Milk carbohydrates

• Lactose is a milk sugar varies from 4.7 to 4.9% in the milk.
• Lactose has the molecular formula same as the sucrose, C 12 H 22 O 11 but it differs from sucrose in following aspects:

a) Lactose is less sweet than the sucrose, i.e., 6 times less sweet.

b) It is less soluble but more reactive than sucrose.

Sweeting value of sucrose:- 100%

Sweeting value of glucose:- 74%

Sweeting value of galactose:-  32%

Sweeting value of lactose:- 16%

c) Lactose is easily decomposed by bacteria to form lactic acids in milk which gives the milk sour taste.

d) It is slightly soluble in ethyl alcohol and other alcohol but insoluble in ether, chloroform, benzene, etc.

e) It absorbs odour and flavour very quickly.

• The average lactose content of milk varies between 4.7 and 4.9%, though milk from individual cows may vary more.
• Mastitis reduces lactose secretion.
• In cheese-making lactose remains in the whey fraction.
• Lactose can be sprayed on silage to increase the rate of acid development in silage fermentation.