Dairy Food Sciences https://drinc.ucdavis.edu/dairy-food-sciences Dairy Food Sciences for DRINC en Milk Foams for Coffees: To Foam or Not to Foam, That is the Question https://drinc.ucdavis.edu/dairy-food-sciences/milk-foams-coffees-foam-or-not-foam-question-microsoft-word-document <span class="field field--name-title field--type-string field--label-hidden">Milk Foams for Coffees: To Foam or Not to Foam, That is the Question</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 19, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-food-sciences/61/feed" addthis:title="" addthis:description="Background briefing: Steam frothing of milk One of the most common complaints about milk is from coffee shop proprietors whose milk will not froth well when making a cappuccino or other coffee/milk drinks where the milk is foamed.  When milk is frothed for making cappuccino coffee, steam from a steam generator is injected, with air, into the milk to create foam and to heat the milk to near boiling. Both the temperature of the milk and the volume and stability of the foam are important for a good cappuccino. Ideally, some believe that the volume of the frothed-up milk should be more than twice the original volume of the milk, and the foam should be stable for at least 10 minutes, or the time it takes to drink a cup of coffee. Unfortunately, milk sometimes fails to foam during the injection of steam and hence cannot be used for making cappuccino.  Problems Associated with the Farm Raw Milk Lipolysis The most common reason for this is the breakdown of milkfat because of lipolysis, usually before pasteurization. Lipolysis produces free fatty acids, mono-, and diglycerides. It is caused by the action of lipase in the milk, either naturally present or produced by contaminating psychrotrophic bacteria. Mono- and diglycerides are surface-active agents, which depress the frothing capacity of the milk. The steam frothing capacity of milk decreases as the free fatty acid level, the common indicator of lipolysis increases. Lipolysis can occur spontaneously in the milk from some cows when it is cooled soon after milking, and it can be induced by physical treatments of the raw milk such as agitation. The former tends to occur when the cow&#039;s level of nutrition is low and she is in late lactation. The simultaneous occurrence of these factors in herds in addition, throughout regions, is a common cause of the problem. This can happen during a period of adverse weather conditions and/or when cows are seasonally calved. Agitation of milk most commonly occurs at the farm when air leaks into the teat cup cluster and air and warm milk are vigorously mixed in the milking equipment. It also occurs in the factory because of air incorporation when raw milk is pumped excessively.  Mastitis Another factor, which adversely affects steam-frothing capacity, is mastitis. It has been shown that frothing capacity decreases as somatic cell counts increase. At least part of the explanation for this is the amount of proteolysis of casein caused by the natural protease in milk, plasmin, which occurs in elevated levels in mastitis milk. There is some evidence for this since the level of the proteose peptone (fragments of casein produced by plasmin action) in milks is inversely related to frothing ability. In fact, frothing capacity is reduced when protease peptone is added to milk. Producing the Milk Foams The foaming capacity of milk is largely due to the whey proteins, especially lactoblobulin. This globular protein forms a film on the surface of the air bubbles in the foam. When this protein is heated, it denatures, that is unfolds, and is even more efficient in coating and stabilizing the air bubbles. Thus, one way of improving the frothing capacity of milk is to heat it and cool it before trying to froth it. This improvement in frothing is presumably due to the denaturing of the whey proteins. UHT milk whose whey proteins are around 70% denatured froths better than pasteurized milk with around 20% denaturation of the whey proteins. Another process that improves steam frothing is homogenization. The amount of improvement increases as the pressure of homogenization is increased. Pressures around 20 MPa are very effective. Milk solids content has a small effect on frothing capacity and might be of use in some conditions. Although a common practice, adding milk solids, often in the form of skim milk powder, can increase frothing capacity to a limited degree. Commonly held myths about the causes of poor steam frothing: Added water in the milk. Adding water has little effect on frothing. Too much or too little milkfat. The milkfat content has little effect on frothing although skim milk generally gives more froth than milk containing milkfat; however, the froth in skim milk is less dense and subsides more quickly. Due to additives in the milk. Of course, there are no additives in milk. The milk is too fresh. Refrigerated storage of pasteurized milk for up to three days does not affect its frothing capacity. Summary There is insufficient knowledge of steam frothing of milk to provide a definitive understanding of all of the issues that can cause poor frothing. However, raw milk quality is a very important part of ensuring the milk will perform in the coffee shop. Managing the issues outlined will assist in providing the best cappuccino on a daily basis. References Corradini, C. and Innocente, N. (1994) Influence of the proteose peptone fraction on milk foaming capacity. Scienza e Tecnica Lattiero Casearia. 45(2): 107-113. Deeth, H.C. and Smith, R. A. D. (1983) Lipolysis and other factors affecting the steam frothing capacity of milk. Aust. J. Dairy Tech. 38: 14-19. Gambini, G., Castagnetti, G. B. and Losi. G. (1995) Influence of somatic cell count and heat treatments on milk foam formation and stability. Industrie Alimentari. 34:247-252. 6ty. DAIRY INDUSTRY QUALITY CENTRE QUALITY QUARTERLY   Volume 8 No. 3 "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "Background briefing: Steam frothing of milk One of the most common complaints about milk is from coffee shop proprietors whose milk will not froth well when making a cappuccino or other coffee/milk drinks where the milk is foamed. " } } </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">Background briefing: Steam frothing of milk</h2> <p>One of the most common complaints about milk is from coffee shop proprietors whose milk will not froth well when making a cappuccino or other coffee/milk drinks where the milk is foamed. </p> <p>When milk is frothed for making cappuccino coffee, steam from a steam generator is injected, with air, into the milk to create foam and to heat the milk to near boiling. Both the temperature of the milk and the volume and stability of the foam are important for a good cappuccino. Ideally, some believe that the volume of the frothed-up milk should be more than twice the original volume of the milk, and the foam should be stable for at least 10 minutes, or the time it takes to drink a cup of coffee. Unfortunately, milk sometimes fails to foam during the injection of steam and hence cannot be used for making cappuccino. </p> <h3>Problems Associated with the Farm Raw Milk</h3> <h4>Lipolysis</h4> <p>The most common reason for this is the breakdown of milkfat because of lipolysis, usually before pasteurization. Lipolysis produces free fatty acids, mono-, and diglycerides. It is caused by the action of lipase in the milk, either naturally present or produced by contaminating psychrotrophic bacteria.</p> <p>Mono- and diglycerides are surface-active agents, which depress the frothing capacity of the milk. The steam frothing capacity of milk decreases as the free fatty acid level, the common indicator of lipolysis increases. Lipolysis can occur spontaneously in the milk from some cows when it is cooled soon after milking, and it can be induced by physical treatments of the raw milk such as agitation. The former tends to occur when the cow's level of nutrition is low and she is in late lactation. The simultaneous occurrence of these factors in herds in addition, throughout regions, is a common cause of the problem. This can happen during a period of adverse weather conditions and/or when cows are seasonally calved.</p> <p>Agitation of milk most commonly occurs at the farm when air leaks into the teat cup cluster and air and warm milk are vigorously mixed in the milking equipment. It also occurs in the factory because of air incorporation when raw milk is pumped excessively. </p> <h4>Mastitis</h4> <p>Another factor, which adversely affects steam-frothing capacity, is mastitis. It has been shown that frothing capacity decreases as somatic cell counts increase. At least part of the explanation for this is the amount of proteolysis of casein caused by the natural protease in milk, plasmin, which occurs in elevated levels in mastitis milk. There is some evidence for this since the level of the proteose peptone (fragments of casein produced by plasmin action) in milks is inversely related to frothing ability. In fact, frothing capacity is reduced when protease peptone is added to milk.</p> <h4>Producing the Milk Foams</h4> <p>The foaming capacity of milk is largely due to the whey proteins, especially lactoblobulin. This globular protein forms a film on the surface of the air bubbles in the foam. When this protein is heated, it denatures, that is unfolds, and is even more efficient in coating and stabilizing the air bubbles. Thus, one way of improving the frothing capacity of milk is to heat it and cool it before trying to froth it. This improvement in frothing is presumably due to the denaturing of the whey proteins. UHT milk whose whey proteins are around 70% denatured froths better than pasteurized milk with around 20% denaturation of the whey proteins.</p> <p>Another process that improves steam frothing is homogenization. The amount of improvement increases as the pressure of homogenization is increased. Pressures around 20 MPa are very effective.</p> <p>Milk solids content has a small effect on frothing capacity and might be of use in some conditions. Although a common practice, adding milk solids, often in the form of skim milk powder, can increase frothing capacity to a limited degree.</p> <h4>Commonly held myths about the causes of poor steam frothing:</h4> <ol><li>Added water in the milk. Adding water has little effect on frothing.</li> <li>Too much or too little milkfat. The milkfat content has little effect on frothing although skim milk generally gives more froth than milk containing milkfat; however, the froth in skim milk is less dense and subsides more quickly.</li> <li>Due to additives in the milk. Of course, there are no additives in milk.</li> <li>The milk is too fresh. Refrigerated storage of pasteurized milk for up to three days does not affect its frothing capacity.</li> </ol><h3>Summary</h3> <p>There is insufficient knowledge of steam frothing of milk to provide a definitive understanding of all of the issues that can cause poor frothing. However, raw milk quality is a very important part of ensuring the milk will perform in the coffee shop. Managing the issues outlined will assist in providing the best cappuccino on a daily basis.</p> <h3>References</h3> <p><span>Corradini, C. and Innocente, N. (1994<em>) Influence of the proteose peptone fraction on milk foaming capacity</em>. Scienza e Tecnica Lattiero Casearia. 45(2): 107-113.</span></p> <p><span>Deeth, H.C. and Smith, R. A. D. (1983<em>) Lipolysis and other factors affecting the steam frothing capacity of milk</em>. Aust. J. Dairy Tech. 38: 14-19.</span></p> <p><span>Gambini, G., Castagnetti, G. B. and Losi. G. (1995<em>) Influence of somatic cell count and heat treatments on milk foam formation and stability</em>. Industrie Alimentari. 34:247-252. 6ty.</span></p> <p><em><span>DAIRY INDUSTRY QUALITY CENTRE QUALITY QUARTERLY</span></em><span><span>   </span>Volume 8 No. 3</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-food-sciences/dairy-chemistry" hreflang="en">Dairy Chemistry</a></div> </div> Mon, 19 Jun 2017 19:29:27 +0000 Anonymous 121 at https://drinc.ucdavis.edu A Brief Review on Alkaline Phosphatase Methodology https://drinc.ucdavis.edu/dairy-food-sciences/brief-review-alkaline-phosphatase-methodology <span class="field field--name-title field--type-string field--label-hidden">A Brief Review on Alkaline Phosphatase Methodology</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 19, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-food-sciences.rss" addthis:title="Dairy Food Sciences" addthis:description="Enzymes are organic catalysts which occur naturally in most raw foods. When milk is pasteurized most of the enzymes are inactivated or their activity is greatly diminished. The first reliable enzymatic test for determining efficiency of pasteurization was developed by Kay and Graham in England in 1933. It was based upon the inactivation of alkaline phosphatase. The phosphatase test is applied to dairy products to determine whether pasteurization was done properly and also to detect the possible addition of raw milk to pasteurized milk. The thermal resistance of alkaline phosphatase has been considered to be greater than that of any nonsporeforming pathogens that might be found in milk. However, the recent outbreaks of disease traced to Listeria monocytogenes in pasteurized milk lead one to begin to question this conclusion. Alkaline phosphatase is a monesterase that catalyzes the hydrolysis of monoesters. Studies have shown that the amount of alkaline phosphatase in raw milk is variable. The activity of phosphatase per unit of milk seems to be inversely correlated to milk yield, reaching a minimum in 1 or 2 weeks after calving and rising gradually to a maximum in about 25 weeks. Breed, feed of the cow, or fat content of the milk do not appear to influence phosphatase activity. Alkaline phosphatase is associated with the fat globule of milk, i.e., it is adsorbed to the fat globule membrane surface. Phosphatase tests currently described in Standard Methods for the Examination of Dairy Products are based on the principle that the alkaline phosphatase enzyme in raw milk liberates phenol from a disodium phenyl phosphate substrate (Scharer Method) or phenolphthalein from a phenolphthalein monophosphate substrate (Rutgers Method) when tests are conducted at suitable temperature and pH. The amount of phenol or phenolphthalein liberated from the substrate is proportional to the activity of the enzyme. Phenol is measured calorimetrically after its reaction with 2,6 dichloroquinone-chloroimide (CQC) to form indophenol. Phenolphthalein is detected by addition of sodium hydroxide. While the Scharer rapid method is relatively simple and quick, it must be recognized that it does possess some inherent weaknesses. There is a constant hazard of phenol contamination from reagents, glassware, and stoppers. Reagents are unstable as is the color formed by the reaction of phenol with the dye. Visual measurement of color is sometimes difficult, particularly with borderline cases; and emulsification frequently occurs during the extraction of the phenol with butanol. Phenolphthalein monophosphate is a very stable substrate which is easily hydrolyzed by alkaline phosphatase to yield free phenolphthalein. Our studies have revealed that the use of this substrate provides greater sensitivity than disodium phenyl phosphate. The high sensitivity is due to several factors, namely, the ease of color comparison, the high rate of hydrolysis, the elimination of variations because of specific color reaction and extraction, and the slight contribution of yellow color of milk fat to the pink color of phenolphthalein. It is necessary to run both positive and negative controls when conducting a phosphatase procedure. A negative control is prepared by heating a product to 90°C for 1 minute followed by rapid cooling. Any color developing when a test is run on the control indicates contamination of reagents or presence of interfering coloring materials or both. A positive control is run as a check on the proper functioning of reagents. It is conducted by adding 0.2 ml of fresh, raw mixed-herd milk to 100 ml of raw milk which has been heated at 90°C for 1 minute, followed by rapid cooling to room temperature. One should obtain a positive result on this test. Another control test should be run on samples which yield positive results in the initial analysis. This test is conducted in order to distinguish residual alkaline phosphatase from microbial alkaline phosphatase. Microbial phosphatases are considerably more heat resistant than is alkaline milk phosphatase. Therefore, it is possible to differentiate these enzymes by pasteurization of the sample in question and retesting. If there is no significant difference in the results of the test, one then concludes that the original positive result was due to microbial phosphatase. Reactivated phosphatase sometimes occurs in high fat dairy products which have been ultrapasteurized, such reactivation occurring quickly when samples are stored at non-refrigerated (70-90°F) temperatures. A test has been developed which permits one to distinguish residual from reactivated alkaline phosphatase. Alkaline phosphatase methodology is applicable to cheese. However, consideration must be given to the possibility of obtaining false-positive tests due to the possible presence of mold in the cheese. In the early 1940&#039;s, Scharer reported as follows: &quot;Our recent work has indicated that yeast and some molds (a culture of Oidium lactis and Penicillium notatum) which grown on cheese under certain conditions will produce appreciable amounts of phosphatase, but that if the mold growth is removed before the cheese sample is prepared for testing purpose, no difficulty or false positive is encountered.