Milk ontiene about 87% water.
3.5% fat-droplets finely divided 1-10 microns in
diameter - gives opacity. When milk comes to rest for a
long time, some of the fat accumulates on the surface to
form the cream.
Nearly 4% are protids (organic
substances containing nitrogen) between casein
predominates. Less important are the lacto-albumin (albumin
from milk) and lacto-giobulina. When milk is acidified,
is "short" means giving prótidos clot semisolid lumps.
4.5% lactose (milk sugar) dissolved in water,
communicates the sweet taste.
Inorganic salts are rare: 0.5%
finally, in low proportion, and fulfill biological
functions, are vitamins A and D, the latter instrumental
in setting calcium phosphate on teeth and bones.
The chemical composition depends on the breed of cattle,
the time of year (winter is richer in fat) and the time
and milking interval.
A composition as diverse, with fat, protein and
carbohydrates, determines that milk is a very complete
food. A child should drink at least half a liter a day.