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Nutrition 244 > Milk Protein > Flashcards

Milk Protein Flashcards

1
Q

What is the composition of milk?

A

88% Water

  1. 7% Carbs
  2. 3% Fats
  3. 7% Vitamins and Minerals
  • Calcium (300mg/8oz.)
  • Mg2+, P, K, Na, S
  • Riboflavin, B2, A, D
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2
Q

What is milk lacking? (4)

A
  1. No fiber
  2. No Vitamin C
  3. No Vitamin E
  4. No Iron
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3
Q

What is the fat content of milk?

A

3.5-5% fat

  • 66% saturated fat
  • 30% monounsaturated fat
  • 4% polyunsaturated fat
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4
Q

What are the fat globules of fat covered by?

A

It is covered by a membrane.

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5
Q

What is the process of homogenization?

A

Forcing milk through very tiny holes under pressure. It makes the fat globules very small.

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6
Q

What is the carbohydrate content in milk? What are some of its characteristics?

A

Lactose

  • NOT very soluble
  • NOT very sweet
  • Very functional (very reacted in Maillard Browning)
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7
Q

What are the two types of protein found in milk?

A
  1. Casein

2. Whey

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8
Q

Describe Casein.

A

80% of milk protein

Exists as a micelle.

A very complex molecule with many subunits.

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9
Q

What is the isoelectric point of Casein?

A

Isoelectric Point = 4.6

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10
Q

Describe a casein micelle.

A

It is made up of many casein subunits.

Hydrophobic AA are located in the center, while the hydrophilic AA are located on the outside (hydrophilic tail of kappa subunit)

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11
Q

What holds the subunits of the casein micelle together?

A

Ca2+ ions hold the subunits together.

PO4- (phosphate) surrounds the outside of the micelle.

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12
Q

What happens when acid reacts with the PO4- (phosphate) group of the casein?

A

The charges neutralize each other, and the casein micelles come together to form curds.

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13
Q

What is the first step in making many milk products?

A

Lowering the pH

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14
Q

Describe Whey Protein.

A

20% of milk protein.

Composed of lactoglobulins and lactalbumins.

Much smaller than casein.

More water soluble than casein.

Contains Globular Proteins.

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15
Q

What is the relationship between heat and acid to whey protein?

A

It is very sensitive to heat; but not sensitive to acid.

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16
Q

What happens when you heat milk?

A

The whey protein drops to the bottom of the pan.

It can also react with lactose and brown via Maillard.

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17
Q

How do you prevent milk from browning during heating? (3)

A
  1. Constant Stirring
  2. Low Heat
  3. Double Broiler
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18
Q

How is milk graded?

A

It is graded according to bacterial count.

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19
Q

What are the two types of grades? And who pays for this?

A
  1. Grade A
    - lowest bacterial count (10,000 cfu/mL, colony forming units)
  2. Grade B
    - much higher bacterial count
    - used in canned products

Paid for by the dairy industry; voluntary.

20
Q

What are the four processes for milk?

A
  1. Pasteurization
  2. Separation
  3. Homogenization
  4. Fortification
21
Q

What is pasteurization?

A

It is the process of heating milk.

It kills pathogenic bacteria and destroys microorganisms. It also inactivates enzymes and increases shelf-life.

22
Q

The destruction of microorganisms is dependent on what two things?

A

Time and termperature.

23
Q

What is HTST?

A

High temperature, short time.

Used for pasteurizing milk.

160°F for 15 seconds

24
Q

What is UHT?

A

Ultra-high temperature

Used for pasteurizing milk.

280°F for 2 seconds.

25
Q

How are UHT pasteurized milk packaged?

A

They are packaged aseptically.

Stored at room temperature.

26
Q

What is separation of milk and how is it done?

A

You are separating the fat and the milk and you achieve this due to the differences in their densities.

It is done through the use of centrifuges.

27
Q

What is homogenization?

A

It is a mechanical process where the fat is added back.

Milk is pumped under pressure through a screen with tiny holes which breaks up the fat globules, with each fat globule having its own lipoprotein membrane.

The fat is permanently dispersed in a fine emulsion.

28
Q

What is fortification of milk consist of?

A

Vitamin D is added. This will facilitate Ca2+ absorption.

29
Q

Why was milk fortified?

A

It was to prevent a disease called Rickets.

30
Q

What are some milk products?

A

Whole milk -> 3.25-3.3% milk fat
Reduced Fat Milk -> 2% milk fat
Low Fat Milk -> 1% low fat milk
Skim Milk ->

31
Q

What are some milks fortified with?

A

Extra protein or vitamin C?

32
Q

Some milks are made for the lactose intolerant. Why?

A

The lactose intolerant lack the enzyme that is able to breakdown lactose. Therefore, they will add the enzyme lactase inside the milk or acidophilis bacteria.

33
Q

What are the two canned milk products called about in class?

A
  1. Evaporated milk
    - 60% of H2O is removed
  2. Sweetened Condensed milk
    - 50% of H2O is removed
    - 42% of sucrose is added
34
Q

What is a common dried milk product?

A

Non-Fat Dried Milk -> NFDM

It has a longer shelf life since the fat has been removed; it is less susceptible to rancidity.

35
Q

What are cultured milk products?

A

They use lactose fermenting bacteria to produce lactic acid.

This will drop the pH and precepitate casein, which will become thicker in consistency.

This is the first step in the production of yogurt, buttermilk, kefir, sour cream, or cheese.

36
Q

What bacterias are used for yogurt?

A

Streptococcus thermophilis
Lactobacillus bulfaricus
Lactobacillus acidophilus

Probiotics contain live cultures

37
Q

What bacteria is used for buttermilk?

A

Streptococcus lactis.

Contains very little or no butter fat. It is the liquid left over after churning.

38
Q

What bacteria is used for sour cream?

A

Acidified by streptococcus lactis.

Often gums are added to improve texture.

39
Q

What bacteria is used for Kefir?

A

Add lactobacillus caucasius, yeast saccharomyces kefir, and Torula kefir.

It is probiotic that contains a small amount of alcohol that can be slightly carbonated.

40
Q

What can coagulation of casein be done with to make cheese? (3)

A
  1. Acid
  2. Enzymes
  3. Both
41
Q

Look at the 10 step process of cheese.

A

Look at the 10 step process of cheese.

42
Q

What is the isoelectric point of casein?

A

4.6

43
Q

What is rennin used for, how does it work, and where do we get it?

A

Rennin is used for cheese production.

It cleaves the hydrophilic tail from the kappa subunit of casein.

It comes from the stomach lining of a calf -> called chymosin.

44
Q

When would you use the cheese from the 10-step cheese making process to make processed cheese?

A

After cheese making process, but before the aging process.

45
Q

What are the two steps in creating a processed cheese?

A
  1. Apply Heat
  2. Add emulsifiers
  3. Add back liquid
  4. Heat again before aging.

Nutrition 244 (12 decks)

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