Minerals in milk

Minerals represent a small portion of milk (about 8-9 g/L) and they occur in different chemical forms: inorganic ions and salts or as parts of proteins, nucleic acids, fats and carbohydrates. Minerals are constituents of the bones, teeth, soft tissue, muscle, blood, and nerve cells. They are vital to overall mental and physical well-being.

When milk is dried and the residue is burned, a white powder is obtained which is known as ash or mineral part of the milk. The major portion of ash is composed of the chlorides and oxides of potassium, calcium and phosphorus. It is of interest to note that these three elements are in greater concentration in milk than in blood, thus the mammary gland exerts a selective action to concentrate these elements.

The mineral content in milk is influenced by many factors ranging from environmental conditions during pasture, feeding, breeding, stage of lactation and climate to post-milking handling, transportation and processing.

The chemical form of mineral elements found in milk and dairy products is very important due to their absorption in the intestine and biological utilization (transport, assimilation in cells and conversion into biologically active form).

Milk contains more calcium than most foods because of the distribution of calcium in milk. About two thirds of the total calcium in milk is in colloidal form as calcium caseinate, citrate and phosphate; the remaining third is in true solution.

Phosphorus in milk is involved in the stabilization of caseins and is present in two forms: organic and inorganic. Organic P is bound to molecules such as proteins, organic acids, phospholipids and nucleotides, mainly in colloidal phase, and inorganic ionic P is mainly present in soluble fraction.
Minerals in milk

Lipid content in milk

Milk is the liquid food secreted by the mammary gland for the nourishment of the newly born, containing water, fat, protein, lactose and minerals.

Bovine milk contains about 3.5 to 5% total lipid, existing as emulsified globules 2 to 4 μm in diameter and coated with a membrane derived from the secreting cell.

The lipid content of mammalian milk varies from 16 g/liter (horse) to 105 g/liter (deer), human milk contains about 38 g of fat per liter.

The lipids consist essentially of triglycerides, together with very small proportions of other lipids including phospholipids, cholesterol, squalene, lanosterol, free fatty acids, traces of monoglycerides resulting from lipolysis, and bound aldehydes, glycerol ethers, and also keto-compounds,

Triacylglycerols make up 98% of the lipid content of milk, ranging in different species from 0 to 50% of the total milk volume. The fatty acid composition of the triacylglycerols depends on the species, the dietary fatty acid composition, and the carbohydrate-to-lipid ratio of the diet.

Phospholipids or ‘lipids containing phosphorus’ are about 0.5 to 1% of total lipids, and· sterols are 0.2 to 0.5%. These are mostly located in the globule membrane. Cholesterol is the major sterol at 10 to 20 mg/dl.
Lipid content in milk

Lactose In Milk

Milk is an emulsion produced by mammary glands which characterize with white color, mild taste and flavor.

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.
Lactose In Milk

Vitamins content of dairy milk

Vitamins are organic chemicals required by the body in trace amounts but which cannot be synthesized by the body.

The vitamins found in milk include vitamins A, D, E and K, ascorbic acid, thiamin, riboflavin, niacin, panthotenic acid, pyridoxine, folic acid, and cyanocobalamin.

Fat-soluble vitamins A, D, E and K are located in the milk fat component of milk. Cow’s milk is generally well pigmented with carotene, the precursor of vitamin A. About 11% to 50% of total vitamin A activity in milk is derived from carotenoids, the specific proportion depending on the breed and feed of the cow and season of year, among other factors.

Ruminant derived all the water soluble vitamins via synthesis by rumen microbial flora, but are dependent on an exogenous supply of the fat soluble vitamins.

The quantities of water soluble vitamins and of vitamin K in milk are little affected by feed, season, breed or stage of lactation, whereas the quantities of vitamins D and E are influenced by feed.

Dairy milk contains more vitamin B than soy milk. It has 8 types of vitamin B, compared to soy milk which contains 7 types, but lacking in vitamin B12.

