The major constituent of milk is water, but milk contains varying levels of lipids, proteins, and carbohydrates which are synthesized within with mammal gland. Their composition is influenced by animal species, environmental conditions, nutrition of animals, their lactation state and others.
Lactose is the principal carbohydrate found in milk. It is virtually unique to milk, having been found elsewhere only in fruits of certain members of the Sapotaceae. Lactose is consumed through milk and other unfermented dairy products, such as ice cream.
Disaccharides lactose in milk imparts sweet profile and human milk has a major concentration of lactose (7.4%) compared to milk of other species. The main role of lactose includes:
*It provides galactose for the synthesis of the nerve structures of the growing infant
*In the intestine, it gets metabolized to lactic acid which eliminates harmful bacteria.
Lactase is a membrane-bound enzyme located in the brush border epithelial cells of the small intestine. Once lactose reaching the small intestine, where the hydrolytic enzyme lactase (β-galactosidase) is located, lactase catalyzes the hydrolysis of lactose into its constituent monosaccharides (glucose and galactose). Only monosaccharides among the carbohydrates are absorbed from the intestines.
Lactose accounts for ~30% of the caloric value of whole milk. Lactose is an important energy source and sometimes it is referred to simply as milk sugar, as it is present in high percentages in milk. Lactose-intolerance individuals have a lactase deficiency; therefore, lactose is not completely catabolized.
Milk lactose – main roles in human body
