. Shovel the wastes into containers before actual cleanup begins. Do not use hoses as brooms. Adopt the attitude that waste load reduction is one of the best managerial decisions you can make. Orient employees toward preventing pollution, and train them how to do their jobs in a way that will reduce the discharge of wastes from your plant. "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "Did you know that your dairy plant may be producing a waste load of 800,000 pounds of BOD5 per year - equivalent to the load from a city of 13,000 people?" } } </script> <a class="addthis_button_twitter"></a> <a class="addthis_button_email"></a> <a class="addthis_button_compact"></a> </div> <div class="clearfix text-formatted field field--name-body field--type-text-with-summary field--label-hidden field__item"><p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Did you know that your dairy plant may be producing a waste load of 800,000 pounds of BOD5 per year - equivalent to the load from a city of 13,000 people?</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Wastewater from most dairy plants is discharged to publicly owned treatment works (POTWs), where the majority of the pollutants are removed before the water is discharged to the environment. Treating the water costs money, and most treatment works charge according to the volume of sewage treated. In addition, they commonly charge extra (apply a surcharge) if the waste load exceeds certain specified levels because it costs more to treat water that contains more pollutants.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Waste load can be determined by a number of different measurements, including BOD5, the biochemical oxygen demand; COD, the chemical oxygen demand, TSS, the total suspended solids concentration, TKN, the total Kjeldahl nitrogen content, and FOG, the concentration of fats, oils, and grease.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Wastewater from dairy plants is most often tested for BOD5, a measure of the amount of oxygen needed to degrade the organic matter carried by the water. The BOD5 concentration is measured in milligrams per liter (mg/l). When the level exceeds 250 to 300 mg/l, many treatment plants apply a surcharge.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Some dairy plants discharge as much as 12 pounds of BOD5 per 1,000 pounds of milk received. More than 90 percent of a plant's total waste load comes from milk components that are lost and flow into floor drains during processing. Lactose, proteins, and butterfat are the major components. The wastewater may also contain cleaning agents, lubricants, and solids removed from equipment and floors.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <div> <h3><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Waste Loads Can Affect Profits</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h3> </div> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>In the past, most dairy plant managers did not concern themselves with reducing their plant's waste load because treatment costs were minimal and restrictions few. Over the past 25 years, however, some cities have increased their surcharges ninefold. BOD5 surcharges now exceed 30 cents per pound in some cities. Pretreatment ordinances in some localities may limit the level of wastes that can be discharged into the sewers. In that case the waste load must be reduced before the wastewater leaves the dairy plant.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Sewer costs, once a minor operating expense, have become something that every cost-conscious manager must consider. At today's rates, a plant's waste load can have a real effect on profitability. Realizing this, some plant managers have been able to cut waste discharges to as little as 1 pound of BOD5 per thousand pounds of milk received.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <h3><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Calculating Your Surcharge</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></h3> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>The total amount of BOD5 in a plant's wastewater can be calculated by multiplying the BOD5 concentration in milligrams per liter by the amount of effluent in millions of gallons </span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <div> <ul><li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Amount of BOD5 = 8.34 x BOD5 concentration x effluent volume</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>For example, if a plant discharges 3.7 million gallons of wastewater per month with a BOD5 concentration of 2,300 mg/l, the total amount of BOD5 discharged during the month is calculated as follows:</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> <li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Amount of BOD5 = 8.34 x 2,300 x 3.7 = 70,973 pounds</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> </ul></div> <p>In addition to the charge for excess BOD5, surcharges may also be made for excessively high levels of COD, TSS, FOG, and TKN.</p> <h3>Saving Money by Cutting Waste Load: An Example</h3> <p>How much money could a dairy plant save by reducing its BOD5 load to only 1 pound per thousand pounds of milk? To find out, consider two dairy plants that each process 645,000 pounds of milk per day. Both pay a BOD5 surcharge of 20 cents per pound. Processor A discharges 1 pound of BOD5 per thousand pounds of milk processed (1 pound for every 116 gallons), while Processor B discharges 5 pounds in processing the same amount of milk.