&quot; Thus, sampling of cheese is a very important consideration, i.e., one must be certain that no mold is evident. In addition, it is highly recommended that cheese be sampled before the addition of condiments such as peppers or spices as these materials may also be responsible for false positive tests. Ideally, cheese samples should be placed in clean containers, refrigerated, and tested within 36 hours in order to be certain that no development of microbial phosphatase has occurred. Finally, if cheese is not properly stored in the marketplace there is a possibility that microbial growth may occur which could result in false positive results for the alkaline phosphatase test. Thus, sampling of cheese for phosphatase analysis should be conducted before cheese enters marketing channels. ALKALINE PHOSPHATASE METHODOLOGY Dick H. Kleyn, Ph.D.,  Dept. of Food Science  Rutgers University  New Brunswick, NJ 08903 "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "Enzymes are organic catalysts which occur naturally in most raw foods. When milk is pasteurized most of the enzymes are inactivated or their activity is greatly diminished. The first reliable enzymatic test for determining efficiency of pasteurization was developed by Kay and Graham in England in 1933. It was based upon the inactivation of alkaline phosphatase." } } </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>Enzymes are organic catalysts which occur naturally in most raw foods. When milk is pasteurized most of the enzymes are inactivated or their activity is greatly diminished. The first reliable enzymatic test for determining efficiency of pasteurization was developed by Kay and Graham in England in 1933. It was based upon the inactivation of alkaline phosphatase.</p> <p>The phosphatase test is applied to dairy products to determine whether pasteurization was done properly and also to detect the possible addition of raw milk to pasteurized milk. The thermal resistance of alkaline phosphatase has been considered to be greater than that of any nonsporeforming pathogens that might be found in milk. However, the recent outbreaks of disease traced to Listeria monocytogenes in pasteurized milk lead one to begin to question this conclusion.</p> <p>Alkaline phosphatase is a monesterase that catalyzes the hydrolysis of monoesters.</p> <p>Studies have shown that the amount of alkaline phosphatase in raw milk is variable. The activity of phosphatase per unit of milk seems to be inversely correlated to milk yield, reaching a minimum in 1 or 2 weeks after calving and rising gradually to a maximum in about 25 weeks. Breed, feed of the cow, or fat content of the milk do not appear to influence phosphatase activity. Alkaline phosphatase is associated with the fat globule of milk, i.e., it is adsorbed to the fat globule membrane surface.</p> <p>Phosphatase tests currently described in Standard Methods for the Examination of Dairy Products are based on the principle that the alkaline phosphatase enzyme in raw milk liberates phenol from a disodium phenyl phosphate substrate (Scharer Method) or phenolphthalein from a phenolphthalein monophosphate substrate (Rutgers Method) when tests are conducted at suitable temperature and pH. The amount of phenol or phenolphthalein liberated from the substrate is proportional to the activity of the enzyme. Phenol is measured calorimetrically after its reaction with 2,6 dichloroquinone-chloroimide (CQC) to form indophenol. Phenolphthalein is detected by addition of sodium hydroxide.</p> <p>While the Scharer rapid method is relatively simple and quick, it must be recognized that it does possess some inherent weaknesses. There is a constant hazard of phenol contamination from reagents, glassware, and stoppers. Reagents are unstable as is the color formed by the reaction of phenol with the dye. Visual measurement of color is sometimes difficult, particularly with borderline cases; and emulsification frequently occurs during the extraction of the phenol with butanol.</p> <p>Phenolphthalein monophosphate is a very stable substrate which is easily hydrolyzed by alkaline phosphatase to yield free phenolphthalein. Our studies have revealed that the use of this substrate provides greater sensitivity than disodium phenyl phosphate. The high sensitivity is due to several factors, namely, the ease of color comparison, the high rate of hydrolysis, the elimination of variations because of specific color reaction and extraction, and the slight contribution of yellow color of milk fat to the pink color of phenolphthalein.</p> <p>It is necessary to run both positive and negative controls when conducting a phosphatase procedure. A negative control is prepared by heating a product to 90°C for 1 minute followed by rapid cooling. Any color developing when a test is run on the control indicates contamination of reagents or presence of interfering coloring materials or both. A positive control is run as a check on the proper functioning of reagents. It is conducted by adding 0.2 ml of fresh, raw mixed-herd milk to 100 ml of raw milk which has been heated at 90°C for 1 minute, followed by rapid cooling to room temperature. One should obtain a positive result on this test.</p> <p>Another control test should be run on samples which yield positive results in the initial analysis. This test is conducted in order to distinguish residual alkaline phosphatase from microbial alkaline phosphatase. Microbial phosphatases are considerably more heat resistant than is alkaline milk phosphatase. Therefore, it is possible to differentiate these enzymes by pasteurization of the sample in question and retesting. If there is no significant difference in the results of the test, one then concludes that the original positive result was due to microbial phosphatase.</p> <p>Reactivated phosphatase sometimes occurs in high fat dairy products which have been ultrapasteurized, such reactivation occurring quickly when samples are stored at non-refrigerated (70-90°F) temperatures. A test has been developed which permits one to distinguish residual from reactivated alkaline phosphatase.</p> <p>Alkaline phosphatase methodology is applicable to cheese. However, consideration must be given to the possibility of obtaining false-positive tests due to the possible presence of mold in the cheese. In the early 1940's, Scharer reported as follows: "Our recent work has indicated that yeast and some molds (a culture of Oidium lactis and Penicillium notatum) which grown on cheese under certain conditions will produce appreciable amounts of phosphatase, but that if the mold growth is removed before the cheese sample is prepared for testing purpose, no difficulty or false positive is encountered." Thus, sampling of cheese is a very important consideration, i.e., one must be certain that no mold is evident. In addition, it is highly recommended that cheese be sampled before the addition of condiments such as peppers or spices as these materials may also be responsible for false positive tests. Ideally, cheese samples should be placed in clean containers, refrigerated, and tested within 36 hours in order to be certain that no development of microbial phosphatase has occurred. Finally, if cheese is not properly stored in the marketplace there is a possibility that microbial growth may occur which could result in false positive results for the alkaline phosphatase test. Thus, sampling of cheese for phosphatase analysis should be conducted before cheese enters marketing channels.</p> <p>ALKALINE PHOSPHATASE METHODOLOGY<br /> Dick H. Kleyn, Ph.D., <br /> Dept. of Food Science <br /> Rutgers University <br /> New Brunswick, NJ 08903</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-food-sciences/dairy-chemistry" hreflang="en">Dairy Chemistry</a></div> </div> Mon, 19 Jun 2017 19:28:26 +0000 Anonymous 116 at https://drinc.ucdavis.edu Preparation of Casein from Skim Milk https://drinc.ucdavis.edu/dairy-food-sciences/preparation-casein-skim-milk <span class="field field--name-title field--type-string field--label-hidden">Preparation of Casein from Skim Milk</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 19, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-food-sciences/61/feed" addthis:title="" addthis:description="Background on Casein Casein is a mixture of phosphoproteins found in milk to the extent of about 3%. It contains all of the common amino acids an is high in the essential ones. Casein is often used as a dietary base for use in evaluation of vitamins, since it is easy to prepare casein as a pure protein.  Casein is usually prepared by acid precipitation. It exists in milk as the water soluble calcium salt of a phosphoprotein. Acid treatment removes the calcium cation, leaving a water insoluble phosphoprotein. Generally acetic acid is used because it is less harsh than hydrochloric acid. Most people extracting casein in the form of a school experiment do so with the solution cold. Such practice leads to the formation of casein with poor physical properties. Softness and rather incomplete separation of the casein are problems encountered. However, if the precipitation is performed warm, the casein separates as a single large colloid, with complete separation, leaving a yellow solution of whey behind. As a side note, whey primarily consists of milk-sugar, lactose. Decent casein precipitation is delicate. If too much acid is added, or if the acid is added too quickly, or if the acid is too strong, part of the casein will redissolve. Casein is amphoteric, that is, it forms salts with both acids and alkalines. Casein may be extracted from whole milk. Disadvantages are that whole milk contains a relatively large concentration of fat. This fat will be physically included in the casein curd as it separates. Thus, if at all possible, use skim milk. Procedure Prepare a solution of 7.0cc glacial acetic acid in 50.0cc water. This is the solution to be used for precipitation.  Place 600.0cc skim milk in a 1 liter beaker. Warm to 110° F. Dropwise and with stirring add the acetic acid solution prepared above. At a certain point a mass of casein will separate. Gather this from the beaker with a glass stirring rod. Do not add any more acid than necessary to obtain a good curd. A few minutes must be given between acid additions to allow for stabilization. Press the mass of casein between tissue to remove as much water as possible. Place the mass of casein in a food blender with 500cc water. Suspend the casein in the water by blending as much as possible. Separate the casein from the water with a filter and wash with isopropanol. If isopropanol is not available use ethanol or some low molecular weight alcohol. Use of ketones is not recommended due to increased polymerization. Let the casein powder air dry. Yield casein: 13.8g  "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "Background on Casein Casein is a mixture of phosphoproteins found in milk to the extent of about 3%. It contains all of the common amino acids an is high in the essential ones. Casein is often used as a dietary base for use in evaluation of vitamins, since it is easy to prepare casein as a pure protein.  Casein is usually prepared by acid precipitation. It exists in milk as the water soluble calcium salt of a phosphoprotein. Acid treatment removes the calcium cation, leaving a water insoluble phosphoprotein." } } </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"><h3>Background on Casein</h3> <p>Casein is a mixture of phosphoproteins found in milk to the extent of about 3%. It contains all of the common amino acids an is high in the essential ones. Casein is often used as a dietary base for use in evaluation of vitamins, since it is easy to prepare casein as a pure protein. <br /> Casein is usually prepared by acid precipitation. It exists in milk as the water soluble calcium salt of a phosphoprotein. Acid treatment removes the calcium cation, leaving a water insoluble phosphoprotein.</p> <p>Generally acetic acid is used because it is less harsh than hydrochloric acid. Most people extracting casein in the form of a school experiment do so with the solution cold. Such practice leads to the formation of casein with poor physical properties. Softness and rather incomplete separation of the casein are problems encountered.</p> <p>However, if the precipitation is performed warm, the casein separates as a single large colloid, with complete separation, leaving a yellow solution of whey behind. As a side note, whey primarily consists of milk-sugar, lactose.</p> <p>Decent casein precipitation is delicate. If too much acid is added, or if the acid is added too quickly, or if the acid is too strong, part of the casein will redissolve. Casein is amphoteric, that is, it forms salts with both acids and alkalines.</p> <p>Casein may be extracted from whole milk. Disadvantages are that whole milk contains a relatively large concentration of fat. This fat will be physically included in the casein curd as it separates. Thus, if at all possible, use skim milk.</p> <h3>Procedure</h3> <p>Prepare a solution of 7.0cc glacial acetic acid in 50.0cc water. This is the solution to be used for precipitation. <br /> Place 600.0cc skim milk in a 1 liter beaker. Warm to 110° F. Dropwise and with stirring add the acetic acid solution prepared above. At a certain point a mass of casein will separate. Gather this from the beaker with a glass stirring rod.</p> <p>Do not add any more acid than necessary to obtain a good curd. A few minutes must be given between acid additions to allow for stabilization.</p> <p>Press the mass of casein between tissue to remove as much water as possible. Place the mass of casein in a food blender with 500cc water. Suspend the casein in the water by blending as much as possible.</p> <p>Separate the casein from the water with a filter and wash with isopropanol. If isopropanol is not available use ethanol or some low molecular weight alcohol. Use of ketones is not recommended due to increased polymerization.</p> <p>Let the casein powder air dry.