Dairy and Eggs 1

Question 1

Dairying began

Answer 1

Domestication
8000-9000 BCE sheep/goats
Dairying of beef and domestication in 7000 BCE (NW anatolia)

Milking, yogurt and cheesemaking in ancient Egypt (5000 BCE)

Butter making in 2500 BCE mesopotamia

Yogurt, kefir (mare’s milk) and koumiss (alcoholic beverage)
- Zebu and buffalo yogurt in India and butter/ghee

Question 2

Fresh milk consumption history

Answer 2

Fresh milk rarely consumed before 1800’s - most used for butter, cheese and yogurt

1900’s pasteurization

20th century refrigeration

Clean living reform (fear inspired by rise of industrialized society) - promoted milk consumption (considered pure)
- Evangelist movement
Temperance Movement - grains used for cows instead of alcohol

Question 3

Milk definitions under Food and Drug Regulations

Fortification

Skim and evaporated definitions

Answer 3

Milk is lacteal secretion from mammary gland of a cow (unless indicated another mammal)

Must be fortified with vitamin A (lost in skimming process) and D (as public rickets prevention, 300-400 IU)

Skim milk = not more than .3% milk fat
Vitamin A not less than 1200-2500 IU
Vitamin D same (300-400 IU)

Evaporated milk = not less than 25% milk solids and 7.5% milk fat
- Added vitamin C (60-75mg)
- Disodium phosphate + sodium citrate

Question 4

Fortification definition

Fortification requirements in milk, skim milk and alternative beverages

Answer 4

Systematic preventive action lead by the Federal Government meant to correct identified nutrient deficiencies in the population
- Can be mandatory or voluntary

Milk must have vitamin D fortification
Skim milk must have A and D fortification
Plant beverages can have B12, B2, Ca and Zn

Question 5

Soy as an alternate milk

How to make homemade soy milk

Answer 5

Soy beverage is only equivalent for cow’s milk in terms of protein and micronutrients

1) Grind soy beans in hot water to inactive lipoxygenase (prevents bitter taste)
2) Boil for 20 min to inactivate trypsin inhibitor (can also be bitter)

Question 6

Highest and lowest protein levels in milks and beverages

Highest lactose content

Highest mineral content

Answer 6

Highest: fin whales (12g/100g) –> goat/cow (3.4g/100g) –> zebu (3.3g) –> Soy enriched (2.9) –> human (1.1g) –> almond (.63g)

Human then Cow milk

Fin whale —> cow and goat

Question 7

Does milk cause cancer?

Is milk full of growth hormones?

Answer 7

No evidence that it does, might even reduce risk of bowel cancer

Artificial growth hormones have been banned in Canada since 1999, it is illegal to even sell in Canada

Question 8

Fat content

Answer 8

High milk fat milk can be used to make cream and butter (more expensive)
- produced by cows in winter

Fat is in globules composed of phospholipids and proteins which stabilize unstable emulsion
- high temp tolerance but not to freezing (pierces globules)

Question 9

Milk sensitivities

Answer 9

Milk allergy - allergy to milk protein

Lactose intolerance - insufficient production of lactase enzyme

B-Casein intolerance - A1 and A2 proteins
- A2 protein is tolerated better than A1
- can be confused for lactose intolerance

Question 10

Lactose content in human milk

Lactase

Lactose fermenting bacteria

Answer 10

Provides nearly 50% of calories in human milk

Lactase enzyme can convert lactose into galactose + glucose

Lactobacilli and lactococci consume lactose and convert it to lactic acid which sours milk but prevents spoilage from harmful bacteria

Question 11

Casein types and percentages

Answer 11

Primary protein in milk, 80% of total protein

Clumps and precipitates out with acids or enzymes

48% a-casein
20% B-casein
16% k-casein
2% y-casein

Question 12

Whey types and percentages

Components of whey

Answer 12

Influences texture of casein curds and stabilizes milk foam

Whey is 93% water, lactose and whey protein

18% of total protein:
9% lactoglobulin
5% lactalbumin
2% immunoglobulin
2% serum albumin

Question 13

Casein stability in milk

Answer 13

Casein and whey are separate in milk but stable

Casein forms micelles that contain most Ca content

k-casein prevents clumping of micelles under stable conditions

Question 14

Color compounds in milk (milk, cream, nonfat milk)

B2 sensitivity

Answer 14

Contributors to milk’s opaque color: casein, B2, colloidal casein-Ca micelle

Cream and butter yellowish color: carotene from cow feed and B2

Nonfat milk has a blueish hue

B2 is sensitive to UV light - opaque packaging

Question 15

Notable nutrients in milk

Notable nutrients missing

Answer 15

Vitamins: A, D, B2
AA: Tryptophan
Minerals: Ca (major), P, K, Mg, Na, Cl, S

Low vitamin C and E

Question 16

Types of pasteurization

Answer 16

High temperature short time (HTST)
- heat to 72°C for 16 seconds minimum
- rapid cool to 4°C

Batch-holding:
- heat to 62° C
- hold at 62°C for 30 minutes
- cool rapidly to 4° C

Ultra-high temperature (UHT)
- whole or partly skimmed milk heated to 138-158° C for 1-2 seconds
- Cooled rapidly and placed under sterile conditions into sterilized containers

Question 17

Homogenization process

Benefits of homogenization

Negatives of

Answer 17

Milk is unstable emulsion - will separate into fat cream on top and no fat milk on the bottom

Homogenization: high pressure force through a filter which breaks fat globules into smaller ones

Benefits of homogenization:
1) Increases creaminess, whiteness and blandness of flavor
2) Coagulates better

Negatives:
1) increases vulnerability to rancidity - with addition of O2 to fatty acid double bonds