CHAPTER 12: MILK AND MILK PRODUCTS Flashcards
Milk and milk products sold in North America are produced mostly from what?
Domestic cows.
Milk and dairy products are complex ingredients that contain what?
A mix of proteins, sugar (lactose), vitamins, minerals, emulsifiers, and milk fat.
Are dairy ingredients essential to baked goods?
No, but they are important.
Do the US and Canadian federal governments regulate minimum milk fat amounts in milk and milk products?
Yes, they also regulate pasteurization, maximum allowable bacterial counts, acidity levels, and additives allowed.
Do certain states and provinces have more stringent regulations that are enforced within their borders?
Yes
Are all dairy products sold in North America pasteurized?
Essentially, but certain aged cheeses are an exception.
Why do drink boxes of milk not require refrigeration?
They’re the modern equivalent of canned milk. The milk has been ultra pasteurized, then cooled and specifically packaged under sterile conditions so that the product inside is essentially bacteria free. The process is called aseptic processing, and no preservatives or food irradiation are involved.
Who invented pasteurization?
Louis Pasteur in the mid-1800s
The most common commercial means of pasteurization.
High-temperature, short-time (HTST) pasteurization in which milk is heated to a high temp, at least 161ºF (72ºC) for a minimum of 15 seconds.
What is Ultra high temperature (UHT) pasteurization.
Ultra pasteurization involves heating the product to an even higher temp, often 280ºF (138ºC), for 2 seconds.
Does UHT milk have a slightly different flavor than HTST? Why?
Yes, because milk flavor is very heat sensitive.
Does UHT milk have a longer shelf life? Why?
Yes, because the higher temp is much more lethal to pathogens, destroying essentially all bacteria in milk.
Should UHT products be treated like HTST products?
Yes, unless specifically packaged to prevent the entry of microorganisms.
If fresh milk is taken from the cow and allowed to sit, what rises to the top?
Cream
To prevent cream from rising to the top, most dairy products in North America are what?
Homogenized
What is homogenization?
A process in which milk is forced under high pressure through small openings in a metal plate, forcing milk fat into tiny droplets.
What happens when the droplets form?
Milk proteins and emulsifiers surround each one, forming a protective film that prevents them from reuniting. The tiny droplets stay suspended indefinitely.
Are homogenized dairy products stable emulsions?
Yes, of fat droplets suspended in milk.
Is cream easily separated from milk in a milk separator?
Yes
What is a separator?
A type of centrifuge that spins very quickly, causing cream in milk to separate off because of its lighter density. The process is much faster than relying on gravity.
Milk directly from the cow contains proteins, lactose, vitamins, minerals, and milk fat. But milk is mainly composed of what?
Water
Not counting milk fat, the solids in milk are appropriately called what?
Milk solids, not fat or MSNF.
Other than a slight sweetness, the flavor of milk is relatively _____.
mild
As the amount of milk fat in milks products increases, the flavor becomes ______.
rich (dairy flavor), because most of the dairy flavor is in the fat.
Are small amounts of emulsifiers lecithin and mono- and diglycerides also in milk fat?
Yes, as are carotenoid pigments.
What provides dairy products with a slight yellowish color?
Carotenoid pigments
Mostly, milk fat contains what?
Triglycerides, or fat molecules, especially saturated ones.
% of milk fat, proteins, lactose, water and ash in whole milk.
Milk fat: 3.3% Ash: 0.7% Protein: 3.3% Lactose: 5% Water: 88%
Although whole milk is only 3.5% protein, are these protein important?
Yes
Two proteins in whole milk.
Casein and whey.
Casein proteins are easily coagulated with what?
Acids or enzymes.
Coagulated or clabbered, casein proteins aggregate with one another in a manner somewhat similar to what?
Egg proteins.
Like egg proteins, casein proteins _____ and ____ as they coagulate. This is the basis for manufacturing of what?
thicken, gel; cheeses, yogurt, sour cream, and other cultured dairy products.
When cheese is made, a clear ______ liquid drains from the cheese curd.
greenish
While the coagulated casein proteins form the cheese curd, the clear liquid, known as ______, contains _____ proteins.
whey, whey
What do whey proteins form on the bottom of pans and on the surface of milk when it is heated?
Film
Why must milk not be left unattended on the heat?
Because a film of whey quickly burns onto the pan bottom , running flavor and color.
How can you prevent whey proteins from sticking and coating the bottom of the pan when milk or cream is heated?
Add some or all of the sugar from the recipe before heating.
Whey proteins are just one of the nutrients in whey. Whey is also rich in what?
Lactose, calcium salts, and riboflavin.
The slight greenish tinge in whey is from what?
Riboflavin, one of the B vitamins in milk.
Lactose is also called what?
Milk sugar
Lactose makes up how much of the MSNF of milk?