</p> <p>Yield casein: 13.8g </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-food-sciences/dairy-chemistry" hreflang="en">Dairy Chemistry</a></div> </div> Mon, 19 Jun 2017 19:27:30 +0000 Anonymous 111 at https://drinc.ucdavis.edu Procedures for Oxidized Milk Problems https://drinc.ucdavis.edu/dairy-food-sciences/procedures-oxidized-milk-problems <span class="field field--name-title field--type-string field--label-hidden">Procedures for Oxidized Milk Problems</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 19, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-food-sciences.rss" addthis:title="Dairy Food Sciences" addthis:description="I. Check entire pipeline system for any part that is not made of stainless steel, rubber, or plastic. Pipeline and pipeline fittings Receiver jar and probes Milk pump and attached valves, etc. Filter, strainers, etc. Bulk Tank - agitator paddle and rod, milk valve II. Wash up system Sink and sink drains and plugs Connecting lines from sink to pipeline No part that is not stainless, plastic, or rubber should be washed in sink To be safe in washing, use only rubber, plastic, or wood brushes III. Feed Determine if copper in any form is being added to any feed going to the milking herd, dry cows, or heifers 1. If copper is being added for molybdenum control the therapeutic dose is 1 gram of CuSO4 per mature cow per day during the trouble period this dosage can be cut to /2 gram/cow/day. If you need to double check the molybdenum problem run laboratory analysis on the herd&#039;s legume feed for Cu, Mo, and SO4-S (inorganic sulfates). (If the level of molybdenum is 50% or more than the Cu level and the level of SO4-S is over 2,000 PPM you have a molybdenum problem.) Regardless of the degree of molybdenosis, 1 gram of Cu SO4/cow /day is an adequate dose. No molybdenum problem, ask that no copper be added to the feed. A combination of most natural, California grown feeds contain adequate amounts of dietary copper. Trace mineral salt blocks are most likely to be all right IV. Alfalfa hay Since much of the hay grown in California contains a copper level of from 3 ppm to 15 ppm, it may be necessary to run levels of Copper on hay being fed while herd is oxidized. Data provided could be then checked against Copper levels in hay when the same herd is no longer oxidized. V. Determination of Copper contamination in pipeline Run copper levels on bulk tank milk from AM and PM milkings At next milking, sample bulk tank after the first 3 or 4 cows have been milked. Drain bulk tank, acid wash and rinse. Sample bulk tank again after end of milking. Cu levels run on both samples should give levels of Cu picked up by milk from pipeline system VI. Determination of Cu levels in pipeline Analyze hot and cold H2O for Cu Thoroughly wash sink with acid and rinse. Fill sink up with acid solution and take sample for copper analysis Flush pipeline system thoroughly (15 minutes) with acid solution Take sample of wash solution for Cu analysis Difference in copper levels would determine degree of Cu contamination in pipeline VII. If none of the above steps reduce oxidized flavor it will then be necessary to flavor the individual cows. Large herd, at least sample all 1st and 2nd lactation animals If a large percentage of the cows are found too be producing oxidized milk (intensity above 2) feed Vitamin E to the herd at 2,000 I.U./cow/day for 1 month. If flavor hasdisappeared by then, reduce level of E at rate of 400 I.U./cow/day each week.It may be possible or practical to feed E to only those cows found to be producing oxidized milk. It is also recommended that the Dairy Farm Advisor not only know and work with the processor personnel, but work within a specific company&#039;s policy procedures. "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "I. Check entire pipeline system for any part that is not made of stainless steel, rubber, or plastic. Pipeline and pipeline fittings Receiver jar and probes Milk pump and attached valves, etc. Filter, strainers, etc. Bulk Tank - agitator paddle and rod, milk valve II. Wash up system" } } </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>I. Check entire pipeline system for any part that is not made of stainless steel, rubber, or plastic.</p> <ul><li>Pipeline and pipeline fittings</li> <li>Receiver jar and probes</li> <li>Milk pump and attached valves, etc.</li> <li>Filter, strainers, etc.</li> <li>Bulk Tank - agitator paddle and rod, milk valve</li> </ul><p>II. Wash up system</p> <ul><li>Sink and sink drains and plugs</li> <li>Connecting lines from sink to pipeline</li> <li>No part that is not stainless, plastic, or rubber should be washed in sink</li> <li>To be safe in washing, use only rubber, plastic, or wood brushes</li> </ul><p>III. Feed</p> <ul><li>Determine if copper in any form is being added to any feed going to the milking herd, dry cows, or heifers 1. If copper is being added for molybdenum control the therapeutic dose is 1 gram of CuSO4 per mature cow per day during the trouble period this dosage can be cut to /2 gram/cow/day. If you need to double check the molybdenum problem run laboratory analysis on the herd's legume feed for Cu, Mo, and SO4-S (inorganic sulfates). (If the level of molybdenum is 50% or more than the Cu level and the level of SO4-S is over 2,000 PPM you have a molybdenum problem.) Regardless of the degree of molybdenosis, 1 gram of Cu SO4/cow /day is an adequate dose.</li> <li>No molybdenum problem, ask that no copper be added to the feed. A combination of most natural, California grown feeds contain adequate amounts of dietary copper.</li> <li>Trace mineral salt blocks are most likely to be all right</li> </ul><p>IV. Alfalfa hay</p> <ul><li>Since much of the hay grown in California contains a copper level of from 3 ppm to 15 ppm, it may be necessary to run levels of Copper on hay being fed while herd is oxidized. Data provided could be then checked against Copper levels in hay when the same herd is no longer oxidized.</li> </ul><p>V. Determination of Copper contamination in pipeline</p> <ul><li>Run copper levels on bulk tank milk from AM and PM milkings</li> <li>At next milking, sample bulk tank after the first 3 or 4 cows have been milked. Drain bulk tank, acid wash and rinse.</li> <li>Sample bulk tank again after end of milking. Cu levels run on both samples should give levels of Cu picked up by milk from pipeline system</li> </ul><p>VI. Determination of Cu levels in pipeline</p> <ul><li>Analyze hot and cold H2O for Cu</li> <li>Thoroughly wash sink with acid and rinse. Fill sink up with acid solution and take sample for copper analysis</li> <li>Flush pipeline system thoroughly (15 minutes) with acid solution</li> <li>Take sample of wash solution for Cu analysis</li> <li>Difference in copper levels would determine degree of Cu contamination in pipeline</li> </ul><p>VII. If none of the above steps reduce oxidized flavor it will then be necessary to flavor the individual cows.</p> <ul><li>Large herd, at least sample all 1st and 2nd lactation animals</li> <li>If a large percentage of the cows are found too be producing oxidized milk (intensity above 2) feed Vitamin E to the herd at 2,000 I.U./cow/day for 1 month. If flavor hasdisappeared by then, reduce level of E at rate of 400 I.U./cow/day each week.It may be possible or practical to feed E to only those cows found to be producing oxidized milk.</li> </ul><p>It is also recommended that the Dairy Farm Advisor not only know and work with the processor personnel, but work within a specific company's policy procedures.</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-food-sciences/dairy-chemistry" hreflang="en">Dairy Chemistry</a></div> </div> Mon, 19 Jun 2017 19:26:07 +0000 Anonymous 106 at https://drinc.ucdavis.edu Water Activity in Food https://drinc.ucdavis.edu/dairy-food-sciences/water-activity-food <span class="field field--name-title field--type-string field--label-hidden">Water Activity in Food</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 19, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-food-sciences.rss" addthis:title="Dairy Food Sciences" addthis:description="Water in food which is not bound to food molecules can support the growth of bacteria, yeasts and molds (fungi). The term water activity (aw) refers to this unbound water. The water activity of a food is not the same thing as its moisture content. Although moist foods are likely to have greater water activity than are dry foods, this is not always so; in fact a variety of foods may have exactly the same moisture content and yet have quite different water activities. The Typical Water Activity of Some Foodstuffs Type of Product Water Activity (AW) Fresh meat and fish .99 Bread .95 Aged Cheddar .85 Jams and jellies .8 Plum pudding .8 Dried Fruit .6 Biscuits .3 Milk powder .2 Instant coffee .2 Measuring Water Activity (AW) The water activity scale extends from 0 (bone dry) to 1.0 (pure water) but most foods have a water activity level in the range of 0.2 for very dry foods to 0.99 for moist fresh foods. Water activity is in practice usually measured as equilibrium relative humidity (ERH). The water activity (aw) represents the ratio of the water vapor pressure of the food to the water vapor pressure of pure water under the same conditions and it is expressed as a fraction. If we multiply this ratio by 100, we obtain the equilibrium relative humidity (ERH) that the foodstuff would produce if enclosed with air in a sealed container at constant temperature. Thus a food with a water activity (aw) of 0.7 would produce an ERH of 70%. Predicting Food Spoilage Water activity (aw) has its most useful application in predicting the growth of bacteria, yeasts and molds. For a food to have a useful shelf life without relying on refrigerated storage, it is necessary to control either its acidity level (pH) or the level of water activity (aw) or a suitable combination of the two. This can effectively increase the product&#039;s stability and make it possible to predict its shelf life under known ambient storage conditions. Food can be made safe to store by lowering the water activity to a point that will not allow dangerous pathogens such as Clostridium botulinum and Staphylococcus aureus to grow in it. The diagram below illustrates the water activity (aw) levels which can support the growth of particular groups of bacteria, yeasts and molds. For example we can see that food with a water activity below 0.6 will not support the growth of osmophilic yeasts. We also know that Clostridium botulinum, the most dangerous food poisoning bacterium, is unable to grow at an aw of .93 and below. The risk of food poisoning must be considered in low acid foods (pH &gt; 4.5) with a water activity greater than 0.86 aw. Staphylococcus aureus, a common food poisoning organism, can grow down to this relatively low water activity level. Foods which may support the growth of this bacterium include cheese and fermented sausages stored above correct refrigeration temperatures. Semi-Moist Foods For foods with a relatively high water activity correct refrigeration is always necessary. These include most fresh foods and many processed foods such as soft cheeses and cured meats. However many foods can be successfully stored at room temperature by proper control of their water activity (aw). These foods can be described as semi-moist and include fruit cakes, puddings and sweet sauces such as chocolate and caramel. When these foods spoil, it is usually the result of surface mold growth. Most molds cease to grow at a water activity level below about 0.8, but since some molds will grow slowly at this aw, it is usually recommended that products of this type do not have an aw greater than 0.75. While this will not ensure complete freedom from microbial spoilage, those few yeasts and molds which do grow at lower water activities need only to be considered when special shelf life conditions must be met For example a commercial shelf life over twelve months might be required for confectionery; in these circumstances an aw below 0.6 would be required. "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "Water in food which is not bound to food molecules can support the growth of bacteria, yeasts and molds (fungi). The term water activity (aw) refers to this unbound water. The water activity of a food is not the same thing as its moisture content. Although moist foods are likely to have greater water activity than are dry foods, this is not always so; in fact a variety of foods may have exactly the same moisture content and yet have quite different water activities." } } </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>Water in food which is not bound to food molecules can support the growth of bacteria, yeasts and molds (fungi). The term water activity (aw) refers to this unbound water.</p> <p>The water activity of a food is not the same thing as its moisture content. Although moist foods are likely to have greater water activity than are dry foods, this is not always so; in fact a variety of foods may have exactly the same moisture content and yet have quite different water activities.</p> <div>The Typical Water Activity of Some Foodstuffs <table><tbody><tr><td> <div><strong>Type of Product</strong></div> </td> <td> <div><strong>Water Activity (AW)</strong></div> </td> </tr><tr><td>Fresh meat and fish</td> <td> <div>.99</div> </td> </tr><tr><td>Bread</td> <td> <div>.95</div> </td> </tr><tr><td>Aged Cheddar</td> <td> <div>.85</div> </td> </tr><tr><td>Jams and jellies</td> <td> <div>.8</div> </td> </tr><tr><td>Plum pudding</td> <td> <div>.8</div> </td> </tr><tr><td>Dried Fruit</td> <td> <div>.6</div> </td> </tr><tr><td>Biscuits</td> <td> <div>.3</div> </td> </tr><tr><td>Milk powder</td> <td> <div>.2</div> </td> </tr><tr><td>Instant coffee</td> <td> <div>.2</div> </td> </tr></tbody></table></div> <div> <h3>Measuring Water Activity (AW)</h3> <p>The water activity scale extends from 0 (bone dry) to 1.0 (pure water) but most foods have a water activity level in the range of 0.2 for very dry foods to 0.99 for moist fresh foods. Water activity is in practice usually measured as equilibrium relative humidity (ERH).</p> </div> <p>The water activity (aw) represents the ratio of the water vapor pressure of the food to the water vapor pressure of pure water under the same conditions and it is expressed as a fraction. If we multiply this ratio by 100, we obtain the equilibrium relative humidity (ERH) that the foodstuff would produce if enclosed with air in a sealed container at constant temperature. Thus a food with a water activity (aw) of 0.7 would produce an ERH of 70%.</p> <h3>Predicting Food Spoilage</h3> <p>Water activity (aw) has its most useful application in predicting the growth of bacteria, yeasts and molds. For a food to have a useful shelf life without relying on refrigerated storage, it is necessary to control either its acidity level (pH) or the level of water activity (aw) or a suitable combination of the two. This can effectively increase the product's stability and make it possible to predict its shelf life under known ambient storage conditions. Food can be made safe to store by lowering the water activity to a point that will not allow dangerous pathogens such as Clostridium botulinum and Staphylococcus aureus to grow in it. The diagram below illustrates the water activity (aw) levels which can support the growth of particular groups of bacteria, yeasts and molds. For example we can see that food with a water activity below 0.6 will not support the growth of osmophilic yeasts. We also know that Clostridium botulinum, the most dangerous food poisoning bacterium, is unable to grow at an aw of .93 and below.</p> <p>The risk of food poisoning must be considered in low acid foods (pH &gt; 4.5) with a water activity greater than 0.86 aw. Staphylococcus aureus, a common food poisoning organism, can grow down to this relatively low water activity level. Foods which may support the growth of this bacterium include cheese and fermented sausages stored above correct refrigeration temperatures.</p> <h3>Semi-Moist Foods</h3> <p>For foods with a relatively high water activity correct refrigeration is always necessary. These include most fresh foods and many processed foods such as soft cheeses and cured meats. However many foods can be successfully stored at room temperature by proper control of their water activity (aw). These foods can be described as semi-moist and include fruit cakes, puddings and sweet sauces such as chocolate and caramel.</p> <p>When these foods spoil, it is usually the result of surface mold growth. Most molds cease to grow at a water activity level below about 0.8, but since some molds will grow slowly at this aw, it is usually recommended that products of this type do not have an aw greater than 0.75.</p> <p>While this will not ensure complete freedom from microbial spoilage, those few yeasts and molds which do grow at lower water activities need only to be considered when special shelf life conditions must be met For example a commercial shelf life over twelve months might be required for confectionery; in these circumstances an aw below 0.6 would be required.