Lactalis Group : milk, raw material


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Milk, raw material

A complete feedingstuff

Milk, noble matter

Words of milk,
the glossary

Milk has many components. Chemical analysis of milk has revealed that it contains an exceptional diversity of ions and molecules that, far from being a random mass of substances, are arranged in an ordered mix.The slightest change in milk's temperature or acidity modifies this initial balance and enables milk to be turned into other dairy products.

A journey into the centre of a drop of milk

Water molecules are in constant motion : salts, proteins and fats are dispersed in the water in milk as particles, whose size varies from that of a tiny metal ion to a globule of fat Caught up in the water's incessant movement, ions and molecules of different kinds, soluble proteins and casein micelles swirl about in a disorganised fashion, going first one way then suddenly changing direction.

Water

Water, which makes up 80% of a person's body mass, is also the main ingredient in milk, comprising 905g of every litre of milk. Water brings oxygen and nutrients to all parts of the body, via the blood. It also enables the kidneys to filter out waste and is used to control body temperature.
The water molecules roll and slide against each other, at speeds of several hundred metres per second. They collide with and pick up an unimaginable diversity and number of ions and molecules, endlessly sweeping them into a zigzagging route.
They also push the casein micelles in various directions. These are between 30 and 300 times larger than lactose molecules and never collide because they repel each other. Globules of fat 100, 1,000 or 10,000 times bigger than the casein particles are also present in the turbulence.
They are far too big to be knocked off course by the water molecules, and they gently rise to the surface of the milk, joining together to form huge bunches of fat.

Proteins

These are chains of amino acids with differing structures and components. Caseins suspended in water, and soluble whey proteins can easily be distinguished in milk.

- Caseins:
Caseins account for most of the proteins in milk, but they do not form a homogenous group.There are various categories that differ in terms of their amino acid composition.
They tend to gather in aggregates of hundreds if not thousands of molecules : it is casein micelles that give milk its white colour. These macromolecules are rich in mineral salts, particularly calcium, and repel each other due to their negative electrical charge.
If the acid level in milk increases, the casein micelles become unstable and join together to form a casein network : this is what happens when the milk curdles.

- Whey proteins:
These proteins are resistant to a slight increase in the acid levels of their environment and they also differ from caseins in terms of their composition and sensitivity to heat, which alters their nature and structure. Some caseins (immunoglobulins) act as antibodies : antibacterial substances present in milk.

Glucids

Milk contains the glucid lactose, also known as 'milk sugar'. There are 49g of lactose in one litre of milk, the equivalent of 12 sugar cubes (lactose is6 times less sweet than beet sugar, known as saccharose). In the intestines, lactose boosts the production of bacteria that counter the microbes that cause disease. It also contributes to the absorption of calcium.

Fat

The fat in milk is an extremely complex mixture of different molecules. It consists essentially of triglycerides, formed by the association of three fatty acids and glycerol alcohol.
There are more than 150 different fatty acids in milk. The fat in milk is insoluble in water and so forms an emulsion which looks like a mass of spherical droplets. Each of them is a mass of fat surrounded by a membrane.
These droplets are lighter than water and so gently rise to the surface of the milk, clustering together with other droplets they meet during their ascent. This natural but reversible separation creates the cream we see on milk, a mixture of skimmed milk and pure fat.

fat

Mineral salts

Milk contains a total of some 9g of minerals, made up of 1.3g calcium, 1g phosphorus, 1.6g potassium, 1.1g chlorine, 0.5g sodium and .14g magnesium.
Milk is the best source of calcium for bone and tooth development because it contains the ideal proportions of phosphorus and vitamin D required to absorb calcium into the body.

Vitamins

Milk contains two categories of vitamin:
- Hydrosoluble vitamins that dissolve in water and whey (vitamins B and C)
- Liposoluble vitamins that dissolve in fat and cream (vitamins A,D and E : skimmed milk has no liposoluble vitamins). Milk contains almost all the vitamins needed for life, with the exception of vitamin C, which comes from fruit and vegetables. Milk does not contain iron either : this can be compensated for by simply adding a small amount of cocoa powder to your milk, for example.

vitamins

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