</p> <p>The table shows the daily and annual surcharge costs for the two plants. The operators of Plant A save 80 cents per thousand pounds of milk processed. That means they can bank an extra $516 per day, or almost $130,000 annually if the plant operates 250 days each year. In effect, Processor B is pouring that amount of money down the drain.</p> <p>Sewer Surcharge Comparison for Two Dairy Plants Processing 645,000 Pounds (75,000 gallons) of Milk per Day</p> <div> <table><tbody><tr><td> </td> <td>Plant A</td> <td>Plant B</td> <td>Savings</td> </tr><tr><td>Waste load (lb of BOD5 per thousand lb of milk)</td> <td>1</td> <td>5</td> <td>4</td> </tr><tr><td>Daily BOD5 surcharge</td> <td>$129</td> <td>$645</td> <td>$516</td> </tr><tr><td>Annual Surcharge</td> <td>$32,250</td> <td>$161,250</td> <td>$129,000</td> </tr><tr><td>Cost per thousand pounds of milk processed</td> <td>$0.20</td> <td>$1.00</td> <td>$0.80</td> </tr><tr><td>Cost per thousand gallons of milk processed</td> <td>$1.72</td> <td>$8.60</td> <td>$6.88</td> </tr></tbody></table></div> <p>It is also important to remember that the excess waste load reflects milk lost during processing, and the cost of this lost product must be added to the surcharge to find the true cost.</p> <p>To estimate the potential savings for your plant, determine the sewer surcharges in your community and the current waste load produced by your plant per thousand pounds of milk processed. Then calculate the amount you think the waste load could be decreased by improved operating practices. Enter the values in the work sheet to compute your savings.</p> <h3><strong>Sewer Surcharge Savings for Your Plant</strong></h3> <div> <table><tbody><tr><td> </td> <td>Current</td> <td>Target</td> </tr><tr><td>Enter current and target waste load in pounds of BOD5 per thousand pounds of milk processed</td> <td> </td> <td> </td> </tr><tr><td>Enter daily production in thousands of pounds of milk</td> <td> </td> <td> </td> </tr><tr><td>Multiply current and target waste loads by daily production to find daily waste load in pounds</td> <td> </td> <td> </td> </tr><tr><td>Enter your BOD5 surcharge cost per pound</td> <td> </td> <td> </td> </tr><tr><td>Multiply the daily waste load by the surcharge cost to find your daily surcharge cost</td> <td> </td> <td> </td> </tr><tr><td>Enter the number of days your plant operates each year</td> <td> </td> <td> </td> </tr><tr><td>Multiply the daily surcharge cost by the number of days your plant operates annually to find the annual surcharge cost</td> <td> </td> <td> </td> </tr><tr><td>Subtract the annual surcharge cost for the target waste load from the annual cost for the current waste load to find your annual savings</td> <td> </td> <td> </td> </tr></tbody></table></div> <h4>You Can Reduce Waste Load and Save Money in Your Plant</h4> <p>You can take positive steps to reduce the waste load produced by your plant. Some suggestions are given in the box. To keep tabs on your progress, use the work sheet to calculate your plant’s waste load. You’ll not only help protect the environment, you’ll also show the people in your community that your firm is a responsible corporate citizen. AND you will send more money to the bank instead of down the drain.</p> <div> <h4><strong>Waste Reduction Hints</strong></h4> <ul><li>Make waste reduction a management priority.</li> <li>Establish waste load reduction goals for your plant.</li> <li>Establish waste load reduction goals for all important processes and areas of the plant where waste can be monitored and controlled.</li> <li>Improve maintenance to prevent product leaks from valves, piping, and equipment.</li> <li>Reduce water use; remember that water used in processing becomes wastewater that must be treated.</li> <li>Thoroughly drain product from tanks and vats before cleaning.</li> <li>Collect solids from floors and equipment by sweeping. Shovel the wastes into containers before actual cleanup begins. Do not use hoses as brooms.</li> <li>Adopt the attitude that waste load reduction is one of the best managerial decisions you can make.</li> <li>Orient employees toward preventing pollution, and train them how to do their jobs in a way that will reduce the discharge of wastes from your plant.</li> </ul></div> </div> <div class="field field--name-field-sf-article-category field--type-entity-reference field--label-above"> <div class="field__label">Category</div> <div class="field__item"><a href="/articles/dairy-processing/dairy-processing-information" hreflang="en">Dairy Processing Information</a></div> </div> Thu, 22 Jun 2017 22:45:21 +0000 Anonymous 381 at https://drinc.ucdavis.edu What is BOD? https://drinc.ucdavis.edu/dairy-processing/what-bod <span class="field field--name-title field--type-string field--label-hidden">What is BOD?</span> <span class="field field--name-uid field--type-entity-reference field--label-hidden"> <span lang="" typeof="schema:Person" property="schema:name" datatype=""> (not verified)</span> </span> <span class="field field--name-created field--type-created field--label-hidden">June 22, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-processing.rss" addthis:title="Dairy Processing" addthis:description="With the growing importance of effective pollution control, added emphasis has been placed on the Biochemical Oxygen Demand (BOD). The Environmental Protection Agency uses BOD levels to measure effluent strength and to establish effluent guidelines as required by the Federal Water Pollution Control Act. Many municipalities use BOD loads to determine charges and surcharges for industrial users of waste treatment facilities. More importantly, BOD strength is a measure of plant losses during handling and processing of dairy products. Biochemical oxygen demand is a