</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-food-sciences/dairy-chemistry" hreflang="en">Dairy Chemistry</a></div> </div> Mon, 19 Jun 2017 19:24:29 +0000 Anonymous 101 at https://drinc.ucdavis.edu A Summary of Titratable Acidity https://drinc.ucdavis.edu/dairy-food-sciences/summary-titratable-acidity <span class="field field--name-title field--type-string field--label-hidden">A Summary of Titratable Acidity</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 19, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-food-sciences.rss" addthis:title="Dairy Food Sciences" addthis:description="There are two fundamentally different methods of expressing acidity: (a) titratable acidity expressed as percent lactic acid, and (b) hydrogen ion concentration or pH. The former measures the total acidity but does not measure the strength of the acids. The pH indicates the strength of the acid condition. The true neutral point is at pH 7.0; pH values below 7.0 indicate an acid reaction; pH values above 7.O indicate an alkaline reaction. One pH unit means a tenfold difference in strength; for example, a pH 5.5 indicates an acidity that is ten times as great as pH 6.5. It is the pH that determines such processes as curdling of milk the action of enzymes, the growth of bacteria, the color of indicators, taste, etc. Today pH is easy to measure. The customary practice of using a 9 cc. sample in titrating dairy products involves a weight discrepancy. Since the acidity test is used for comparative purposes, this discrepancy is not serious. However, when we compare different products (i.e.. milk and cream, milk and condensed milk), this discrepancy must be remembered. When titrating dairy products to the pink color of the phenolphthalein endpoint, we are titrating to about a pH 8.3 or 8.4, which is quite appreciably on the alkaline side of the true neutral point. On the other hand titrating to A pH of 7.0 will result in a different % acidity. Most &quot;normal&quot; acidities reported in the early literature were determined with the phenolphthalein indicator. Thus, the true acidity is reported higher than it actually is. If we add distilled water to the measured sample of milk, a lower titratable acidity value is obtained. This is due to the fact that there will be less precipitation of tri-calcium phosphate. The acidity of milk from individual cows ranges from 0.10 to 0.26 %. Herd milk varies less in acidity because of commingling,, but occasionally herds are found where the acidity of the fresh milk is 0.18 % and as high as 0.23 %. The acidity of fresh milk is due to phosphates, casein and whey proteins, citrates and carbon dioxide. The acidity of milk may change during the lactation period but no definite trend can be stated except that (a) the acidity of colostrum is high, and (b) the milk towards the very end of the lactation period frequently has a lower acidity.  It has been impossible to increase the acidity of milk by feeding silage or even by feeding such inorganic acids such as inorganic as sulphuric acid or phosphoric acid. Mastitis, even in mild or sub-clinical form, causes the acidity of the milk to be lower. In rare cases mastitis causes a high acidity in the milk. The acids produced by bacteria growing in milk are mainly lactic and acetic acids. The number of bacteria must increase to several millions per mL before there is a measurable increase in acidity. The acidity test must be used with considerable discretion, if used at all, for grading raw milk at the plant intake, because (a) fresh milk varies widely in acidity, and (b) millions of bacteria are required to produce the first rise in acidity. This bacterial growth can only occur if the farm milk was held un- refrigerated at 55 F or more. for several hours. If this were the case the required recording thermometer would show a refrigeration problem. This &quot;high acidity&quot; milk would also have show a SPC in excess of 500,000 per mL. The expected acidity of cream is frequently calculated from the acidity of the milk and the fat content of the cream. This calculation does not hold unless the acidity of the cream is determined by measuring g cc. of cream, adding 9 cc. of water, and then titrating as usual. Failure to recognize this fact has led to unjustifiable neutralization of sweet cream. If the acidity of condensed milk products is determined for the purpose of forming an opinion as to the raw material used, then the sample should be measured as in the case of milk or skim milk. Enough distilled water should be added to the measured sample to dilute the condensed product to the original concentration of the milk. The acidity of ice cream mixes is higher than the acidity of milk in the same proportion that the serum solids content of the mix is higher than that of milk. "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "There are two fundamentally different methods of expressing acidity: (a) titratable acidity expressed as percent lactic acid, and (b) hydrogen ion concentration or pH. The former measures the total acidity but does not measure the strength of the acids. The pH indicates the strength of the acid condition. The true neutral point is at pH 7.0; pH values below 7.0 indicate an acid reaction; pH values above 7.O indicate an alkaline reaction." } } </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"><ol><li>There are two fundamentally different methods of expressing acidity: (a) titratable acidity expressed as percent lactic acid, and (b) hydrogen ion concentration or pH. The former measures the total acidity but does not measure the strength of the acids. The pH indicates the strength of the acid condition.</li> <li>The true neutral point is at pH 7.0; pH values below 7.0 indicate an acid reaction; pH values above 7.O indicate an alkaline reaction. One pH unit means a tenfold difference in strength; for example, a pH 5.5 indicates an acidity that is ten times as great as pH 6.5.</li> <li>It is the pH that determines such processes as curdling of milk the action of enzymes, the growth of bacteria, the color of indicators, taste, etc. Today pH is easy to measure.</li> <li>The customary practice of using a 9 cc. sample in titrating dairy products involves a weight discrepancy. Since the acidity test is used for comparative purposes, this discrepancy is not serious. However, when we compare different products (i.e.. milk and cream, milk and condensed milk), this discrepancy must be remembered.</li> <li>When titrating dairy products to the pink color of the phenolphthalein endpoint, we are titrating to about a pH 8.3 or 8.4, which is quite appreciably on the alkaline side of the true neutral point. On the other hand titrating to A pH of 7.0 will result in a different % acidity. Most "normal" acidities reported in the early literature were determined with the phenolphthalein indicator. Thus, the true acidity is reported higher than it actually is.</li> <li>If we add distilled water to the measured sample of milk, a lower titratable acidity value is obtained. This is due to the fact that there will be less precipitation of tri-calcium phosphate.</li> <li>The acidity of milk from individual cows ranges from 0.10 to 0.26 %. Herd milk varies less in acidity because of commingling,, but occasionally herds are found where the acidity of the fresh milk is 0.18 % and as high as 0.23 %.</li> <li>The acidity of fresh milk is due to phosphates, casein and whey proteins, citrates and carbon dioxide.</li> <li>The acidity of milk may change during the lactation period but no definite trend can be stated except that (a) the acidity of colostrum is high, and (b) the milk towards the very end of the lactation period frequently has a lower acidity.</li> <li> It has been impossible to increase the acidity of milk by feeding silage or even by feeding such inorganic acids such as inorganic as sulphuric acid or phosphoric acid.</li> <li>Mastitis, even in mild or sub-clinical form, causes the acidity of the milk to be lower. In rare cases mastitis causes a high acidity in the milk.</li> <li>The acids produced by bacteria growing in milk are mainly lactic and acetic acids.</li> <li>The number of bacteria must increase to several millions per mL before there is a measurable increase in acidity.</li> <li>The acidity test must be used with considerable discretion, if used at all, for grading raw milk at the plant intake, because (a) fresh milk varies widely in acidity, and (b) millions of bacteria are required to produce the first rise in acidity. This bacterial growth can only occur if the farm milk was held un- refrigerated at 55 F or more. for several hours. If this were the case the required recording thermometer would show a refrigeration problem. This "high acidity" milk would also have show a SPC in excess of 500,000 per mL.</li> <li>The expected acidity of cream is frequently calculated from the acidity of the milk and the fat content of the cream. This calculation does not hold unless the acidity of the cream is determined by measuring g cc. of cream, adding 9 cc. of water, and then titrating as usual. Failure to recognize this fact has led to unjustifiable neutralization of sweet cream.</li> <li>If the acidity of condensed milk products is determined for the purpose of forming an opinion as to the raw material used, then the sample should be measured as in the case of milk or skim milk. Enough distilled water should be added to the measured sample to dilute the condensed product to the original concentration of the milk.</li> <li>The acidity of ice cream mixes is higher than the acidity of milk in the same proportion that the serum solids content of the mix is higher than that of milk.</li> </ol> </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-food-sciences/dairy-chemistry" hreflang="en">Dairy Chemistry</a></div> </div> Mon, 19 Jun 2017 19:23:14 +0000 Anonymous 96 at https://drinc.ucdavis.edu Trans Fatty Acids - Information on fat, including definintions of key terms regarding fat. https://drinc.ucdavis.edu/dairy-food-sciences/trans-fatty-acids-information-fat-including-definintions-key-terms-regarding <span class="field field--name-title field--type-string field--label-hidden">Trans Fatty Acids - Information on fat, including definintions of key terms regarding fat.</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 19, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-food-sciences/61/feed" addthis:title="" addthis:description="Energy is stored in the body mostly in the form of fat. Fat is needed in the diet to supply essential fatty acids, substances required for growth but not produced by the human body. Dietary fat is needed to carry the fat-soluble vitamins A, D, E, and K and to aid in their absorption from the intestine. Fats are a group of chemical compounds that contain fatty acids. All fatty acids are molecules composed mostly of carbon and hydrogen atoms. The carbon atoms of a fatty acid are hooked together like a string of beads; a hydrogen atom can hook to the top of each carbon and another can hook to the bottom. There are three main types of fatty acids: saturated, monounsaturated and polyunsaturated. A saturated fatty acid has the maximum possible number of hydrogen atoms attached to every carbon atom. Therefore, it is said to be &quot;saturated&quot; with hydrogen atoms. Saturated fatty acids are long straight molecules that line up beside each other easily. They &quot;pack&quot; together and form solid fats at room temperature. Some fatty acids are missing one pair of hydrogen atoms in the middle of the molecule; one hydrogen is missing from each of two adjacent carbon atoms. This gap is called an &quot;unsaturation&quot; and the fatty acid is said to be &quot;monounsaturated&quot; because it has one gap. The gap at the point of unsaturation forms a &quot;kink&quot; in the molecule so it won&#039;t line up and pack with other molecules. This causes the fat to be liquid at room temperature. Fatty acids that are missing more than one pair of hydrogen atoms are called &quot;polyunsaturated.&quot; Polyunsaturated fatty acids are so kinked that they hardly pack at all making them remain liquid even at refrigeration temperature. Saturated fats contain predominately saturated fatty acids and are found primarily in foods of animal origin. Monounsaturated and polyunsaturated fats which contain monounsaturated and polyunsaturated fatty acids and are found primarily in foods of plant origin and in some seafoods. Polyunsaturated fatty acids are of two kinds, omega-3 or omega-6. Scientists tell them apart by where in the &quot;unsaturations,&quot; or missing hydrogen atoms, occur if you count the number of carbons from the end of the chain. Recently a new term has been added to the fat lexicon: trans fatty acids. These are by-products of partial hydrogenation, a process in which some of the missing hydrogen atoms are put back into polyunsaturated fats. Until the early 1900s, if you wanted a solid fat for your pie crust, you had to choose between lard, butter, and beef tallow. At the turn of the century a process was discovered that uses heat in the presence of hydrogen and certain metal catalysts to convert natural liquid vegetable oils into solid fats. This change in physical state occurs because some unsaturated bonds become saturated (fully hydrogenated) and others are converted from their natural &quot;cis&quot; arrangement to the &quot;trans&quot; position, creating straight molecules that pack together more solidly. &quot;Partially hydrogenated vegetable oils,&quot; such as vegetable shortening and margarine, are solid at room temperature. In 1911, Procter and Gamble introduced Crisco, a shortening made by hydrogenating a liquid oil (cottonseed). Trans fatty acids form when hydrogen is added to liquid oils. &quot;Trans&quot; and &quot;Cis&quot; refer to the physical structure of the fat. &quot;Cis&quot; means that hydrogen atoms are on the same side of the unsaturated carbon atoms in a fatty acid. &quot;Trans&quot; means across; when hydrogen is added to unsaturated fatty acids, some of the unsaturated bonds become saturated but some of the unsaturated bonds &quot;rearrange&quot; so the hydrogen atoms are on the opposite side of the carbon atoms. Trans fats are &quot;stiffer&quot; than cis fats because the fatty acids are straighter so they pack together to form solid material necessary for making foods like pastry. In the mid 1980s, the food industry responded to recommendations from health authorities and interest from consumers to reduce the amount of animal fats and tropical oils in the food supply. Both are high in saturated fatty acids which is linked to a number of public health risks. The best available alternative in many cases was to reformulate products by substituting partially hydrogenated vegetable oils for the highly saturated fats. Because butter is rich in both saturated fat and cholesterol, it is potentially a highly atherogenic food. Another concern is that trans fatty acids have been linked to increased risk of coronary heart disease (CHD). The effects of hydrogenated dietary fats on raising fats in the blood were initially investigated in the 1960s. Study results in the 1970s did not show clear relationships of trans fatty acids to increased heart disease risk. Since 1990, several studies in women and men have shown trans fatty acids to increase total blood cholesterol and LDL (low density lipoprotein) while decreasing HDL (high density lipoprotein) cholesterol, the protective form of blood cholesterol. The Nurses&#039; Health Study, a prospective trial involving more than 85,000 women, showed a positive association of trans fatty acids with coronary heart disease. By analyzing individual foods, this study suggested that trans fatty acids formed during the partial hydrogenation of vegetable oils used in margarine, cookies, cakes, and white bread accounted for all of the increased risk of CHD. There are naturally occurring trans fatty acids in animal fat, but these foods did not have the same association to risk of CHD in this study. An increased risk of heart attack was evident only among women consuming more than .5 pats of margarine per day. The risk remained significant after adjusting for other risk factors for CHD, including cigarette smoking, body mass index, hypertension, alcohol intake, dietary fat intake, and family history of early heart attack. However, the study did not address the apparent inverse relationship between trans fatty acid intake and the intake of carotene, dietary fiber, saturated fat, monounsaturated fat, vitamin/mineral supplementation and the amount of daily exercise. The findings are thought provoking, but conclusions cannot be drawn based on this study alone; dietary patterns and lifestyles are what may be related to increased risk of CHD. Most margarine is made from vegetable fat and provides no dietary cholesterol. The more liquid the margarine (i.e. tub and liquid forms) the less hydrogenated it is and the less trans fatty acid it contains. Therefore, margarine is still a preferable substitute for butter, and soft margarines are better than hard ones. The American Heart Association recommends that consumers shop for margarine with no more than two grams of saturated fat per tablespoon. They should choose soft margarine over stick forms to limit their intake of cholesterol-raising trans fatty acids. Partially hydrogenated vegetable oil is found in solid vegetable fats, such as shortening and margarine, and foods made with these types of fats. Trans fatty acids are naturally occurring in some animal fats. Trans fatty acids from all sources are estimated to account for approximately 5 to 8 percent of calories in the American diet. The typical American diet currently provides about 12 percent of calories from saturated fat and 34 percent of calories from total dietary fat. The American Dietetic Association and the American Heart Association are NOT recommending that everyone substitute butter for margarine due to these studies. The total amount of fat in the diet is still more important than the contribution trans fatty acids makes to heart disease risk. Sara C. Parks, President of the American Dietetic Association, responded to the controversy over trans fatty acids with the following statements: &quot;The body of available scientific evidence on trans fatty acids is inconclusive. What&#039;s known, after extensive scientific research, is that a diet high in fat increases the risk for a number of diseases. By reducing their fat intake to the recommended level of no more than 30 percent (of calories), Americans can reduce the health risks posed by all types of fat.