Milk Quality Terms

Bacterial Count
The number of bacteria just viable or both viable and nonviable depending on method of analysis. As examples, plate counts determine numbers of viable bacteria capable of growth under conditions imposed, whereas direct microscopic counts enumerate all stainable cells both living and dead
Bactericide
An agent or substance capable of destroying bacteria.
Bacteriostatic
A substance that prevents the growth of bacteria but does not kill them.
B.O.D.(Biochemical Oxygen Demand)
The amount of oxygen required to maintain aerobic conditions during decomposition of factory wastes such as whey. The effect of excessive waste in streams is that it uses up dissolved oxygen, thereby creating objectionable conditions and making it impossible for aquatic life to survive.
Casein
The major protein of milk.
CIP (cleaned in place)
Most stainless steel pipelines are cleaned by circulating washing solutions through them.
Coliform Bacteria
The coliform group of bacteria comprises all aerobic and facultatively anaerobic, gram-negative nonspore forming rods capable of fermenting lactose with the production of acid and gas at 90°F (32°C) within 48 hours. While the general source of these organisms is commonly accepted to be the intestinal tract of warm-blooded animals, it is emphasized that bacteria of both fecal and non-fecal origin are members of this group. Typically, these organisms are classified in the genera Escherichia and Enterobacter (formerly Aerobacter); but, in addition, a few lactose-fermenting species of other genera are included in the group. In proportion to the numbers present, the existence of any of these types in dairy products is suggestive of unsanitary conditions or practices during production, processing or storage.
Coliform Count
The coliform bacteria count is used as an index of the level if sanitation and/or water quality employed in the handling and processing of milk products. Coliforms have significance in milk and milk products because (1) they are easily killed during pasteurization and because (2) they are generally regarded to originate from the intestinal tract of warm-blooded animals. Hence, the presence of coliform bacteria in pasteurized milk products is suggestive of unsanitary conditions or practices during processing, packaging; maximum standards for number of coliforms have until now been set at a maximum of 10 per milliliter of gram in pasteurized milk and milk products; however, numbers in pasteurized dairy products should be less than 1 ml., as is the case with up to 90% of samples, if packaging procedures are correct. California standard allows no more than 750 coliforms per mL in raw milk. Less than 100 is considered acceptable.
Enzyme
A complex organic substance that will accelerate (catalyze) specific chemical transformation. For example, lipase, fat splitting, and protease, protein splitting enzymes are always found in milk, and are sometimes involved in milk spoilage.
Escherichia Coli (E. Coli)
Certain serological groups of Escherichia coli are known to produce severe diarrhea in infants and young children. Both animals and man are carriers of Enteropathogenic E. coli, the organisms having been recovered from the milk of healthy animals as well as those with mastitis.
Lab Pasteurized Count
Bacteria that survive specific heat treatments (i.e., vat or high temperature short time (HTST) pasteurization) are usually said to be thermoduric (heat tolerant). A practical laboratory test involves heat treatment of representative raw bulk milk samples at 145°F (63°) for 30 minutes (equivalent of vat pasteurization minimum conditions). The Standard Plate Count method is used to enumerate the surviving microorganisms. In raw milk, less than 100/ml is desirable; more than 750/mL is illegal under California regulations.
Pasteurization
Temperature Time 145°F (63°C) (Batch) 30 minutes 161°F (72°C) (HTST) 15 minutes 191°F (89°C) (HHST) 1.0 second 194°F (90°C) (HHST) 0.5 second 201°F (94°C) (HHST) 0.1 second 204°F (96°C) (HHST) 0.05 second 212°F (100°C) (HHST) 0.01 second 280°F (138°C) (Ultra-pasteurized) 2.0 seconds
P.I. Count
Preliminary Incubation Count - this is a method of counting the bacteria in milk that grow at low temperatures and are not usually counted by the Standard Plate Count method. Incubation of the raw milk sample is at 55°F (13°C) for 18 hours (or other time/temperature combination) prior to plating. Good P.I. counts should be similar to raw milk SPS's, that is less than 20,000/ml. Not all dairy researchers believe this count "adds" to understanding troublesome counts in raw milk.
PPM
Parts pre million. It equals milligrams per kilogram or microliter per liter.
Psychrotrophic
Cold tolerant. It refers to microorganisms that grow at low temperatures, below 45°F (7°C), but have an optimum temperature of 59°F to 70°F (15°C to 21°C). These organisms especially affect the shelf life of refrigerated dairy products, such as cottage cheese.
Quality
A term used to indicate the desirability and/or acceptability of an animal or food product.
Sanitize
To kill or remove injurious microorganisms but not necessarily to sterilize. Dairy equipment is commonly sanitized with hot water or chemicals.
Shelf Life
The time after processing during which a product remains suitable for human consumption, especially the time a food remains palatable and acceptable to consumers.
Standard Plate Count (SPC)
The SPC has long been the primary test for determining the bacterial density (quality) of fresh raw or pasteurized grade A milk. The SPC estimates the total numbers of aerobic type microorganisms. In conducting this procedure, careful consideration must be given to nutrients of plating medium, the temperature and time of incubation, and proper dilution of the sample to avoiding overcrowding of colonies on plates. Samples must be representative, collected with contamination, and stored under conditions that will not allow bacterial growth or destruction (below 40° but above 32°F) (below 4 °C above 0°C), and tested within 36 hours of collection.
Sterilize
To remove or kill all living organisms.

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