Lecture 3

Question 1

What is milk

Answer 1

Lacteal secretion free from colostrum. that has been either pasteurized or ultra-pasteurized.

Should contain at least 8.25% milk solids and 3.25% milk fat.

Question 2

Classification of grade A milk (for human consumption)

Answer 2

Cooled to below 7 degrees
Bacterial limit: <300,000/ml
No drug residues
Somatic cell count < 750,000/ml

Question 3

Properties of milk

Answer 3

1. Oil-in-water emulsion (fat globules dispersed in the continuous serum phase)
2. Colloidal suspension (of casein micelles, globular proteins and lipoproteins)
3. Solution of lactose, soluble proteins, minerals, vitamins

Question 4

Components of milk fractions

Answer 4

Total solids = milk solids + solid (non-fat)

Solids (non-fat) = proteins + minerals + vitamins + lactose + enzymes + acids

Plasma = milk - fat

Serum = plasma - casein micelles = milk - fat - casein micelles

Question 5

Nutritional composition of cow milk

Answer 5

%water = 87
%solids = 13 (of which 3% protein)

Question 6

Proportion of casein vs whey of cow’s milk

Answer 6

80% casein
20% whey

Question 7

Components of whey protein in cow’s milk

Answer 7

50% beta-lactoglobulin
20% alpha-lactalbumin

Question 8

Proportion of casein vs whey of human’s milk

Answer 8

40% casein
60% whey

Question 9

Components of whey protein in human’s milk

Answer 9

0% beta-lactoglobulin
100% alpha-lactalbumin

Question 10

Does human milk contain alpha casein?

Answer 10

No

Question 11

Function of alpha casein s1 protein

Answer 11

sensitive to calcium (calcium binding)
It is a cofactor for lactose formation.

Question 12

What is colostrum

Answer 12

Colostrum is the first form of breastmilk that is released by the mammary glands after giving birth. It’s nutrient-dense and high in antibodies and antioxidants to build a newborn baby’s immune system. It changes to breast milk within two to four days after your baby is born.