&quot; The American Heart Association&#039;s Nutrition Committee continues to monitor research in this area. The committee advises that healthy Americans over the age of two limit their total fat intake to less than 30 percent of total calories. If people limit their daily intake of fats and oils to 5-8 teaspoons, they are not likely to get an excess of trans fatty acids. Trans fatty acids are not listed specifically on the Nutrition Facts Label. There is one regulation for a descriptive word that takes trans fatty acids into account; to make a &quot;saturated fat free&quot; claim, the product must contain less than 0.5 grams of trans fatty acids per serving. Information on the trans fatty acid content of foods is limited due to a lack of USDA composition data and changes in food manufacturing processes. Fat Words  Here are brief definitions of the key terms important to an understanding of the role of fat in the diet Cholesterol A chemical compound manufactured in the body. It is used to build cell membranes and brain and nerve tissues. Cholesterol also helps the body make steroid hormones and bile acids. Dietary cholesterol Cholesterol found in animal products that are part of the human diet. Egg yolks, liver, meat, some shell- fish, and whole-milk dairy products are all sources of dietary cholesterol. Fatty acid A molecule composed mostly of carbon and hydrogen atoms. Fatty acids are the building blocks of fats. Fat A chemical compound containing one or more fatty acids. Fat is one of the three main constituents of food (the others are protein and carbohydrate). It is also the principal form in which energy is stored in the body. Hydrogenated fat: A fat that has been chemically altered by the addition of hydrogen atoms (see trans fatty acid). Vegetable oil and margarine are hydrogenated fats. Lipid A chemical compound characterized by the fact that it is insoluble in water. Both fat and cholesterol are members of the lipid family. Lipoprotein A chemical compound made of fat and protein. Lipoproteins that have more fat than protein are called low- density lipoproteins (LDLs). Lipoproteins that have more protein than fat are called high-density lipoproteins (HDLs). Lipoproteins are found in the blood, where their main function is to carry cholesterol. Monounsaturated fatty acid A fatty acid that is missing one pair of hydrogen atoms in the middle of the molecule. The gap is called an &quot;unsaturation.&quot; Monounsaturated fatty acids are found mostly in plant and sea foods. Monounsaturated fat: A fat made of monounsaturated fatty acids. Olive oil and canola oil are monounsaturated fats. Monounsaturated fats tend to lower levels of LDL-cholesterol in the blood. Polyunsaturated fatty acid A fatty acid that is missing more than one pair of hydrogen atoms. Polyunsaturated fatty acids are mostly found in plant and sea foods. Polyunsaturated fat: A fat made of polyunsaturated fatty acids. Safflower oil and corn oil are polyunsaturated fats. Polyunsaturated fats tend to lower levels of both HDL-cholesterol and LDL-cholesterol in the blood. Saturated fatty acid A fatty acid that has the maximum possible number of hydrogen atoms attached to every carbon atom. It is said to be &quot;saturated&quot; with hydrogen atoms. Saturated fatty acids are mostly found in animal products such as meat and whole milk. Saturated fat A fat made of saturated fatty acids. Butter and lard are saturated fats. Saturated fats tend to raise levels of LDL-cholesterol (&quot;bad&quot; cholesterol) in the blood. Elevated levels of LDL-cholesterol are associated with heart disease. Trans fatty acid A polyunsaturated fatty acid in which some of the missing hydrogen atoms have been put back in a chemical process called hydrogenation. Trans fatty acids are the building blocks of hydrogenated fats. "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "Energy is stored in the body mostly in the form of fat. Fat is needed in the diet to supply essential fatty acids, substances required for growth but not produced by the human body. Dietary fat is needed to carry the fat-soluble vitamins A, D, E, and K and to aid in their absorption from the intestine. Fats are a group of chemical compounds that contain fatty acids. All fatty acids are molecules composed mostly of carbon and hydrogen atoms." } } </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>Energy is stored in the body mostly in the form of fat. Fat is needed in the diet to supply essential fatty acids, substances required for growth but not produced by the human body. Dietary fat is needed to carry the fat-soluble vitamins A, D, E, and K and to aid in their absorption from the intestine. Fats are a group of chemical compounds that contain fatty acids. All fatty acids are molecules composed mostly of carbon and hydrogen atoms. The carbon atoms of a fatty acid are hooked together like a string of beads; a hydrogen atom can hook to the top of each carbon and another can hook to the bottom.</p> <p>There are three main types of fatty acids: saturated, monounsaturated and polyunsaturated. A saturated fatty acid has the maximum possible number of hydrogen atoms attached to every carbon atom. Therefore, it is said to be "saturated" with hydrogen atoms. Saturated fatty acids are long straight molecules that line up beside each other easily. They "pack" together and form solid fats at room temperature. Some fatty acids are missing one pair of hydrogen atoms in the middle of the molecule; one hydrogen is missing from each of two adjacent carbon atoms. This gap is called an "unsaturation" and the fatty acid is said to be "monounsaturated" because it has one gap. The gap at the point of unsaturation forms a "kink" in the molecule so it won't line up and pack with other molecules. This causes the fat to be liquid at room temperature. Fatty acids that are missing more than one pair of hydrogen atoms are called "polyunsaturated."</p> <p>Polyunsaturated fatty acids are so kinked that they hardly pack at all making them remain liquid even at refrigeration temperature. Saturated fats contain predominately saturated fatty acids and are found primarily in foods of animal origin. Monounsaturated and polyunsaturated fats which contain monounsaturated and polyunsaturated fatty acids and are found primarily in foods of plant origin and in some seafoods.</p> <p>Polyunsaturated fatty acids are of two kinds, omega-3 or omega-6. Scientists tell them apart by where in the "unsaturations," or missing hydrogen atoms, occur if you count the number of carbons from the end of the chain. Recently a new term has been added to the fat lexicon: trans fatty acids.</p> <p>These are by-products of partial hydrogenation, a process in which some of the missing hydrogen atoms are put back into polyunsaturated fats. Until the early 1900s, if you wanted a solid fat for your pie crust, you had to choose between lard, butter, and beef tallow. At the turn of the century a process was discovered that uses heat in the presence of hydrogen and certain metal catalysts to convert natural liquid vegetable oils into solid fats. This change in physical state occurs because some unsaturated bonds become saturated (fully hydrogenated) and others are converted from their natural "cis" arrangement to the "trans" position, creating straight molecules that pack together more solidly.</p> <p>"Partially hydrogenated vegetable oils," such as vegetable shortening and margarine, are solid at room temperature. In 1911, Procter and Gamble introduced Crisco, a shortening made by hydrogenating a liquid oil (cottonseed). Trans fatty acids form when hydrogen is added to liquid oils. "Trans" and "Cis" refer to the physical structure of the fat. "Cis" means that hydrogen atoms are on the same side of the unsaturated carbon atoms in a fatty acid. "Trans" means across; when hydrogen is added to unsaturated fatty acids, some of the unsaturated bonds become saturated but some of the unsaturated bonds "rearrange" so the hydrogen atoms are on the opposite side of the carbon atoms.</p> <p>Trans fats are "stiffer" than cis fats because the fatty acids are straighter so they pack together to form solid material necessary for making foods like pastry. In the mid 1980s, the food industry responded to recommendations from health authorities and interest from consumers to reduce the amount of animal fats and tropical oils in the food supply. Both are high in saturated fatty acids which is linked to a number of public health risks. The best available alternative in many cases was to reformulate products by substituting partially hydrogenated vegetable oils for the highly saturated fats.</p> <p>Because butter is rich in both saturated fat and cholesterol, it is potentially a highly atherogenic food. Another concern is that trans fatty acids have been linked to increased risk of coronary heart disease (CHD). The effects of hydrogenated dietary fats on raising fats in the blood were initially investigated in the 1960s.</p> <p>Study results in the 1970s did not show clear relationships of trans fatty acids to increased heart disease risk. Since 1990, several studies in women and men have shown trans fatty acids to increase total blood cholesterol and LDL (low density lipoprotein) while decreasing HDL (high density lipoprotein) cholesterol, the protective form of blood cholesterol. The Nurses' Health Study, a prospective trial involving more than 85,000 women, showed a positive association of trans fatty acids with coronary heart disease. By analyzing individual foods, this study suggested that trans fatty acids formed during the partial hydrogenation of vegetable oils used in margarine, cookies, cakes, and white bread accounted for all of the increased risk of CHD.</p> <p>There are naturally occurring trans fatty acids in animal fat, but these foods did not have the same association to risk of CHD in this study. An increased risk of heart attack was evident only among women consuming more than .5 pats of margarine per day. The risk remained significant after adjusting for other risk factors for CHD, including cigarette smoking, body mass index, hypertension, alcohol intake, dietary fat intake, and family history of early heart attack. However, the study did not address the apparent inverse relationship between trans fatty acid intake and the intake of carotene, dietary fiber, saturated fat, monounsaturated fat, vitamin/mineral supplementation and the amount of daily exercise.</p> <p>The findings are thought provoking, but conclusions cannot be drawn based on this study alone; dietary patterns and lifestyles are what may be related to increased risk of CHD. Most margarine is made from vegetable fat and provides no dietary cholesterol. The more liquid the margarine (i.e. tub and liquid forms) the less hydrogenated it is and the less trans fatty acid it contains. Therefore, margarine is still a preferable substitute for butter, and soft margarines are better than hard ones.</p> <p>The American Heart Association recommends that consumers shop for margarine with no more than two grams of saturated fat per tablespoon. They should choose soft margarine over stick forms to limit their intake of cholesterol-raising trans fatty acids. Partially hydrogenated vegetable oil is found in solid vegetable fats, such as shortening and margarine, and foods made with these types of fats. Trans fatty acids are naturally occurring in some animal fats. Trans fatty acids from all sources are estimated to account for approximately 5 to 8 percent of calories in the American diet.</p> <p>The typical American diet currently provides about 12 percent of calories from saturated fat and 34 percent of calories from total dietary fat. The American Dietetic Association and the American Heart Association are NOT recommending that everyone substitute butter for margarine due to these studies. The total amount of fat in the diet is still more important than the contribution trans fatty acids makes to heart disease risk. Sara C. Parks, President of the American Dietetic Association, responded to the controversy over trans fatty acids with the following statements: "The body of available scientific evidence on trans fatty acids is inconclusive. What's known, after extensive scientific research, is that a diet high in fat increases the risk for a number of diseases. By reducing their fat intake to the recommended level of no more than 30 percent (of calories), Americans can reduce the health risks posed by all types of fat."</p> <p>The American Heart Association's Nutrition Committee continues to monitor research in this area. The committee advises that healthy Americans over the age of two limit their total fat intake to less than 30 percent of total calories. If people limit their daily intake of fats and oils to 5-8 teaspoons, they are not likely to get an excess of trans fatty acids. Trans fatty acids are not listed specifically on the Nutrition Facts Label. There is one regulation for a descriptive word that takes trans fatty acids into account; to make a "saturated fat free" claim, the product must contain less than 0.5 grams of trans fatty acids per serving. Information on the trans fatty acid content of foods is limited due to a lack of USDA composition data and changes in food manufacturing processes.</p> <h3>Fat Words </h3> <p>Here are brief definitions of the key terms important to an understanding of the role of fat in the diet</p> <ul><li><strong>Cholesterol</strong><br /> A chemical compound manufactured in the body. It is used to build cell membranes and brain and nerve tissues. Cholesterol also helps the body make steroid hormones and bile acids.</li> <li><strong>Dietary cholesterol</strong><br /> Cholesterol found in animal products that are part of the human diet. Egg yolks, liver, meat, some shell- fish, and whole-milk dairy products are all sources of dietary cholesterol.</li> <li><strong>Fatty acid</strong><br /> A molecule composed mostly of carbon and hydrogen atoms. Fatty acids are the building blocks of fats.</li> <li><strong>Fat</strong><br /> A chemical compound containing one or more fatty acids. Fat is one of the three main constituents of food (the others are protein and carbohydrate). It is also the principal form in which energy is stored in the body. Hydrogenated fat: A fat that has been chemically altered by the addition of hydrogen atoms (see trans fatty acid). Vegetable oil and margarine are hydrogenated fats.</li> <li><strong>Lipid</strong><br /> A chemical compound characterized by the fact that it is insoluble in water. Both fat and cholesterol are members of the lipid family.</li> <li><strong>Lipoprotein</strong><br /> A chemical compound made of fat and protein. Lipoproteins that have more fat than protein are called low- density lipoproteins (LDLs). Lipoproteins that have more protein than fat are called high-density lipoproteins (HDLs). Lipoproteins are found in the blood, where their main function is to carry cholesterol.</li> <li><strong>Monounsaturated fatty acid</strong><br /> A fatty acid that is missing one pair of hydrogen atoms in the middle of the molecule. The gap is called an "unsaturation." Monounsaturated fatty acids are found mostly in plant and sea foods. Monounsaturated fat: A fat made of monounsaturated fatty acids. Olive oil and canola oil are monounsaturated fats. Monounsaturated fats tend to lower levels of LDL-cholesterol in the blood.</li> <li><strong>Polyunsaturated fatty acid</strong><br /> A fatty acid that is missing more than one pair of hydrogen atoms. Polyunsaturated fatty acids are mostly found in plant and sea foods. Polyunsaturated fat: A fat made of polyunsaturated fatty acids. Safflower oil and corn oil are polyunsaturated fats. Polyunsaturated fats tend to lower levels of both HDL-cholesterol and LDL-cholesterol in the blood.</li> <li><strong>Saturated fatty acid</strong><br /> A fatty acid that has the maximum possible number of hydrogen atoms attached to every carbon atom. It is said to be "saturated" with hydrogen atoms. Saturated fatty acids are mostly found in animal products such as meat and whole milk.</li> <li><strong>Saturated fat</strong><br /> A fat made of saturated fatty acids. Butter and lard are saturated fats. Saturated fats tend to raise levels of LDL-cholesterol ("bad" cholesterol) in the blood. Elevated levels of LDL-cholesterol are associated with heart disease.</li> <li><strong>Trans fatty acid</strong><br /> A polyunsaturated fatty acid in which some of the missing hydrogen atoms have been put back in a chemical process called hydrogenation. Trans fatty acids are the building blocks of hydrogenated fats.</li> </ul> </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-food-sciences/dairy-chemistry" hreflang="en">Dairy Chemistry</a></div> </div> Mon, 19 Jun 2017 19:21:04 +0000 Anonymous 91 at https://drinc.ucdavis.edu What is the Smoke Point of Butter? https://drinc.ucdavis.edu/dairy-food-sciences/what-smoke-point-butter <span class="field field--name-title field--type-string field--label-hidden">What is the Smoke Point of Butter?</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 19, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-food-sciences.rss" addthis:title="Dairy Food Sciences" addthis:description="There is not an easy answer to this one. Typical smoke points are provided in the table below. The smoke point is a straightforward measurement determined by heating the oil until visible smoke appears coming off the surface. It should be emphasized that these values are not absolute but approximations that vary depending on various aspects of the oil and its history. The smokepoint of oil depends to a very large extent on its purity and age at the time of measurement. The smokepoint endpoint varies with aging of the oil, the same oil will deteriorate with time and thus, one cannot be sure of the smokepoint staying the same for the same oil. Clarified butter, is significantly more stable and has a higher smoke point than butter in which there remains 20% milk, but even in clarified butter the smoke point is not constant. The smoke point is variable depending on how it was clarified, how long it has been stored, etc. Clarified butters are typically produced in &#039;cottage&#039; environments, and the amount of impurities varies a great deal. This means that the quality of preparation has more to do with the temperature at which butter begins to smoke than anything else. It is recommended to test the clarified butter for its smokepoint and if the method of preparation of the clarified butter is satisfactory for that application, fine; otherwise attempt to purify the butter oil more carefully. Ironically, rendered animal fats especially tallow, traditionally makes the best edible oil on a performance basis, but with the public perception that these fats are inordinately harmful to health, it is difficult to obtain them anymore. Name Uses Melting Point* Smoking Point* Butter, whole Baking, cooking 95°F/36°C 300°F/150°C Butter, clarified Cooking 95°F/36°C 300°F/150°C Coconut oil Coatings, confectionary, shortening 75°F/24°C 350°F/175°C Corn oil Frying, salad dressings, shortening 12°F/-11°C 450°F/230°C Cottonseed oil Margarine, salad dressings, shortening 55°F/13°C 420°F/215°C Frying fat Frying 105°F/40°C 465°F/240°C Lard Baking, booking, specialty items 92°F/33°C 375°F/190°C Olive oil Cooking, salad dressings 32°F/0°C 375°F/190°C Peanut oil Frying, margarine, salad dressings, shortening 28°F/-2°C 440°F/225°C Safflower oil Margarine, mayonnaise, salad dressings. 2°F/-17°C 510°F/265°C Shortening, emulsified vegetable Baking, frying, shortening 115°F/46°C 325°F/165°C Soybean oil Margarine, salad dressings, shortening -5°F/-20°C 495°F/257°C Sunflower oil Cooking, margarine, salad dressings, shortening 2°F/-17°C 440°F/225°C From The New Professional Chef, 6th edition * 1996, by The Culinary Institute of America, published by John Wiley &amp; Sons "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "There is not an easy answer to this one. Typical smoke points are provided in the table below. The smoke point is a straightforward measurement determined by heating the oil until visible smoke appears coming off the surface. It should be emphasized that these values are not absolute but approximations that vary depending on various aspects of the oil and its history. The smokepoint of oil depends to a very large extent on its purity and age at the time of measurement." } } </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>There is not an easy answer to this one. Typical smoke points are provided in the table below. The smoke point is a straightforward measurement determined by heating the oil until visible smoke appears coming off the surface. It should be emphasized that these values are not absolute but approximations that vary depending on various aspects of the oil and its history. The smokepoint of oil depends to a very large extent on its purity and age at the time of measurement. The smokepoint endpoint varies with aging of the oil, the same oil will deteriorate with time and thus, one cannot be sure of the smokepoint staying the same for the same oil. Clarified butter, is significantly more stable and has a higher smoke point than butter in which there remains 20% milk, but even in clarified butter the smoke point is not constant. The smoke point is variable depending on how it was clarified, how long it has been stored, etc. Clarified butters are typically produced in 'cottage' environments, and the amount of impurities varies a great deal. This means that the quality of preparation has more to do with the temperature at which butter begins to smoke than anything else.</p> <p>It is recommended to test the clarified butter for its smokepoint and if the method of preparation of the clarified butter is satisfactory for that application, fine; otherwise attempt to purify the butter oil more carefully. Ironically, rendered animal fats especially tallow, traditionally makes the best edible oil on a performance basis, but with the public perception that these fats are inordinately harmful to health, it is difficult to obtain them anymore.</p> <table><tbody><tr><td> <div><strong>Name</strong></div> </td> <td> <div><strong>Uses</strong></div> </td> <td> <div><strong>Melting Point*</strong></div> </td> <td> <div><strong>Smoking Point*</strong></div> </td> </tr><tr><td>Butter, whole</td> <td>Baking, cooking</td> <td>95°F/36°C</td> <td>300°F/150°C</td> </tr><tr><td>Butter, clarified</td> <td>Cooking</td> <td>95°F/36°C</td> <td>300°F/150°C</td> </tr><tr><td>Coconut oil</td> <td>Coatings, confectionary, shortening</td> <td>75°F/24°C</td> <td>350°F/175°C</td> </tr><tr><td>Corn oil</td> <td>Frying, salad dressings, shortening</td> <td>12°F/-11°C</td> <td>450°F/230°C</td> </tr><tr><td>Cottonseed oil</td> <td>Margarine, salad dressings, shortening</td> <td>55°F/13°C</td> <td>420°F/215°C</td> </tr><tr><td>Frying fat</td> <td>Frying</td> <td>105°F/40°C</td> <td>465°F/240°C</td> </tr><tr><td>Lard</td> <td>Baking, booking, specialty items</td> <td>92°F/33°C</td> <td>375°F/190°C</td> </tr><tr><td>Olive oil</td> <td>Cooking, salad dressings</td> <td>32°F/0°C</td> <td>375°F/190°C</td> </tr><tr><td>Peanut oil</td> <td>Frying, margarine, salad dressings, shortening</td> <td>28°F/-2°C</td> <td>440°F/225°C</td> </tr><tr><td>Safflower oil</td> <td>Margarine, mayonnaise, salad dressings.</td> <td>2°F/-17°C</td> <td>510°F/265°C</td> </tr><tr><td>Shortening, emulsified vegetable</td> <td>Baking, frying, shortening</td> <td>115°F/46°C</td> <td>325°F/165°C</td> </tr><tr><td>Soybean oil</td> <td>Margarine, salad dressings, shortening</td> <td>-5°F/-20°C</td> <td>495°F/257°C</td> </tr><tr><td>Sunflower oil</td> <td>Cooking, margarine, salad dressings, shortening</td> <td>2°F/-17°C</td> <td>440°F/225°C</td> </tr></tbody></table><p>From The New Professional Chef, 6th edition * 1996, by The Culinary Institute of America, published by John Wiley &amp; Sons</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-food-sciences/dairy-chemistry" hreflang="en">Dairy Chemistry</a></div> </div> Mon, 19 Jun 2017 19:18:55 +0000 Anonymous 86 at https://drinc.ucdavis.edu Introduction to Bacteria https://drinc.ucdavis.edu/dairy-food-sciences/introduction-bacteria <span class="field field--name-title field--type-string field--label-hidden">Introduction to Bacteria</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 19, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-food-sciences/56/feed" addthis:title="" addthis:description="Bacterial Names Scientists use two names to describe each kind of bacteria. The first is the genus name and second is the species name. When the names of the species and genus are written, the are italicized, or underlined. The genus name usually refers to the group to which the bacterium belongs, somewhat like our human family names, except it is listed first. Many times the genus and species names (in the Latin or Greek language) are selected to describe some general feature of the bacterium. For example, the word used to describe the genus name, Streptococcus, tells us that it is a sphere-shaped cell (coccus) and that it occurs in chains (strepto). The species name is more specific and usually refers to the activity or habit of the organism. The species name lactis tells us that is associated with milk. To illustrate, then, we have the most common bacterium in dairy work: Streptococcus lactis. Once one becomes familiar with the various types of bacteria important to your work, &quot;nicknames&quot; are often used to describe the species of bacteria. For example, Streptococcus lactis becomes &quot;Strept. lactis&quot;. If you want to refer to more than one species of bacteria that have some common characteristics, you can use another nickname, like Streps, referring to those several species of bacteria with characteristics like those found in the genus Streptococcus. One nickname commonly used in the dairy industry is E. coli which is short for Escherichia coli. With sometimes difficult names to pronounce, it is no wonder that people prefer bacterial nicknames! Bacteria Are Very Small One of the most important things to remember about bacteria is their extreme smallness. The fact that they cannot be seen with the unaided eye is one of the chief reasons they are not given the prime consideration they should by people in the dairy and food industries. The average bacterial cell is 1/25,000 of an inch in length and even smaller in diameter. In other words, one could place 25,000 bacteria cells, side by side, on an inch-long line. By contrast, if 25,000 people were lined up shoulder to shoulder, they would make a line over 18 miles long. For us to see these incredibly small living things, a microscope with a magnification of over 800 power or more is needed. In contrast, most binoculars used to observe sporting evens magnify objects about 7 to 10 power. So if these bacteria are too small to see with the eye, how does one know they are present in a food? The process we use is to plate the food being examined to determine if bacteria are present. One takes a sample of food being examined and places a small portion of it on an agar that contains food on which bacteria will grow. The agar, a gelatin-like substance containing the bacterial food, is actually placed in a Petri plate, a shallow round dish with a cover. A small portion of the food being examined is spread over the surface of the agar. The amount of food being &quot;plated&quot; depending on the suspected number of bacteria in the food. For foods containing only a few bacteria, up to one gram (g) or milliliter (mL) will be &quot;plated&quot;. For foods heavily contaminated with bacteria, one-millionth or a gram or mL of the food would be plated. The food is diluted with sterile water to achieve this small amount on the agar in the Petri plate. If bacteria are present they grow rapidly producing offspring that within 12 to 48 hours will produce a &quot;mound&quot; of bacteria in one spot. We can see this mound and call it a colony. The assumption is that each colony originated from one bacterial cell 12 to 36 hours ago. If this assumption is true--sometimes it is not-likely one can calculate the number of bacteria in the original food placed on the agar in the Petri dish by knowing how much food was placed on the plate originally. Bacterial Shapes If one were to look at bacteria through a microscope, one would notice that the bacteria come in a variety of shapes. The most common are cocci (cock&#039;eye), bacilli (bah-sill&#039;eye) and sprialla (spi-rill&#039;-lah). The cocci-shaped bacteria are spheres, the bacilli are rod-shaped, while spirilla are shaped like corkscrews. Some bacteria have other shapes, but these bacteria are generally of little importance to the food and dairy industries. Good &amp; Bad Bacteria Bacteria can be classified by their habits as they relate to human activities. The overwhelming majority of bacteria are harmless to humans. These bacteria are important to humans because they play a role in the ecology of life, by decomposing wastes, both natural and man-made, for example and created nitrogen fertilizer at the root zones of certain crops. Bacteria can also be used purposely by people to make foods. For example, the group of various bacteria collectively called the lactic acid bacteria are used for the manufacture of cultured dairy foods like sour cream. To manufacture sour cream, the species of bacteria Streptococcus lactic is added directly to the 18% cream. These bacteria grow in the cream incubated at 70 degrees producing lactic acid. The lactic acid causes the cream to thicken and cause the flavors which are ascribe to sour cream. Careful selection of the right bacterial type to be used in food manufacture has lead to a variety of cultured food, foods to which carefully selected species of bacteria have been added for their manufacture. For example, most all of our cheeses owe their unique flavors and textures to bacterial growth. San Francisco sourdough bread would not be sour (acid taste) if it were not for the lactic acid bacteria called Streptococcus sanfranciscus. growing in the dough during the time the yeast is growing and causing the dough to rise. Then there are bacterial types that are capable of spoiling foods -spoilage bacteria- or causing sickness or death in people -pathogens. These bacteria are in the minority, but they are well known. Occasionally, one species of bacteria can be categorized as either beneficial or harmful. Here&#039;s a case in point: We use bacteria called Streptococcus lactis to make buttermilk. We encourage its growth by adding it directly to the milk and allowing it to &quot;sour&quot; the milk--that&#039;s buttermilk. On the other hand, if our fresh milk is soured -spoiled- by these bacteria, then these bacteria are considered to be &quot;harmful&quot; spoilage agents. What Bacteria Eat Bacteria like about the same things to eat that people like. They like meat, cake, bread, water, and milk. Some have food requirements that are very much like those of humans because they need performed proteins, vitamins, and so on. These types of bacteria are called &quot;fastidious&quot;. Other bacteria can get along quite well on the simple chemicals, like nitrogen, minerals and an energy source such as sugar. These types of bacteria can then manufacture all the proteins, vitamins, fats, and carbohydrates they need from these very simple foods. Just as we have championed milk as &quot;Nature&#039;s most nearly perfect food,&quot; bacteria also find milk to be one of the best places in which to thrive, for milk furnished almost everything needed for growth, vitamins, proteins, sugar, and water. To consume the food in its environment, the bacteria draw the molecules that make up the food and that are dissolved in the water through their outer membrane and into the inside of their cell. Here the food is digested by bacterial enzymes. The &quot;waste material&quot; of digestion is then passed out through the cell into the environment surrounding the cell. It is this &quot;waste material&quot; that passed out of the cell that causes the changes in our food. In the cases of some pathogenic bacteria, the some of the waste materials are toxins that produce disease and illness. With the bacteria used in making buttermilk or other cultured dairy foods, the waste is lactic acid, which, when its