All the vitamins appear to be well absorbed from milk products and make important contributions to human diets.
Vitamins content of dairy milk

Major constituent of milk

Milk is a complex biological fluid, composition and physical characteristics of which vary from species to species, reflecting the dietary needs of the young mammal.

The major constituent of milk is water, but according to species milk contains varying quantities of lipids, proteins, and carbohydrates which are synthesized within with mammal gland.

Disaccharides lactose in milk imparts sweetness. Human milk has a major concentration of lactose (7.4%) compared to milk of other species. Milk lactose serves to major functions:
*It provides galactose, a structural unit for the growing infant
*In the intestine, it gets metabolized to lactic acid which eliminates harmful bacteria.

The lipid content of mammalian milk varies from 16 g/liter (horse) to 105 g/liter (deer), human milk contains about 38 g of fat per liter.

When milk is dried and the residue is burned, a white powder is obtained which is known as ash or mineral part of the milk. The major portion of ash is composed of the chlorides and oxides of potassium, calcium and phosphorus. It is of interest to note that these three elements are in greater concentration in milk than in blood, thus the mammary gland exerts a selective action to concentrate these elements.

Milk contains more calcium than most foods because of the distribution of calcium in milk. About two thirds of the total calcium in milk is in colloidal form as calcium caseinate, citrate and phosphate; the remaining third is in true solution.

Milk contains lot of vitamins, among them vitamin B complex is dissolved in the water and vitamins A and D in the fat. Only ascorbic (vitamin C) is present in limited amount and it may absent from pasteurized milk.
Major constituent of milk

Vitamin A in cow's milk

All-trans retinol is the main form of vitamin A present in milk, the cis isomer of retinol being sometimes observed in a very low amount in cow’s milk.

The amount of vitamin A in milk varies with the carotene content of the feed. Normally, vitamin A potency is highest when the cow is on succulent pastures in the spring and lowest when the cow is hay-fed during the winter season.

The vitamin A potency of milk can be increased to a level that approaches summer milk by feeding rations high in carotene content.

Concentrations of vitamin A and carotenoids in milk are also dependent on animal species. Indeed caprine milk is richer (30%) in retinol and conversely beta-carotene is 30% higher in cow’s milk than goat’s milk.

Guernsey milk contained more carotene than preformed vitamin A, Jersey approximately equal proportions whereas the Holstein milk the carotene constituted approximately 30 percent and the vitamin A, 70 percent of the total biological active vitamin A.
Vitamin A in cow’s milk

Goat milk nutritional value

Although the date of first milking and milk utilization is unknown, the first deliberately soured goat milk probably was prepared before 2000 BC.

Goat’s milk is used for drinking and making cheese and yoghurt.Goat milk differs from cow or human milk in higher digestibility, distinct alkalinity, higher buffering capacity and certain therapeutic values in human medicine and nutrition.

The chemical composition of goat milk varies with breed and other factors, but goat milk contains approximately 11-0-13.0 % total solids, 3.0-5.5 % fat, 2.9-4.6 % proteins, 3.8-5.1 % lactose and 0.69-0.81 % ash (mineral matter).

It is naturally homogenized, with smaller fat molecules evenly suspend throughout the milk.Fat in goat milk is high of short chain and medium chain triglycerides therefore goat milk more rapidly digested than cow milk because lipase attacks ester linkages of short or medium chain fatty acids more easily than those of longer chains.

Goat milk contains slightly less total casein but higher non-protein nitrogen than the cow counterpart.

Milk from goats is also high in vitamin A and niacin. Goats milk is one of the best fluorine sources, nearly ten times higher than cow’s milk. Dietary fluorine helps build immunity, protect teeth, and strengthen bones; however, fluorine is lost in pasteurization.

Goat milk taste varies a great deal by bred, by feed stuffs, by stage of lactation, by the age of the milk and especially by the way it’s handled.

This milk may be the milk of choice for children who are allergic to cow’s milk. The difference in the proteins mean that goat’s milk doesn’t cause an allergic response.

Goat milk nutritional value