measure of effluent strength in terms of the amount of dissolved oxygen utilized by microorganisms during the oxidation of organic components in the effluent. BOD is determined by incubating a suitable dilution of effluent in a standard dilution water or specific composition at 68°F. After incubation, the amount of dissolved oxygen consumed is obtained by titration and the results expressed as parts per million of BOD. Complete biological oxidation generally requires about 20 days at 68°F. However, the test has been standardized to be completed in 5 days, hence the term BOD5. If no inhibiting substances are present, the oxidation of milk solids is approximately 68-70% complete in 5 days. Knowledge of BOD5 in parts per million of dissolved oxygen and the volume of effluent permits the calculations of pounds of BOD. the pounds of BOD can be calculated by the formula:  Pounds of BOD5 = gallons of water x 8.34 x ppm BOD5 . If the exact composition of the effluent is known, the pounds of BOD5 can be calculated quite easily by applying the factors 1.031, 0.890, and 0.691 for protein, fat, and carbohydrate, respectively. The exact composition of effluent is rarely known. However, the amount of BOD5 possessed by common processing materials can be calculated from known composition. For example, the BOD5 of 100 pounds of milk containing 3.25% protein, 3.6% fat and 5.0% lactose would be 10.00. The calculation is made as follows:   Pounds of Component Pounds of Milk % Component Factor Total Protein Fat Lactose 100 100 100 3.25 3.60 5.00 3.25 3.60 5.00 1.031 0.890 0.691 3.35075 3.204 3.455 Total BOD5 10.00975 This type of calculation can be used to determine the amount of BOD5 in any product. The calculation is an approximation and will differ somewhat from BOD5 levels determined in the laboratory. However, they are sufficiently accurate to estimate the potential contribution of a processing ingredient to the total waste load. "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "With the growing importance of effective pollution control, added emphasis has been placed on the Biochemical Oxygen Demand (BOD). The Environmental Protection Agency uses BOD levels to measure effluent strength and to establish effluent guidelines as required by the Federal Water Pollution Control Act. Many municipalities use BOD loads to determine charges and surcharges for industrial users of waste treatment facilities." } } </script> <a class="addthis_button_twitter"></a> <a class="addthis_button_email"></a> <a class="addthis_button_compact"></a> </div> <div class="clearfix text-formatted field field--name-body field--type-text-with-summary field--label-hidden field__item"><p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>With the growing importance of effective pollution control, added emphasis has been placed on the Biochemical Oxygen Demand (BOD). The Environmental Protection Agency uses BOD levels to measure effluent strength and to establish effluent guidelines as required by the Federal Water Pollution Control Act. Many municipalities use BOD loads to determine charges and surcharges for industrial users of waste treatment facilities. More importantly, BOD strength is a measure of plant losses during handling and processing of dairy products.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Biochemical oxygen demand is a measure of effluent strength in terms of the amount of dissolved oxygen utilized by microorganisms during the oxidation of organic components in the effluent. BOD is determined by incubating a suitable dilution of effluent in a standard dilution water or specific composition at 68°F. After incubation, the amount of dissolved oxygen consumed is obtained by titration and the results expressed as parts per million of BOD. Complete biological oxidation generally requires about 20 days at 68°F. However, the test has been standardized to be completed in 5 days, hence the term BOD5. If no inhibiting substances are present, the oxidation of milk solids is approximately 68-70% complete in 5 days.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Knowledge of BOD5 in parts per million of dissolved oxygen and the volume of effluent permits the calculations of pounds of BOD. the pounds of BOD can be calculated by the formula: </span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <div> <ul><li><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Pounds of BOD5 = gallons of water x 8.34 x ppm BOD5 .</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></li> </ul></div> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>If the exact composition of the effluent is known, the pounds of BOD5 can be calculated quite easily by applying the factors 1.031, 0.890, and 0.691 for protein, fat, and carbohydrate, respectively. The exact composition of effluent is rarely known. However, the amount of BOD5 possessed by common processing materials can be calculated from known composition. For example, the BOD5 of 100 pounds of milk containing 3.25% protein, 3.6% fat and 5.0% lactose would be 10.00.