The milk is a Boisson of color generally blanchâtre produced by the Mammifère S Femelle S (including the Monotrèmes). This capacity of the females is one of the characteristics defining the mammals. Milk is produced by the cells Sécrétrice S of the glands contained in the Mamelle S. the milk secreted in the first days after the Parturition is called the Colostrum.

The function first of milk is Nourrir the Progéniture until it is separated, i.e. able to digest other food. In the majority of the human Civilization S, the milk of the domestic mammals (Cow, ewe, Goat, mare, dri, chamelle, Dromedary, bufflonne) is usually consumed.

By analogy, one also uses the term of milk to indicate several drinks of consistency and/or appearance similar and produced containing plants, like the Lait of soya, of coconut, rice , almond , oats or pistachio .

History

Lactation is a phenomenon which occurred during the evolution of the placental mammals. The exact time of its appearance remains unknown, but the immediate ancestors of modern mammals resembled much the Monotrème S, including the Ornithorynque. These animals secrete today a substance similar to milk starting from glands which are on the surface of their skin, but they are deprived of the nipple which makes it possible their offspring to drink after the blossoming of their eggs. In the same way the marsupial , the cousins closest to the placental mammals, secrete a substance similar to milk starting from a body resembling a nipple in their pockets. The first known immediate ancestor of the placental mammals seems to be Eomaia, a small creature which resembled superficially the Rongeur S and which one thinks that she lived there are 125 My, during the Crétacé. It is almost certain that it produced what would be regarded as milk, in the same way that the modern placental mammals.

It is known that the milk of the animals was used in the human consumption as soon as they started to be domesticated. It is the cow's milk of which one was used oneself initially for the the Middle East. Goats and sheep were domesticated during; it is about Ruminantia , i.e. mammals which adapted to survive thanks to a dry grass mode, an useless to human and easily stored source of food. It is probable that one started to keep these animals for their meat and their skin, but to raise them for their milk proved to be a more effective manner to transform uncultivated pastures into food; in addition the food value of an animal killed for its meat can be counterbalanced by the milk value produced by this same animal, which will continue to provide some - and daily - during years.

With, there were herds of cattle in certain parts of current Turkey. One has evidence that one consumed milk in British Isles with the Neolithic . The use of Cheese and Beurre was spread in Europe and in some parts of Asia and Africa. The domestic cows, which existed already in most of Eurasia, were then introduced into the colonies of Europe at the time of great explorations.

Physical and chemical composition

Milk is a liquid Blanc chechmate, slightly viscous, of which the composition and the physicochemical characteristics vary appreciably according to the animal Espèce S, and even according to the Race S. These characteristics also vary during the period of Lactation, like during the Traite.

The cow's milk has a average Densité equalizes to 1,032. It is a very complex and very unstable mixture. It contains a strong proportion of water, approximately 87%. The remainder constitutes the dry Extrait which represents 130 G per liter, including 35 to 45 G of fat contents. The other principal components are the organic components (glucids Lactose, lipids, protids, vitamins), the mineral components (Ca, Na, K, Mg, Cl) and water. Milk contains the various groups of nutrients. The organic substances (glucid, lipid, protid) are present in about equal quantity and release all from energy. These nutrients are divided into elements builders, the protids and in energy elements, the glucids and the lipids. Milk contains also functional elements, mineral ions (Ca, P, K, Na, Mg,…), vitamins and water.

On the physical level, it is at the same time a solution (lactose, rock salt), a suspension (nitrogenized matters) and a emulsion (fat contents).

Its pH is slightly Acide (pH ranging between 6,4 and 6,8 for the cow's milk). It is slightly basic for human milk with a pH ranging between 7 and 7,5. The acidity of milk increases with time. Indeed, the lactose will be degraded in Lactic acid, which will make it possible to have an indicator of the degree of conservation. For that, one uses the Degré Dornic (°D).

It is also a biological environment: it contains blood cells and mammaires (until 30  000 per ml) and of the Microbe S (until 50  000 per ml) .

The mare and ass's milks are those which contain less fat contents, whereas that of seal contains some more than 50%. Generally, the milk of the marine mammals is much richer in greases and nutrients that of the terrestrial mammals.

Principal protein of milk

The Caséine is the most abundant Protéine of milk. It is a complex Polypeptide, result of the polycondensation different amino-acid, whose principal ones are the Leucine, the Proline, the Glutamic acid and Sérine.

The Phosphore is fixed there in the form of Phosphate S. the Calcium joins phosphate and casein for given the complex phosphocaséinate of calcium and form a Colloïde. One also finds Magnésium there, potassium and sodium but it is, at least for the cow's milk, low in oligoélément. Milk is among the animal liquid biological, one of those which contain the greatest citric concentration of Acid, it is an anticoagulant and he is opposed to precipitation proteins.

The concentration in lipid varies from 10 to 500 g/l according to the species. They are primarily made up (99%) of Triglycéride S.

The principal sugar of milk is the Lactose, whose sweetening capacity is six times weaker than that of the Saccharose. It can cause some intolerance.

The proteinic Micelle S have a diameter of about 0,1 μm. All in all, there are more carboxyl groups than of groups amines, this explains why milk is naturally acid (6,6 < pH < 6,8).

Consumption

See also: Milk industry, Cow's milk, Dairy product

Milk is generally regarded as a very complete food from the nutritional point of view. It contains indeed almost all the Vitamine S (except notable for the Vitamine C and, for the Skimmed milk, of the vitamins has and D). The dairy fat contents are however rich in saturated fatty-acids. To nourish the human babies, one uses a particular mechanism named Tire-lait. The milk of human origin is not produced nor not distributed on an industrial scale. There exist however milk banks (Lactarium) which make it possible to collect the gifts of mother's milk and to redistribute it with the children which needs some (premature, allergic,…).

Milk that the man milked near many species of animals is conditioned or transformed into Dairy product for human consumption. This harvest can be done by artisanal or industrial techniques. The Cow's milk is principal milk used.

The animals mainly used for the food production of milk are:

  • Sheep
  • Goat
  • