Milk a secretion of the mammary gland for the nourishment of the young. The amount of food value in milk varies from animal to animal and from region to region. The amount also varies according to nature of fodders of animals.
Cow milk and milk products form an important component of human diet. Children must have it for growth and health. Adults require it for health and invalids as well as old people must have it to prolong their longevity.
Milk from cows consists of water, organic substances, and mineral salts. Average composition of milk is 87.6 percent water, 3.7 percent fat, 3.2 percent protein, 4.8 percent lactose and 0.72 percent ash. Whole milk is an excellent source of calcium, phosphorus, riboflavin, protein and vitamin A. One hundred ml of milk may furnish 65.3 calories. Total milk production in Bangladesh, however, is much lower than the national demand. Hence a considerable quantity of milk powder is imported. Local milk consumption in liquid form in 1993-94 was 4,62,000 metric tons. This includes milk from cows, buffalo and goats. The milk product made from imported milk was about 19,000 metric tons. A large part of the available milk is used to make different types of milk products.
Liquid milk may be consumed as skim milk, that is to say, milk from which sufficient milk-fat has been removed to reduce its fat content to below 0.50 per cent. It is however, rich in water-soluble vitamins and minerals. Skim milk is not widely used in Bangladesh.
In several cities pasteurized milk is available. Pasteurization is done by heating the milk to at least 63BAC and holding it continuously at or above this temperature for at least 30 minutes, or to at least 72BAC, and holding it continuously at or above this temperature for at least 15 seconds, to ensure the destruction of all pathogenic microorganisms. This is followed by immediate cooling of the milk to 4.4BAC or less. Most milk is consumed in Bangladesh by boiling it for not less than 20 minutes.
Often 'toned milk' is made by adding water and non-fat dry milk to fresh whole milk. Whole buffalo milk is usually admixed with reconstituted spray dried skim milk from production. It should contain 1.0 to 3.0 percent fat and 8.5 to 10.5 percent solids to make 11.5 percent total solids. Such milk is useful for low-income groups. [AKM Abdul Mannan]