Milk is considered nature's most perfect food because it contains almost all the substances essential for human nutrition. Although milk and milk products are specially intended to nourish young, nutritionist generally include dairy foods to balance the diets of humans of all ages. Several kinds of mammal are raised to produce milk for human consumption. Of these, dairy cattle are of greatest commercial importance, but milk is also obtained from water buffalo, goats, sheep, camels, reindeer, mares, and other mammals.
Factors that affect the composition of cow's milk:
- Breed of cow has the greatest bearing
- Time between milking
- Season of year
- Feeds or food of the cow
- Age and its overall health
Nutrients in Milk: Milk is considered a rich source of calcium, phosphorus, and riboflavin (vitamin B2); a good source of high quality protein, vitamins A, B1 (thiamin), and B12 (cobalamine); but a poor source of iron, copper, manganese, nicotinic acid, and vitamins C and D.
Composition of Milk: Milk is composed of milk fat, lactose (milk sugar), protein, minerals, and water. The nonfat portion of milk is called skim milk, even when not separated from whole milk. Colostrums is the first milk from the mammal after bearing young, it has a much higher constituent (except lactose or milk sugar) than the succeeding milk. Colostrums also contain the immune globulin, the carriers of antibodies to protect the young from infectious diseases.
a. Milk fat. Milk fat consists of triglycerides containing at least 52 kinds of fatty acids. Approximately 67% of the fatty acids in milk fat are saturated, while 33% are unsaturated.
b. Proteins. Milk protein is complete in that it contains all eight essential amino acids in the correct amounts. Milks protein has two major components; casein which is the most abundant protein in milk. It forms a thin film on the enamel surface which prevents loss of calcium and phosphate from the enamel when the teeth are exposed to acids in the mouth. Whey proteins are lactalbumin and lactoglobulin, and are similar to the blood proteins, albumin and globin.
c. Lactose. The principal sugar of milk, lactose is found in milk of nearly all mammals and in no other natural foods.
d. Minerals. Milk contains significant quantities of all of the minerals essential for human nutrition except copper, iron, and manganese.
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