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><strong>The calculation is made as follows:</strong></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> <div> <table><tbody><tr><td> </td> <td><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Pounds of Component</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></td> <td><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Pounds of Milk</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></td> <td><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>% Component</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></td> <td><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Factor</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></td> <td><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Total</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></td> </tr><tr><td><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Protein<br /> Fat<br /> Lactose</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></td> <td> <div><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>100<br /> 100<br /> 100</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></div> </td> <td> <div><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>3.25<br /> 3.60<br /> 5.00</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></div> </td> <td> <div><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>3.25<br /> 3.60<br /> 5.00</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></div> </td> <td> <div><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>1.031<br /> 0.890<br /> 0.691</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></div> </td> <td> <div><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>3.35075<br /> 3.204<br /> 3.455</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></div> </td> </tr><tr><td><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>Total BOD5</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></td> <td><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>10.00975</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></td> </tr></tbody></table></div> <p><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span><span>This type of calculation can be used to determine the amount of BOD5 in any product. The calculation is an approximation and will differ somewhat from BOD5 levels determined in the laboratory. However, they are sufficiently accurate to estimate the potential contribution of a processing ingredient to the total waste load.</span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></span></p> </div> <div class="field field--name-field-sf-article-category field--type-entity-reference field--label-above"> <div class="field__label">Category</div> <div class="field__item"><a href="/articles/dairy-processing/dairy-processing-information" hreflang="en">Dairy Processing Information</a></div> </div> Thu, 22 Jun 2017 22:44:29 +0000 Anonymous 376 at https://drinc.ucdavis.edu FDA Nutrient Content Descriptors https://drinc.ucdavis.edu/dairy-processing/fda-nutrient-content-descriptors <span class="field field--name-title field--type-string field--label-hidden">FDA Nutrient Content Descriptors</span> <span class="field field--name-uid field--type-entity-reference field--label-hidden"> <span lang="" typeof="schema:Person" property="schema:name" datatype=""> (not verified)</span> </span> <span class="field field--name-created field--type-created field--label-hidden">June 22, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-processing.rss" addthis:title="Dairy Processing" addthis:description="Free A serving contains no or a physiologically inconsequential amount: "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "Free A serving contains no or a physiologically inconsequential amount: &amp;lt;5 calories; &amp;lt;0.5 g of fat; &amp;lt;0.5 g of saturated fat; &amp;lt;5 mg sodium; or &amp;lt;2mg of cholesterol. Low A serving (and 50g of food if the serving size is small) contains no more than 40 calories; 3g of fat; 1g of saturated fat and 15% of calories from saturated fat; or 20mg of cholesterol; or 140 mg sodium. Reduced or Less A nutritionally altered product contains 25% less of a nutrient or 25% fewer cal" } } </script> <a class="addthis_button_twitter"></a> <a class="addthis_button_email"></a> <a class="addthis_button_compact"></a> </div> <div class="clearfix text-formatted field field--name-body field--type-text-with-summary field--label-hidden field__item"><dl><dt><strong>Free</strong></dt> <dd>A serving contains no or a physiologically inconsequential amount: &lt;5 calories; &lt;0.5 g of fat; &lt;0.5 g of saturated fat; &lt;5 mg sodium; or &lt;2mg of cholesterol.</dd> <dt><strong>Low</strong></dt> <dd>A serving (and 50g of food if the serving size is small) contains no more than 40 calories; 3g of fat; 1g of saturated fat and 15% of calories from saturated fat; or 20mg of cholesterol; or 140 mg sodium.</dd> </dl><dl><dt><strong>Reduced or Less</strong></dt> <dd>A nutritionally altered product contains 25% less of a nutrient or 25% fewer calories than a reference food; cannot be used if the reference food already meets the requirement for "low" claim.</dd> </dl><dl><dt><strong>Less</strong></dt> <dd>A food contains 25% less of a nutrient or 25% fewer calories than a reference food.</dd> </dl><dl><dt><strong>Light</strong></dt> <dd>An altered product contains one-third fewer calories or 50% of the fat in a reference food; if 50% or more of the calories come from fat, the reduction must be 50% of the fat. Light in sodium, must contain 50% less sodium.</dd> </dl><dl><dt><strong>% Fat Free</strong></dt> <dd>A product must be low-fat, and the percentage must accurately reflect the amount of fat in 100g of food. Thus, 2.5g of fat in 50g of food results in a "95% fat-free" claim.</dd> </dl><dl><dt><strong>Healthy</strong></dt> <dd>A food is low in fat and saturated fat, and a serving contains no more than 480 mg of sodium and no more than 60 mg of cholesterol. And the food contains at least 10% RDI or RDV of either vitamin A, vitamin C, calcium, iron, protein or fiber per reference amount and per labeled serving.</dd> </dl><dl><dt><strong>High Fiber</strong></dt> <dd>Must contain 5 g or more fiber. High, rich in or excellent source may be used if the food contains 20% or more of the RDI for protein, vitamins or minerals or 20% or more RDV for dietary fiber or potassium.</dd> </dl><dl><dt><strong>Good Source</strong></dt> <dd>10% of RDV for the nutrient.</dd> </dl><dl><dt><strong>More</strong></dt> <dd>Must contain 10% more of protein, vitamins, potassium, minerals or fiber than the RDV of the reference food.</dd> </dl> </div> <div class="field field--name-field-sf-article-category field--type-entity-reference field--label-above"> <div class="field__label">Category</div> <div class="field__item"><a href="/articles/dairy-processing/dairy-processing-information" hreflang="en">Dairy Processing Information</a></div> </div> Thu, 22 Jun 2017 22:43:13 +0000 Anonymous 371 at https://drinc.ucdavis.edu Agricultural Marketing Service Dairy Division: Grading https://drinc.ucdavis.edu/dairy-processing/agricultural-marketing-service-dairy-division-grading <span class="field field--name-title field--type-string field--label-hidden">Agricultural Marketing Service Dairy Division: Grading</span> <span class="field field--name-uid field--type-entity-reference field--label-hidden"> <span lang="" typeof="schema:Person" property="schema:name" datatype=""> (not verified)</span> </span> <span class="field field--name-created field--type-created field--label-hidden">June 22, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-processing.rss" addthis:title="Dairy Processing" addthis:description="Agricultural Marketing Service Program Objectives To assist the dairy industry in marketing high-quality dairy products by providing buyers and sellers with an impartial appraisal of product quality and to provide the consumer confidence in buying. The following two sections provide an overview of Grading. Benefits of the Program Program Operations Plant inspections and equipment reviews Inspection and grading Dairy product grades and quality approval Resident grading and quality control Benefits of the Program Provides buyers and sellers with an impartial appraisal of product quality Stimulates manufacturers to produce uniformly high-quality, stable products Assures the quality of dairy products so consumers can buy with confidence Program Operations Official dairy product grading is recognized by dairy producers, processors, wholesalers, buyers, food service industry, and others as a vital link in their marketing chain. The use of dairy grades and certifications is also increasing internationally. Inspection and grading activities are carried out through four major programs which help to improve the quality, manufacture, and distribution of dairy products -- plant inspections and equipment reviews, inspection and grading, dairy product grades and quality approval, and resident grading and quality control. Plant inspections and equipment reviews Inspection and grading services assure the quality of dairy products and are offered to the dairy industry on a voluntary basis. Official approval of a manufacturing plant is a prerequisite for grading. Therefore, a consumer can tell if the products were produced in a USDA-approved plant by looking for the grade shield on products such as butter, Cheddar cheese, and instant nonfat dry milk. The shield means that every lot has been certified by an inspector as meeting the grade requirements. It does not necessarily apply to all manufactured products, but only to the specific product on which it appears. Only after an inspection shows that a plant has substantially met the requirements outlined in USDA&#039;s General Specifications for Approved Dairy Plants can the plant qualify for the other services of grading, sampling, testing, and certification of its product. This inspection tells a plant manager about the quality of raw material, sanitation, condition of plant and equipment, and processing procedures--factors affecting the quality and wholesomeness of the finished product. The plant manager may use the inspection findings to assure customers of safe, uniform, high-quality products. A dairy inspector conducts each plant inspection. Each inspection is tailored to the nature of the plant. The inspector meets with the plant manager to review the survey results. If any deficiencies exist, the inspector explains to the plant manager the steps to be taken before approval can be granted. After corrections are made, the inspector makes another inspection before granting an &quot;approved&quot; status. Once approved, a plant does not automatically keep its status. A plant must be inspected at least twice a year to maintain its eligibility. Equipment and process reviews are based on an examination of engineering drawings or of actual equipment, often with the participation of design engineers. This program is closely associated with the Plant Inspection Program. Most of the review activity concerns newly developed technology and machines for which guidance and policy must be developed. Dairy Division staff members also participate in the efforts of the 3-A Sanitary Standards Committees for the development of dairy equipment standards. Dairy product grades and quality approval Inspection and Grading Grades are based on nationally uniform standards developed by Dairy Division experts in cooperation with industry representatives. Sellers can request grading services to assure that products meet specific grade or contract requirements and have good keeping quality properties. Buyers can request grading services to assure that products have uniform high quality. Those wishing to use the services must request them, qualify for them, and pay a fee commensurate with the cost of providing them. Two examples of such services are the grade label program for butter and Cheddar cheese, and the acceptance service for volume buyers. Under the grade label program, consumer packages bear an official identification indicating the U.S. grade. As a part of the acceptance service, the user has all deliveries examined by USDA to certify that they meet specifications. All dairy products offered for sale to the Federal Government under the dairy price support program or sanctioned under such programs as the Dairy Export Incentive Program (DEIP) are inspected by AMS&#039; dairy graders. This assures compliance with purchase announcement specifications and helps assure that the products will maintain their quality. The stocks of Government-owned dairy products are inspected periodically to ensure that quality has not deteriorated during storage. Dairy product grades and quality approval Almost all dairy products can be graded, but the service is used most widely for butter, Cheddar cheese, instant nonfat dry milk, and regular nonfat dry milk. Inspectors also grade other cheeses, dry whey, dry buttermilk, and dried and condensed milk. There are three grades for butter: U.S. Grades AA, A, and B. The ratings are assigned on the basis of flavor, body, and color. The quality of the cream from which the butter is made determines the flavor factor in assigning the grades. There are four grades for Cheddar cheese: U.S. Grades AA, A, B, and C. As with butter, all grades may be used in the wholesale trade, but only the top grade is used at the retail level. To rate the top grade, the cheese must have a consistently fine Cheddar flavor. In addition, there are grades for Swiss cheese, Emmentaler, Colby, Monterey (Monterey Jack), and Bulk American cheese for manufacturing. If instant nonfat dry milk meets the standard for quality, it may carry the U.S. Extra grade shield. This means that laboratory tests show that it possesses a sweet and pleasing flavor, a natural color, and satisfactory solubility. USDA inspectors also check the instant milk for other quality factors such as moisture, fat, bacteria, scorched particles, and acidity. Dry buttermilk and regular nonfat dry milk, which are sold in bulk to producers of ice cream, bakery products, and some processed meat processors, can be graded either U.S. Extra or U.S. Standard. The lower grade, &quot;Standard,&quot; may be the result of excess moisture or scorched particles from the drying process or certain other quality factors. The grades of U.S. Extra and U.S. Standard for dry whole milk are based on quality factors like those for other dry dairy products. Grade requirements for dry whole milk also include a maximum bacteria content. Bacteria limits are designed to ensure a safe product that has good keeping quality. Dry whey--a coproduct in the making of natural cheese--is tested for flavor, appearance, amount of milkfat, and moisture. It must have a good, sweet taste to earn the U.S. Extra grade. Whey of this top quality is desired by manufacturers because it is used as an ingredient in other foods. For cottage cheese, processed cheese, cream cheese, or any other dairy product for which no U.S. grade standards have been established, there is a USDA program for official quality approval. Such products may earn the &quot;Quality Approved&quot; rating, which is based on a USDA inspection of the product and the plant where the product was made. The product must be wholesome and measure up to a specific level of quality to earn the rating. The &quot;Quality Approved&quot; shield may be used on retail packages. Resident grading and quality control Resident grading and quality control service is available to approved plants. This service is a combination of the plant inspection, laboratory programs, and inspection and grading. It provides for quality checks on sanitation, grading, and certification of the finished product by an inspector stationed at the plant on a full-time basis. To qualify for USDA resident grading and quality control service, a dairy plant must first be approved under the plant inspection program. The plant must have a USDA-approved laboratory, which the resident inspector uses for chemical and bacteriological testing of raw ingredients and finished products. The inspector also provides a broad range of facilities and equipment evaluations, for example, the sanitation of processing equipment and the pasteurizing temperature of milk or cream prior to its use in manufacturing. "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "To assist the dairy industry in marketing high-quality dairy products by providing buyers and sellers with an impartial appraisal of product quality and to provide the consumer confidence in buying. " } } </script> <a class="addthis_button_twitter"></a> <a class="addthis_button_email"></a> <a class="addthis_button_compact"></a> </div> <div class="clearfix text-formatted field field--name-body field--type-text-with-summary field--label-hidden field__item"><p><a href="http://www.ams.usda.gov/">Agricultural Marketing Service</a></p> <div> <h3>Program Objectives</h3> <p>To assist the dairy industry in marketing high-quality dairy products by providing buyers and sellers with an impartial appraisal of product quality and to provide the consumer confidence in buying.</p> <p>The following two sections provide an overview of Grading.</p> <ol><li>Benefits of the Program</li> <li>Program Operations</li> <li>Plant inspections and equipment reviews</li> <li>Inspection and grading</li> <li>Dairy product grades and quality approval</li> <li>Resident grading and quality control</li> </ol><h4>Benefits of the Program</h4> <p>Provides buyers and sellers with an impartial appraisal of product quality<br /> Stimulates manufacturers to produce uniformly high-quality, stable products<br /> Assures the quality of dairy products so consumers can buy with confidence</p> <h4>Program Operations</h4> <p>Official dairy product grading is recognized by dairy producers, processors, wholesalers, buyers, food service industry, and others as a vital link in their marketing chain. The use of dairy grades and certifications is also increasing internationally.</p> <p>Inspection and grading activities are carried out through four major programs which help to improve the quality, manufacture, and distribution of dairy products -- plant inspections and equipment reviews, inspection and grading, dairy product grades and quality approval, and resident grading and quality control.</p> <h4>Plant inspections and equipment reviews</h4> <p>Inspection and grading services assure the quality of dairy products and are offered to the dairy industry on a voluntary basis. Official approval of a manufacturing plant is a prerequisite for grading. Therefore, a consumer can tell if the products were produced in a USDA-approved plant by looking for the grade shield on products such as butter, Cheddar cheese, and instant nonfat dry milk. The shield means that every lot has been certified by an inspector as meeting the grade requirements. It does not necessarily apply to all manufactured products, but only to the specific product on which it appears.</p> <p>Only after an inspection shows that a plant has substantially met the requirements outlined in USDA's General Specifications for Approved Dairy Plants can the plant qualify for the other services of grading, sampling, testing, and certification of its product.</p> <p>This inspection tells a plant manager about the quality of raw material, sanitation, condition of plant and equipment, and processing procedures--factors affecting the quality and wholesomeness of the finished product. The plant manager may use the inspection findings to assure customers of safe, uniform, high-quality products.</p> <p>A dairy inspector conducts each plant inspection. Each inspection is tailored to the nature of the plant. The inspector meets with the plant manager to review the survey results. If any deficiencies exist, the inspector explains to the plant manager the steps to be taken before approval can be granted.</p> <p>After corrections are made, the inspector makes another inspection before granting an "approved" status. Once approved, a plant does not automatically keep its status. A plant must be inspected at least twice a year to maintain its eligibility.</p> <p>Equipment and process reviews are based on an examination of engineering drawings or of actual equipment, often with the participation of design engineers. This program is closely associated with the Plant Inspection Program. Most of the review activity concerns newly developed technology and machines for which guidance and policy must be developed. Dairy Division staff members also participate in the efforts of the 3-A Sanitary Standards Committees for the development of dairy equipment standards. Dairy product grades and quality approval</p> <h4>Inspection and Grading</h4> <p>Grades are based on nationally uniform standards developed by Dairy Division experts in cooperation with industry representatives. Sellers can request grading services to assure that products meet specific grade or contract requirements and have good keeping quality properties. Buyers can request grading services to assure that products have uniform high quality. Those wishing to use the services must request them, qualify for them, and pay a fee commensurate with the cost of providing them. Two examples of such services are the grade label program for butter and Cheddar cheese, and the acceptance service for volume buyers. Under the grade label program, consumer packages bear an official identification indicating the U.S. grade. As a part of the acceptance service, the user has all deliveries examined by USDA to certify that they meet specifications.</p> <p>All dairy products offered for sale to the Federal Government under the dairy price support program or sanctioned under such programs as the Dairy Export Incentive Program (DEIP) are inspected by AMS' dairy graders. This assures compliance with purchase announcement specifications and helps assure that the products will maintain their quality. The stocks of Government-owned dairy products are inspected periodically to ensure that quality has not deteriorated during storage.</p> <h4>Dairy product grades and quality approval</h4> <p>Almost all dairy products can be graded, but the service is used most widely for butter, Cheddar cheese, instant nonfat dry milk, and regular nonfat dry milk. Inspectors also grade other cheeses, dry whey, dry buttermilk, and dried and condensed milk.</p> <p>There are three grades for butter: U.S. Grades AA, A, and B. The ratings are assigned on the basis of flavor, body, and color. The quality of the cream from which the butter is made determines the flavor factor in assigning the grades.</p> <p>There are four grades for Cheddar cheese: U.S. Grades AA, A, B, and C. As with butter, all grades may be used in the wholesale trade, but only the top grade is used at the retail level. To rate the top grade, the cheese must have a consistently fine Cheddar flavor. In addition, there are grades for Swiss cheese, Emmentaler, Colby, Monterey (Monterey Jack), and Bulk American cheese for manufacturing.