50%
Lactose’s sweetness, which is about _____ that of sucrose, contributes to the characteristic flavor of _______.
1/5, milk
Is lactose a disaccharide? What molecules?
Yes, consisting of a glucose molecule bonded to galactose.
Unlike most sugars, lactose isn’t what?
Fermented by yeast.
What is lactose intolerance?
Intestinal discomfort when because a persons body does not contain high levels of the enzyme–lactase–that breaks down lactose into glucose and galactose. The undigested lactose passes into the lower intestine, where bacteria break it down and produce acid and gas.
Is lactose intolerance life threatening?
No
What can lactose intolerant people consume?
Products low in lactose such as cultured dairy products and cheese.
What is Lactaid?
A product that contains lactase.
Why is milk treated with Lactaid sweeter than regular milk?
Because glucose and galactose are sweeter than lactose.
Does progressively eating more and more dairy create more enzymes to stop lactose intolerance?
Yes
Fluid milk is classified by what?
Its fat content, which is standardized by the processor.
Range for fat contents in milk.
3.25% or higher for whole milk to essentially 0% for fat free (skim) milk.
The minimum MSNF for milk in the US is what?
8.25%; the rest is water.
MSNF stands for what?
Milk solids non fat
The minimum MSNF for milk in Canada is what?
8.0%; the rest is water.
For freshest dairy flavor, ____ milk is the product of choice.
fluid
What milk is best in baked custards, cream pies, vanilla custard sauce, frozen desserts, and pastry cream?
Fluid milk, not dry powder.
When using fluid milk in yeast doughs, scald it at what temp? Why?
180ºF (82ºC), this denatures whey protein (glutathione) that interferes with gluten development.
What are DMS?
Dry milk solids.
How are dry milk solids made?
By removing most–all but 3-5%–of water from fat-free or whole milk.
How are most DMS made?
Spray-dry process, in which partly evaporated milk is sprayed as a fine mist into a heated chamber. The milk dries almost instantly and falls to the bottom of the chamber as a powder.
Advantages of DMS?
Takes up less space than fluid milk and requires no refrigeration.
When DMS is made from whole milk it is sometimes called what?
Dry whole milk or powdered whole milk.
Do dry whole milk oxidize easily? Why?
Yes, because it contains milk fat.
When DMS is made from fat-free milk it is sometimes called what?
Nonfat dry milk, powdered skim milk, NDM, or NFDM.
What is more common in bakeshops, whole milk powder or nonfat fry milk? Why?
Non-fat dry milk because it lasts longer.
Does DMS have the same fresh dairy flavor as fluid milk?
No, so it should not be used in custards or creams.
What should DMS be used in?
Baked goods such as cookies, breads, and cakes.
Can DMS be purchased with varying amounts of heat treatment?
Yes
High-heat DMS is held at what temp?
190ºF (88ºC) for a minimum of 30 minutes, then dried.
Why is DMS best used in yeast-raised baked goods?
Because the heat treatment denatures whey protein that reduces gluten development and bread quality.
Does heat treatment also increase the ability of milk proteins to absorb water?
Yes
Is low-heat DMS often used in the bakeshop? Why?
No. While is has a fresher taste than high-heat DMS, low-heat DMS does not provide the added benefits to baked goods that high-heat DMS provides.
Where would low-heat DMS be best utilized?
Where dry milk solids are added to increase the solids of ice cream mixes.
Example of low-heat DMS in grocery stores.
Instant nonfat dry milk
How do you use dry milk solids? Conversion.
For every pound of fluid whole milk, use 2 ounces (0.12lbs) DMS and 14 ounces (0.88lbs) water.
Use 120 grams DMS and 880 grams water for every liter of milk.
Can you add DMS to dry ingredients or cream it with fat?
Yes
Does DMS easily mix with water?
No, so it is best not to reconstitute it before use.
Minimum milk fat standards for cream products sold in the US and Canada: Heavy cream
US: 36%
CANADA: -
Minimum milk fat standards for cream products sold in the US and Canada: Whipping cream
US: 30%
CANADA: 32%
Minimum milk fat standards for cream products sold in the US and Canada: Cream
US: -
CANADA: 10%
Minimum milk fat standards for cream products sold in the US and Canada: light cream
US: 18%
CANADA: -
Minimum milk fat standards for cream products sold in the US and Canada: Half-and-Half
US: 10.5%
CANADA: -
Is cream sold in North America pasteurized?
Yes, often under UHT (ultra pasteurized) conditions.
The main advantage of UHT cream is what?
An extended shelf life.
Besides being pasteurized, cream is usually what?
Homogenized
Does homogenized cream make whipping more difficult?
Yes, but many heavy creams and whipping creams contain added emulsifiers and stabilizing gums to aid in whipping.
At very high levels of fat (around _____%) even homogenized creams whips easily.
40
Cream is classified by what?
The amount of milk fat it contains.
