eChapter Name: Chemical Nature of Milk
9789358875225
eBook Name: CHEMISTRY OF MILK AND MILK PRODUCTS
by Pinaki Ranjan Ray
Introduction
The mammary glands of female mammals secrete milk, a necessary food that is liquid and meets the newborn’s nutritional needs. All mammals consider milk to be a complete food for their newborns. It is considered a necessary food for humans and can be consumed as a product or as liquid milk. It contains almost all essential nutrients except iron, which is very low in milk. In essence, milk is an emulsion of protein and fat in water, supplemented with carbohydrates, vitamins, and minerals.
Definition of Milk
• Milk is a complex biological fluid that differs from species to species in both composition and physical properties. It is the full lacteal secretion of a mammary gland that is obtained by milking mammals for a minimum of 72 h after calving or until the milk is free from colostrum.
• FSSAI defines milk as the normal mammary secretion derived from the complete milking of healthy milch animals. It should be free from colostrum.
From a chemical perspective, milk is a dynamically balanced mixture that comes in different forms such as emulsion, colloidal suspension, and true solution. It also contains varying amounts of proteins, fats, carbohydrates, salts, and water.
Gross Composition of Milk
Milk composition varies among different mammals. The average chemical composition of milk in various species is given in Table 1. Buffalo milk and sheep milk contain higher amounts of fat, while human milk comparatively has the highest lactose content. Human milk has lower protein content as compared to milk of other species.