2018 ACS Body of Knowledge – Domain 4 – Milk – Bullet points and Terms to Know:
Complete Domain 4 Documents are available by clicking here. Review of Pasteurized Milk Ordinance (PMO) is available by clicking here.
- Milk is made-up of Water, Fat, Protein, Sugar (Lactose) and Minerals.
- Water in cows’ and goats’ milk is approximately 87%, 82% in sheep milk and 81% in buffalo milk. (There are differences depending on breed.)
- Know solids an % in common breeds, including buffalo.
- Butterfat in cows’ milk is 3.7%, in goats’ milk is about 3.6%, sheep milk is about 7.4% and in buffalo milk 8.3%. (There are differences depending on breed.)
- Butterfat content varies from breed to breed. Be sure and familiarize yourself with which breeds have higher butterfat and be able to rank higher to lower (or vice versa).
- Know principle minerals in milk.
- Know common breeds of milk-giving animals: cow, sheep, goat. (You may be asked which cow breed has the highest fat percentage; or which breed gives the highest yield of milk.)
- Lactation periods for common milk-giving mammals.
- Lactation periods: cows 305 days; goats 290-305 days and sheep 240 days. (Again, varies depending on breeds.)
- Milk yield for common milk-giving mammals.
- Milk yield per day: Cows is about 8 gallons; goats 3 to 4 quarts and sheep about 2 quarts. (Again, varies depending on breeds.)
- Definition of drying-off.
- When and why used.
- Lactation periods for common milk-giving mammals.
- Remember that milk is seasonal in terms of fat, protein and yield. Fat and protein content increase the closer to the end of the lactation cycle as yield decreases. When yield is higher, fat and protein are lower.
- Know definition of Calcium Chloride.
- Know definition of demineralization.
- Know difference between Grad A and Grade B milk.
- Factors that affect milk quality.
- Fats, proteins and minerals in milk are used to make cheese.
- Protein important in cheese are the caseins, which increase yield, speed-up coagulation and create a firmer curd.
- Primary mineral to understand is Calcium Phosphate. Calcium Phosphate. Refer to page 124 of American Farmstead Cheese by Paul Kindstedt.
- Lactose is the sugar in milk. Most is washed away with the whey and what remains converts to lactic acid, usually within a few days. With the exception of fresh cheeses, most cheeses aged more than 60 days contain no lactose. (If sugar content listed in ingredients is 0% or 0 grams, then the cheese contains no lactose.)
- Ruminant is a mammal that derives its nutrition from a plant-based diet. The digestion of food occurs in its four stomachs.
- Definition of pasteurized milk: The terms “pasteurization”, “pasteurized” and similar terms shall mean the process of heating every particle of milk or milk product, in properly designed and operated equipment, to one (1) of the temperatures given in the following chart and held continuously at or above that temperature for at least the corresponding specified time: Temperature Time 63ºC (145ºF)* 30 minutes 72ºC (161ºF)* 15 seconds 89ºC (191ºF) 1.0 second 90ºC (194ºF) 0.5 seconds 94ºC (201ºF) 0.1 seconds 96ºC (204ºF) 0.05 seconds 100ºC (212ºF) 0.01 seconds.
- Vat pasteurization (LTLT) – Heating milk for 30 minutes at 145 degrees F.
- HTST and UHT pasteurization definitions.
- Definition of sterilization.
- Definition of Thermization.
- Raw milk definition: Milk from the cow that has not been heat-treated to a temperature higher than the temp when it came from the animal.
- Rennet, necessary to coagulate milk, traditionally is made from an enzyme (Chymosin) found in the 4th stomach of an unweaned ruminant (generally a calf although rennet can come from lambs and kids). The fourth stomach is known as the abomasum. Today, rennets are created in labs, which are cheaper to produce and considered “vegetarian suitable”. Many Portuguese cheeses use thistle for coagulation.
- Somatic Cell Count – measurement of somatic cells (primarily white blood cells) in milk. Caused by infection (generally mastisis). Any number above 400,000 indicates milk is unfit for human consumption.
- Definition of Lactose and importance to those with intolerance.
- Definition of raw milk.
- Starter Culture bacteria are added to milk to start fermentation to form curd. The cultures also dictate the style cheese being made. Cultures affect aroma, texture, flavor. They help break down proteins to create different “finishes” in cheese. (e.g. p. shermani is added to create the gas (CO2) which forms the eyes in swiss-style cheeses)
- Know main cultures and how they work.
- Importance of salt in cheesemaking – includes contributing to lactic acid production, moisture control, rind creation, texture, flavor. Salt can be added at different steps to create different results. (Salting before pressing in cheddars, salting rind after pressing, brine soaking, bring for preserving such as feta and Havarti.)
- Know definition of Pseudomonas fluroescens.
- Understand why microorganisms and enzymes are added to milk and what they do.
- Know major pathogens that can be present in milk.
- Understand pH range as it relates to milk and cheese.
- Review Pasteurized Milk Ordinance Document (PMO)
Terms to know:
Abomasum * Adjuncts * Annatto * Bacteriophage * Beta Carotene * Butterfat * Calcium Chloride * Calcium Phosphate * Casein * Chymosin * Coliform * Cultures * Curds * Enzymes * HTST * Lactase * Lactation * Lactose * Lipases * Lipolysis * Listeria Monocytogenes * Mastitis * Mesophillic * Microbial Rennet * Microflora * Pasteurization * Pathogens * pH * Proteolysis * Pseudomonas fluroescans * Raw Milk * Rennet * Ruminants * Salmonella * Silage – Somatic Cell Count * Staphylococcus aureus * Sterilization * Thermization or Thermalization * UHT * Vat Pasteurization * Water Activity (aw)
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