</p> <p>If instant nonfat dry milk meets the standard for quality, it may carry the U.S. Extra grade shield. This means that laboratory tests show that it possesses a sweet and pleasing flavor, a natural color, and satisfactory solubility. USDA inspectors also check the instant milk for other quality factors such as moisture, fat, bacteria, scorched particles, and acidity.</p> <p>Dry buttermilk and regular nonfat dry milk, which are sold in bulk to producers of ice cream, bakery products, and some processed meat processors, can be graded either U.S. Extra or U.S. Standard. The lower grade, "Standard," may be the result of excess moisture or scorched particles from the drying process or certain other quality factors.</p> <p>The grades of U.S. Extra and U.S. Standard for dry whole milk are based on quality factors like those for other dry dairy products. Grade requirements for dry whole milk also include a maximum bacteria content. Bacteria limits are designed to ensure a safe product that has good keeping quality.</p> <p>Dry whey--a coproduct in the making of natural cheese--is tested for flavor, appearance, amount of milkfat, and moisture. It must have a good, sweet taste to earn the U.S. Extra grade. Whey of this top quality is desired by manufacturers because it is used as an ingredient in other foods.</p> <p>For cottage cheese, processed cheese, cream cheese, or any other dairy product for which no U.S. grade standards have been established, there is a USDA program for official quality approval. Such products may earn the "Quality Approved" rating, which is based on a USDA inspection of the product and the plant where the product was made. The product must be wholesome and measure up to a specific level of quality to earn the rating. The "Quality Approved" shield may be used on retail packages.</p> <h4>Resident grading and quality control</h4> <p>Resident grading and quality control service is available to approved plants. This service is a combination of the plant inspection, laboratory programs, and inspection and grading. It provides for quality checks on sanitation, grading, and certification of the finished product by an inspector stationed at the plant on a full-time basis.</p> <p>To qualify for USDA resident grading and quality control service, a dairy plant must first be approved under the plant inspection program. The plant must have a USDA-approved laboratory, which the resident inspector uses for chemical and bacteriological testing of raw ingredients and finished products. The inspector also provides a broad range of facilities and equipment evaluations, for example, the sanitation of processing equipment and the pasteurizing temperature of milk or cream prior to its use in manufacturing.</p> </div> </div> <div class="field field--name-field-sf-article-category field--type-entity-reference field--label-above"> <div class="field__label">Category</div> <div class="field__item"><a href="/articles/dairy-processing/dairy-processing-information" hreflang="en">Dairy Processing Information</a></div> </div> Thu, 22 Jun 2017 22:39:12 +0000 Anonymous 366 at https://drinc.ucdavis.edu Tulare County https://drinc.ucdavis.edu/dairy-processing/tulare-county <span class="field field--name-title field--type-string field--label-hidden">Tulare County</span> <span class="field field--name-uid field--type-entity-reference field--label-hidden"> <span lang="" typeof="schema:Person" property="schema:name" datatype=""> (not verified)</span> </span> <span class="field field--name-created field--type-created field--label-hidden">June 22, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-processing.rss" addthis:title="Dairy Processing" addthis:description="Tulare County "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "Tulare County " } } </script> <a class="addthis_button_twitter"></a> <a class="addthis_button_email"></a> <a class="addthis_button_compact"></a> </div> <div class="clearfix text-formatted field field--name-body field--type-text-with-summary field--label-hidden field__item"><p><a href="http://www.ucce.tulare.ca.us/dairy.htm">Tulare County</a></p> </div> <div class="field field--name-field-sf-article-category field--type-entity-reference field--label-above"> <div class="field__label">Category</div> <div class="field__item"><a href="/articles/dairy-processing/country-dairy-farm-newsletters" hreflang="en">Country Dairy Farm Newsletters</a></div> </div> Thu, 22 Jun 2017 22:38:41 +0000 Anonymous 361 at https://drinc.ucdavis.edu King County https://drinc.ucdavis.edu/dairy-processing/king-county <span class="field field--name-title field--type-string field--label-hidden">King County</span> <span class="field field--name-uid field--type-entity-reference field--label-hidden"> <span lang="" typeof="schema:Person" property="schema:name" datatype=""> (not verified)</span> </span> <span class="field field--name-created field--type-created field--label-hidden">June 22, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-processing.rss" addthis:title="Dairy Processing" addthis:description="King County "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "King County " } } </script> <a class="addthis_button_twitter"></a> <a class="addthis_button_email"></a> <a class="addthis_button_compact"></a> </div> <div class="clearfix text-formatted field field--name-body field--type-text-with-summary field--label-hidden field__item"><p><a href="http://kings.ca.us/kingsce">King County</a></p> </div> <div class="field field--name-field-sf-article-category field--type-entity-reference field--label-above"> <div class="field__label">Category</div> <div class="field__item"><a href="/articles/dairy-processing/country-dairy-farm-newsletters" hreflang="en">Country Dairy Farm Newsletters</a></div> </div> Thu, 22 Jun 2017 22:37:58 +0000 Anonymous 356 at https://drinc.ucdavis.edu