many that would make the milk unpalatable or
cause disease. Lactose and the lactic-acid
bacteria therefore turn milk sour, but help
prevent it from spoiling, or becoming
undrinkable.
Lactose is one-fifth as sweet as table sugar,
and only one-tenth as soluble in water (200 vs.
2,000 gm/l), so lactose crystals readily form
in such products as condensed milk and ice
cream and can give them a sandy texture.
Milk Fat
Milk fat accounts for much of the body,
nutritional value, and economic value of milk.
The milk-fat globules carry the fat-soluble
vitamins (A, D, E, K), and about half the
calories of whole milk. The higher the fat
content of milk, the more cream or butter can
be made from it, and so the higher the price it
will bring. Most cows secrete more fat in
winter, due mainly to concentrated winter