Biochemical composition of milk

The mammary gland is one of the most important organs in the body of females of all mammals. This gland synthesizes milk, which is the only food for their babies in the early stages of postnatal development. The mammary gland in animals is often called an udder. The udder of the cow consists of four separate glands. Each gland is divided into lobes (they have 5-20 cows), each part is lobed. The main structural and functional unit of the gland is the alveolus, which is enveloped in a dense network of capillaries. Milk is a polydisperse system consisting of true and colloidal solutions, suspensions and emulsions. Cow's milk is a white liquid with a yellowish tint, sweet to taste and with a peculiar smell.

Milk is synthesized in the alveoli, in part - in small and medium excretory ducts. The formed secret enters the large excretory ducts, after which it accumulates in the milk tank. Then transported to the teat canal and released into the external environment. The mammary gland functions in the lactation period, the duration of which is about 300 days.

Milk is one of the main food products for humans and animals. It consists of proteins, lipids, carbohydrates. Proteins of cow's milk are absorbed by 96-99%, lipids - by 95, carbohydrates - by 98%.

For nutrition people often use milk from cows, less - goats, mares, camels, buffalo, deer, zebu and yak.

Chemical composition of milk

In milk contains about two hundred individual substances. These compounds can be divided into five main fractions: salts, water, carbohydrates, lipids, proteins. In milk, water can be in two states: free and bound. When thickening, drying and other types of treatment, free water is easily removed. Bound water is part of the solvate shells of polydisperse systems. In fresh milk, the concentration of bound water is about 3.5%, in the low-fat to 2.6%.

Protein composition of milk. The concentration of proteins in cow's milk can reach up to 4%. Low-fat milk contains mainly alpha- casein. In milk, it forms a caseinate-calcium phosphate complex, which participates in the formation of a shell of lipid balls; Α-lactalbumin is thermostable, participates in the biosynthesis of milk sugar (lactose) from monosaccharides (galactose, glucose); Β-lactoglobulin denatures in a neutral medium (pH = 7) and when heated to 70 ° C.

Milk globulins are characterized by high molecular weight (up to 1 million Da), the structure of their molecule includes a carbohydrate component, they exhibit the properties of enzymes (lipoxidases). Non-protein nitrogenous compounds in milk are urea and, to a lesser extent, amino acids, purine bases and creatine.

Carbohydrate composition of milk. In general, carbohydrates of milk are lactose (an average of 4.7%), monosaccharides (glucose, galactose), aminosugars and phosphoric esters monoz. The highest concentration of lactose is registered in rhinoceros milk.

Lipid composition of milk. The composition of milk fat includes triacylglycerols, sterols, sterols, phospholipids and glycolipids. Their concentration in the milk of animals depends on various factors (lactation period, breed, diet, etc.). In milk fat, there are many residues of stearic, palmitic, myristic and oleic acids.

Vitamin composition of milk. Cow milk contains a sufficient amount of both fat (A, D, E) and water-soluble (PP, B1, B2, C) vitamins. To increase the concentration of vitamins in milk, animals are fed a variety of foods that are rich in vitamins, and also vitamin A, B or E concentrates are added to the diet. Milk contains pigments: carotenes, lactoflavins and chlorophylls, the color of milk depends on their concentration.

One of the drawbacks of dry milk is that it is rather difficult to restore it to a liquid state. This product has been produced for more than 110 years, however, the biochemical composition of dry milk differs from its natural state, so natural milk is much more useful.