concentration is just right (0.9%), causes the milk to curdle and taste sour--deliciously tasty to some! Harmful Toxins Produced by Some Bacteria Most everyone is familiar with the instances of food poisoning. One of the most common is caused by a bacterium called Staphylococcus aureus, an organism that produces a heat-stable toxin during its growth in some foods. When a food containing the toxin produced by these bacteria is consumed, the person becomes very sick for 24 to 48 hours. However, death rarely results. There have been cases of food poisoning of this type from eating dairy products. The point here is that although these staph bacteria are killed by pasteurization, the toxin is not destroyed. Thus, control of the growth of the bacterium is essential, for if it allowed to grow in food, it could produce the toxin. Of course, the best control is to keep the organism out of the food in the first place. That&#039;s why we wash hands after leaving the restrooms, wash and sanitize equipment that comes in contact with food, etc. Obviously, the food industry is doing a great job at keeping this and other food-poisoning bacteria from processed foods since but 5% of food poisoning problem originate at the food processing plant. Among the pathogenic bacteria that cause disease in man are Brucella abortus, which causes undulant fever, and various species of Salmonella which cause a disease called salmonellosis. It should be remembered that various food poisoning and pathogenic bacteria can inhabit the udder of a cow, and some can cause illness in people if the milk is consumed unpasteurized. There is no assurance that cow or goat milk that is tested and shown to be pathogen free on one day cannot acquire harmful bacteria the next day. Frequently, there is no outward sign in the cow that indicates that this has occurred. How Bacteria Multiply Bacteria multiply by splitting into halves, a process called binary fission. Under the most favorable conditions one bacterial cell will divide into two cells in about 20 to 30 minutes. Twenty minutes later, these two cells will elongate and split into four cells. Then after 20 more minutes, each of the four cells will divide into eight cells and so on. It&#039;s called a logarithmic progression (&quot;log growth&quot;, as the bacteriologist call it). For example, 1 cell ‘ 2 cells ‘ 4 cells ‘ 8 cells ‘ 16 cells ‘ 32 cells ‘ 64 cells ‘ 128 cells ‘ 256 cells ‘ 512 cells ‘ 1024 cells, etc. In the previous examples one bacterial cell, multiplying about every 20 minutes, increases it&#039;s number in less than 3 hours to around 1020 cells. In 36 hours of continuous, unrestricted growth, there would be enough bacteria to fill 200 five-ton trucks! Obviously, bacteria do not multiply indefinitely, so what does control bacterial growth? One factor is temperature. Different Bacteria have Different Temperature Requirements Bacteria like different temperatures for growth. The largest and most common group is called mesophilic (mess-o-fill&#039;-ik). These bacteria are somewhat like people in that they prefer moderate temperatures for growth. With this group the &quot;best&quot;--that is, the most rapid growth is around 70 to 98 degrees. The precise &quot;best&quot; growth does vary with the species of bacteria. The mesophiles can also grow down to 45 degrees and up to 110 degrees, but do so more slowly. In the bacterial world, some like it hot! These bacteria live and multiply best at approximately 130 degrees F. but can grow anywhere between 110 and 190 degrees F. They are referred to as the thermophilic (ther-mo-fill&#039;-ik) group. Contrary to the belief of some people, cold or freezing does not always kill bacteria. In most cases it just stops or slows down their growth. Extended freezing, however, will slowly kill them. Psychrophilic (sigh-crow-fill&#039;-ik) bacteria will grow from 32 to 90 degrees F. with most having their &quot;best&quot; growth around 50 to 70 degrees. Because they grow better NOT best than the mesophilic bacteria at refrigerated temperatures--32 to 45 degrees--, this group is most often responsible for spoilage in refrigerated foods. So how does one control bacterial growth with temperature. If you have a food that is given a &quot;light&quot; heat treatment, like pasteurization, the food must be kept cold so that the growth of any spoilage bacteria surviving the pasteurization process is slowed. (The pasteurization process is designed to kill all pathogens, but not all spoilage bacteria). Obviously cold storage does not stop all bacterial growth since spoilage does eventually occur. But the colder you store the product the longer it will take for the spoilage bacteria to grow and spoil the food. In the dairy and perishable food industries we say, &quot;Life begins at 40&quot;--(degrees, that is). Keep the food at 40 or less and you will get the shelf life you need with a properly processed food. Examples of Control of Bacteria There are other ways that one can control the growth of bacteria. Bacteria need water to grow and even though some of them have the ability to resist long drying out periods, keeping things dry will stop growth and in some instances will kill them. Therefore, it is a good policy to keep utensils and some equipment dry when not in use. Remember, too, that the bacteria responsible for spoilage of foods (mesophilic and psychrophiles) can be killed by hot water. Ten minutes at 150 degrees F. will be sufficient. And, germicides such as chlorine and quaternary ammonium compounds are also effective. Bacteria must eat. And milkstone, which is a dried milk-mineral deposit, and other mineral deposits are good food sources. Therefore, it is necessary to keep all equipment that comes in contact with the food scrupulously cleaned, and sanitized. Likewise the environment in which the food is processed also must be kept cleaned and sanitized. Bacteria from the environment can be &quot;transported&quot; to the food processing areas on hands, feet, clothing and by other unclean equipment. Bacteria can even &quot;float&quot; in on air currents and splashing water can dislodge bacteria from surfaces and make them airborne. These airborne bacteria can eventually contaminate cleaned surfaces. "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "Bacterial Names Scientists use two names to describe each kind of bacteria. The first is the genus name and second is the species name. When the names of the species and genus are written, the are italicized, or underlined. The genus name usually refers to the group to which the bacterium belongs, somewhat like our human family names, except it is listed first." } } </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"><h3>Bacterial Names</h3> <p><img alt="Bug" data-entity-type="file" data-entity-uuid="c2a45dc9-a93c-4e28-8a46-0438cb25f621" src="/sites/g/files/dgvnsk1036/files/inline-images/bug.gif" class="align-right" />Scientists use two names to describe each kind of bacteria. The first is the genus name and second is the species name. When the names of the species and genus are written, the are italicized, or underlined. The genus name usually refers to the group to which the bacterium belongs, somewhat like our human family names, except it is listed first. Many times the genus and species names (in the Latin or Greek language) are selected to describe some general feature of the bacterium. For example, the word used to describe the genus name, Streptococcus, tells us that it is a sphere-shaped cell (coccus) and that it occurs in chains (strepto). The species name is more specific and usually refers to the activity or habit of the organism. The species name lactis tells us that is associated with milk. To illustrate, then, we have the most common bacterium in dairy work: Streptococcus lactis.</p> <p>Once one becomes familiar with the various types of bacteria important to your work, "nicknames" are often used to describe the species of bacteria. For example, Streptococcus lactis becomes "Strept. lactis". If you want to refer to more than one species of bacteria that have some common characteristics, you can use another nickname, like Streps, referring to those several species of bacteria with characteristics like those found in the genus Streptococcus. One nickname commonly used in the dairy industry is E. coli which is short for Escherichia coli. With sometimes difficult names to pronounce, it is no wonder that people prefer bacterial nicknames!</p> <h3>Bacteria Are Very Small</h3> <p>One of the most important things to remember about bacteria is their extreme smallness. The fact that they cannot be seen with the unaided eye is one of the chief reasons they are not given the prime consideration they should by people in the dairy and food industries. The average bacterial cell is 1/25,000 of an inch in length and even smaller in diameter. In other words, one could place 25,000 bacteria cells, side by side, on an inch-long line. By contrast, if 25,000 people were lined up shoulder to shoulder, they would make a line over 18 miles long. For us to see these incredibly small living things, a microscope with a magnification of over 800 power or more is needed. In contrast, most binoculars used to observe sporting evens magnify objects about 7 to 10 power.</p> <p>So if these bacteria are too small to see with the eye, how does one know they are present in a food? The process we use is to plate the food being examined to determine if bacteria are present. One takes a sample of food being examined and places a small portion of it on an agar that contains food on which bacteria will grow. The agar, a gelatin-like substance containing the bacterial food, is actually placed in a Petri plate, a shallow round dish with a cover. A small portion of the food being examined is spread over the surface of the agar. The amount of food being "plated" depending on the suspected number of bacteria in the food. For foods containing only a few bacteria, up to one gram (g) or milliliter (mL) will be "plated". For foods heavily contaminated with bacteria, one-millionth or a gram or mL of the food would be plated. The food is diluted with sterile water to achieve this small amount on the agar in the Petri plate. If bacteria are present they grow rapidly producing offspring that within 12 to 48 hours will produce a "mound" of bacteria in one spot. We can see this mound and call it a colony. The assumption is that each colony originated from one bacterial cell 12 to 36 hours ago. If this assumption is true--sometimes it is not-likely one can calculate the number of bacteria in the original food placed on the agar in the Petri dish by knowing how much food was placed on the plate originally.</p> <h3>Bacterial Shapes</h3> <p>If one were to look at bacteria through a microscope, one would notice that the bacteria come in a variety of shapes. The most common are cocci (cock'eye), bacilli (bah-sill'eye) and sprialla (spi-rill'-lah). The cocci-shaped bacteria are spheres, the bacilli are rod-shaped, while spirilla are shaped like corkscrews. Some bacteria have other shapes, but these bacteria are generally of little importance to the food and dairy industries.</p> <h3>Good &amp; Bad Bacteria</h3> <p>Bacteria can be classified by their habits as they relate to human activities. The overwhelming majority of bacteria are harmless to humans. These bacteria are important to humans because they play a role in the ecology of life, by decomposing wastes, both natural and man-made, for example and created nitrogen fertilizer at the root zones of certain crops.</p> <p>Bacteria can also be used purposely by people to make foods. For example, the group of various bacteria collectively called the lactic acid bacteria are used for the manufacture of cultured dairy foods like sour cream. To manufacture sour cream, the species of bacteria Streptococcus lactic is added directly to the 18% cream. These bacteria grow in the cream incubated at 70 degrees producing lactic acid. The lactic acid causes the cream to thicken and cause the flavors which are ascribe to sour cream. Careful selection of the right bacterial type to be used in food manufacture has lead to a variety of cultured food, foods to which carefully selected species of bacteria have been added for their manufacture. For example, most all of our cheeses owe their unique flavors and textures to bacterial growth. San Francisco sourdough bread would not be sour (acid taste) if it were not for the lactic acid bacteria called Streptococcus sanfranciscus. growing in the dough during the time the yeast is growing and causing the dough to rise.</p> <p>Then there are bacterial types that are capable of spoiling foods -spoilage bacteria- or causing sickness or death in people -pathogens. These bacteria are in the minority, but they are well known. Occasionally, one species of bacteria can be categorized as either beneficial or harmful. Here's a case in point: We use bacteria called Streptococcus lactis to make buttermilk. We encourage its growth by adding it directly to the milk and allowing it to "sour" the milk--that's buttermilk. On the other hand, if our fresh milk is soured -spoiled- by these bacteria, then these bacteria are considered to be "harmful" spoilage agents.</p> <h3>What Bacteria Eat</h3> <p>Bacteria like about the same things to eat that people like. They like meat, cake, bread, water, and milk. Some have food requirements that are very much like those of humans because they need performed proteins, vitamins, and so on. These types of bacteria are called "fastidious".</p> <p>Other bacteria can get along quite well on the simple chemicals, like nitrogen, minerals and an energy source such as sugar. These types of bacteria can then manufacture all the proteins, vitamins, fats, and carbohydrates they need from these very simple foods.</p> <p>Just as we have championed milk as "Nature's most nearly perfect food," bacteria also find milk to be one of the best places in which to thrive, for milk furnished almost everything needed for growth, vitamins, proteins, sugar, and water.</p> <p>To consume the food in its environment, the bacteria draw the molecules that make up the food and that are dissolved in the water through their outer membrane and into the inside of their cell. Here the food is digested by bacterial enzymes. The "waste material" of digestion is then passed out through the cell into the environment surrounding the cell.</p> <p>It is this "waste material" that passed out of the cell that causes the changes in our food. In the cases of some pathogenic bacteria, the some of the waste materials are toxins that produce disease and illness. With the bacteria used in making buttermilk or other cultured dairy foods, the waste is lactic acid, which, when its concentration is just right (0.9%), causes the milk to curdle and taste sour--deliciously tasty to some!</p> <h3>Harmful Toxins Produced by Some Bacteria</h3> <p>Most everyone is familiar with the instances of food poisoning. One of the most common is caused by a bacterium called Staphylococcus aureus, an organism that produces a heat-stable toxin during its growth in some foods. When a food containing the toxin produced by these bacteria is consumed, the person becomes very sick for 24 to 48 hours. However, death rarely results.</p> <p>There have been cases of food poisoning of this type from eating dairy products. The point here is that although these staph bacteria are killed by pasteurization, the toxin is not destroyed. Thus, control of the growth of the bacterium is essential, for if it allowed to grow in food, it could produce the toxin. Of course, the best control is to keep the organism out of the food in the first place. That's why we wash hands after leaving the restrooms, wash and sanitize equipment that comes in contact with food, etc. Obviously, the food industry is doing a great job at keeping this and other food-poisoning bacteria from processed foods since but 5% of food poisoning problem originate at the food processing plant.</p> <p>Among the pathogenic bacteria that cause disease in man are Brucella abortus, which causes undulant fever, and various species of Salmonella which cause a disease called salmonellosis. It should be remembered that various food poisoning and pathogenic bacteria can inhabit the udder of a cow, and some can cause illness in people if the milk is consumed unpasteurized. There is no assurance that cow or goat milk that is tested and shown to be pathogen free on one day cannot acquire harmful bacteria the next day. Frequently, there is no outward sign in the cow that indicates that this has occurred.</p> <h3>How Bacteria Multiply</h3> <p>Bacteria multiply by splitting into halves, a process called binary fission. Under the most favorable conditions one bacterial cell will divide into two cells in about 20 to 30 minutes. Twenty minutes later, these two cells will elongate and split into four cells. Then after 20 more minutes, each of the four cells will divide into eight cells and so on. It's called a logarithmic progression ("log growth", as the bacteriologist call it). For example, 1 cell ‘ 2 cells ‘ 4 cells ‘ 8 cells ‘ 16 cells ‘ 32 cells ‘ 64 cells ‘ 128 cells ‘ 256 cells ‘ 512 cells ‘ 1024 cells, etc. In the previous examples one bacterial cell, multiplying about every 20 minutes, increases it's number in less than 3 hours to around 1020 cells. In 36 hours of continuous, unrestricted growth, there would be enough bacteria to fill 200 five-ton trucks! Obviously, bacteria do not multiply indefinitely, so what does control bacterial growth? One factor is temperature.</p> <p>Different Bacteria have Different Temperature Requirements</p> <p>Bacteria like different temperatures for growth. The largest and most common group is called mesophilic (mess-o-fill'-ik). These bacteria are somewhat like people in that they prefer moderate temperatures for growth. With this group the "best"--that is, the most rapid growth is around 70 to 98 degrees. The precise "best" growth does vary with the species of bacteria. The mesophiles can also grow down to 45 degrees and up to 110 degrees, but do so more slowly.</p> <p>In the bacterial world, some like it hot! These bacteria live and multiply best at approximately 130 degrees F. but can grow anywhere between 110 and 190 degrees F. They are referred to as the thermophilic (ther-mo-fill'-ik) group.</p> <p>Contrary to the belief of some people, cold or freezing does not always kill bacteria. In most cases it just stops or slows down their growth. Extended freezing, however, will slowly kill them. Psychrophilic (sigh-crow-fill'-ik) bacteria will grow from 32 to 90 degrees F. with most having their "best" growth around 50 to 70 degrees. Because they grow better NOT best than the mesophilic bacteria at refrigerated temperatures--32 to 45 degrees--, this group is most often responsible for spoilage in refrigerated foods.</p> <p>So how does one control bacterial growth with temperature. If you have a food that is given a "light" heat treatment, like pasteurization, the food must be kept cold so that the growth of any spoilage bacteria surviving the pasteurization process is slowed. (The pasteurization process is designed to kill all pathogens, but not all spoilage bacteria). Obviously cold storage does not stop all bacterial growth since spoilage does eventually occur. But the colder you store the product the longer it will take for the spoilage bacteria to grow and spoil the food. In the dairy and perishable food industries we say, "Life begins at 40"--(degrees, that is). Keep the food at 40 or less and you will get the shelf life you need with a properly processed food.</p> <h3>Examples of Control of Bacteria</h3> <p>There are other ways that one can control the growth of bacteria. Bacteria need water to grow and even though some of them have the ability to resist long drying out periods, keeping things dry will stop growth and in some instances will kill them. Therefore, it is a good policy to keep utensils and some equipment dry when not in use. Remember, too, that the bacteria responsible for spoilage of foods (mesophilic and psychrophiles) can be killed by hot water. Ten minutes at 150 degrees F. will be sufficient. And, germicides such as chlorine and quaternary ammonium compounds are also effective.</p> <p>Bacteria must eat. And milkstone, which is a dried milk-mineral deposit, and other mineral deposits are good food sources. Therefore, it is necessary to keep all equipment that comes in contact with the food scrupulously cleaned, and sanitized. Likewise the environment in which the food is processed also must be kept cleaned and sanitized. Bacteria from the environment can be "transported" to the food processing areas on hands, feet, clothing and by other unclean equipment. Bacteria can even "float" in on air currents and splashing water can dislodge bacteria from surfaces and make them airborne. These airborne bacteria can eventually contaminate cleaned surfaces.</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-food-sciences/dairy-bacteriology" hreflang="en">Dairy Bacteriology</a></div> </div> Mon, 19 Jun 2017 19:16:15 +0000 Anonymous 81 at https://drinc.ucdavis.edu A Survey of Coliforms and Staphylococcus aureus in Cheese Using Impedimetric and Plate Count Methods https://drinc.ucdavis.edu/dairy-food-sciences/survey-coliforms-and-staphylococcus-aureus-cheese-using-impedimetric-and-plate <span class="field field--name-title field--type-string field--label-hidden">A Survey of Coliforms and Staphylococcus aureus in Cheese Using Impedimetric and Plate Count Methods</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 14, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-food-sciences/66/feed" addthis:title="" addthis:description="Downloadable File: A Survey of Coliforms and Staphylococcus aureus in Cheese Using Impedimetric and Plate Count Methods "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "Downloadable File: A Survey of Coliforms and Staphylococcus aureus in Cheese Using Impedimetric and Plate Count Methods " } } </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>Downloadable File: <a href="http://drinc.ucdavis.edu/research/vol51.pdf">A Survey of Coliforms and Staphylococcus aureus in Cheese Using Impedimetric and Plate Count Methods</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-food-sciences/research-articles" hreflang="en">Research Articles</a></div> </div> Wed, 14 Jun 2017 21:05:35 +0000 Anonymous 236 at https://drinc.ucdavis.edu Association Affairs -- Survey of the Members of the American Dairy Science Association https://drinc.ucdavis.edu/dairy-food-sciences/association-affairs-survey-members-american-dairy-science-association <span class="field field--name-title field--type-string field--label-hidden">Association Affairs -- Survey of the Members of the American Dairy Science Association</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 14, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-food-sciences/66/feed" addthis:title="" addthis:description="Downloadable File: Association Affairs -- Survey of the Members of the American Dairy Science Association "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "Downloadable File: Association Affairs -- Survey of the Members of the American Dairy Science Association " } } </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>Downloadable File: <a href="http://drinc.ucdavis.edu/research/vol73no5.pdf">Association Affairs -- Survey of the Members of the American Dairy Science Association</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-food-sciences/research-articles" hreflang="en">Research Articles</a></div> </div> Wed, 14 Jun 2017 21:04:46 +0000 Anonymous 231 at https://drinc.ucdavis.edu Cheese Mites https://drinc.ucdavis.edu/dairy-food-sciences/cheese-mites <span class="field field--name-title field--type-string field--label-hidden">Cheese Mites</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 14, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-food-sciences/66/feed" addthis:title="" addthis:description="Downloadable File: Cheese Mites "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "Downloadable File: Cheese Mites " } } </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>Downloadable File: <a href="http://drinc.ucdavis.edu/research/cheese_mites.pdf">Cheese Mites</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-food-sciences/research-articles" hreflang="en">Research Articles</a></div> </div> Wed, 14 Jun 2017 21:04:04 +0000 Anonymous 226 at https://drinc.ucdavis.edu Distribution of Protein in California Milk in 1983 https://drinc.ucdavis.edu/dairy-food-sciences/distribution-protein-california-milk-1983 <span class="field field--name-title field--type-string field--label-hidden">Distribution of Protein in California Milk in 1983</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 14, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-food-sciences/66/feed" addthis:title="" addthis:description="Downloadable File: Distribution of Protein in California Milk in 1983 "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "Downloadable File: Distribution of Protein in California Milk in 1983 " } } </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>Downloadable File: <a href="http://drinc.ucdavis.edu/research/vol71no9.pdf">Distribution of Protein in California Milk in 1983</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-food-sciences/research-articles" hreflang="en">Research Articles</a></div> </div> Wed, 14 Jun 2017 21:03:07 +0000 Anonymous 221 at https://drinc.ucdavis.edu Effect of Storage on Tocopherol and Carotene Concentration in Alfalfa Hay https://drinc.ucdavis.edu/dairy-food-sciences/effect-storage-tocopherol-and-carotene-concentration-alfalfa-hay <span class="field field--name-title field--type-string field--label-hidden">Effect of Storage on Tocopherol and Carotene Concentration in Alfalfa Hay</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 14, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-food-sciences/66/feed" addthis:title="" addthis:description="Downloadable File: Effect of Storage on Tocopherol and Carotene Concentration in Alfalfa Hay "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "Downloadable File: Effect of Storage on Tocopherol and Carotene Concentration in Alfalfa Hay " } } </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>Downloadable File: <a href="http://drinc.ucdavis.edu/research/vol61no7.pdf">Effect of Storage on Tocopherol and Carotene Concentration in Alfalfa Hay</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-food-sciences/research-articles" hreflang="en">Research Articles</a></div> </div> Wed, 14 Jun 2017 20:49:02 +0000 Anonymous 216 at https://drinc.ucdavis.edu Factors Affecting Iodine Concentration of Milk of Individual Cows https://drinc.ucdavis.edu/dairy-food-sciences/factors-affecting-iodine-concentration-milk-individual-cows <span class="field field--name-title field--type-string field--label-hidden">Factors Affecting Iodine Concentration of Milk of Individual 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 14, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-food-sciences/66/feed" addthis:title="" addthis:description="Downloadable File: Factors Affecting Iodine Concentration of Milk of Individual Cows "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "Downloadable File: Factors Affecting Iodine Concentration of Milk of Individual Cows " } } </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>Downloadable File: <a href="http://drinc.ucdavis.edu/research/vol66no5.pdf">Factors Affecting Iodine Concentration of Milk of Individual Cows</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-food-sciences/research-articles" hreflang="en">Research Articles</a></div> </div> Wed, 14 Jun 2017 20:48:12 +0000 Anonymous 211 at https://drinc.ucdavis.edu Factors Relating to Development of Spontaneous Oxidized Flavor in Raw Milk https://drinc.ucdavis.edu/dairy-food-sciences/factors-relating-development-spontaneous-oxidized-flavor-raw-milk <span class="field field--name-title field--type-string field--label-hidden">Factors Relating to Development of Spontaneous Oxidized Flavor in Raw Milk</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 14, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-food-sciences.rss" addthis:title="Dairy Food Sciences" addthis:description="Downloadable File: Factors Relating to Development of Spontaneous Oxidized Flavor in Raw Milk "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "Downloadable File: Factors Relating to Development of Spontaneous Oxidized Flavor in Raw 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"><p>Downloadable File: <a href="http://drinc.ucdavis.edu/research/vol59no2.pdf">Factors Relating to Development of Spontaneous Oxidized Flavor in Raw Milk</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-food-sciences/research-articles" hreflang="en">Research Articles</a></div> </div> Wed, 14 Jun 2017 20:40:39 +0000 Anonymous 206 at https://drinc.ucdavis.edu Influence of Feeding Dehydrated Poultry Waste on Composition and Organoleptic Quality of Milk https://drinc.ucdavis.edu/dairy-food-sciences/influence-feeding-dehydrated-poultry-waste-composition-and-organoleptic-quality <span class="field field--name-title field--type-string field--label-hidden">Influence of Feeding Dehydrated Poultry Waste on Composition and Organoleptic Quality of Milk</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 14, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-food-sciences/66/feed" addthis:title="" addthis:description="Downloadable File: Influence of Feeding Dehydrated Poultry Waste on Composition and Organoleptic Quality of Milk "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "Downloadable File: Influence of Feeding Dehydrated Poultry Waste on Composition and Organoleptic Quality of 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"><p>Downloadable File: <a href="http://drinc.ucdavis.edu/research/vol40no1.pdf">Influence of Feeding Dehydrated Poultry Waste on Composition and Organoleptic Quality of Milk</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-food-sciences/research-articles" hreflang="en">Research Articles</a></div> </div> Wed, 14 Jun 2017 19:26:00 +0000 Anonymous 201 at https://drinc.ucdavis.edu Iodine in California Farm Milk: 1985-1986 https://drinc.ucdavis.edu/dairy-food-sciences/iodine-california-farm-milk-1985-1986 <span class="field field--name-title field--type-string field--label-hidden">Iodine in California Farm Milk: 1985-1986</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 14, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-food-sciences/66/feed" addthis:title="" addthis:description="Downloadable File: Iodine in California Farm Milk: 1985-1986 "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "Downloadable File: Iodine in California Farm Milk: 1985-1986 " } } </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>Downloadable File: <a href="http://drinc.ucdavis.edu/research/vol50.pdf">Iodine in California Farm Milk: 1985-1986</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-food-sciences/research-articles" hreflang="en">Research Articles</a></div> </div> Wed, 14 Jun 2017 19:25:06 +0000 Anonymous 196 at https://drinc.ucdavis.edu Iodine in Cow's Milk Produced in the USA in 1980-1981 https://drinc.ucdavis.edu/dairy-food-sciences/iodine-cows-milk-produced-usa-1980-1981 <span class="field field--name-title field--type-string field--label-hidden">Iodine in Cow&#039;s Milk Produced in the USA in 1980-1981</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 14, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-food-sciences/66/feed" addthis:title="" addthis:description="Downloadable File: Iodine in Cow&#039;s Milk Produced in the USA in 1980-1981 "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "Downloadable File: Iodine in Cow&#039;s Milk Produced in the USA in 1980-1981 " } } </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>Downloadable File: <a href="http://drinc.ucdavis.edu/research/vol48.pdf">Iodine in Cow's Milk Produced in the USA in 1980-1981</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-food-sciences/research-articles" hreflang="en">Research Articles</a></div> </div> Wed, 14 Jun 2017 19:24:09 +0000 Anonymous 191 at https://drinc.ucdavis.edu Iodine in Human Milk https://drinc.ucdavis.edu/dairy-food-sciences/iodine-human-milk <span class="field field--name-title field--type-string field--label-hidden">Iodine in Human Milk</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 14, 2017</span> <div class="addthis_toolbox addthis_default_style addthis_32x32_style" addthis:url="https://drinc.ucdavis.edu/dairy-food-sciences.rss" addthis:title="Dairy Food Sciences" addthis:description="Downloadable File: Iodine in Human Milk "> <a class="addthis_button_facebook"></a> <a class="addthis_button_linkedin"></a> <script> var addthis_share = { templates: { twitter: "Downloadable File: Iodine in Human 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"><p>Downloadable File: <a href="http://drinc.ucdavis.edu/research/vol66no6.pdf">Iodine in Human Milk</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-food-sciences/research-articles" hreflang="en">Research Articles</a></div> </div> Wed, 14 Jun 2017 19:23:16 +0000 Anonymous 186 at https://drinc.ucdavis.edu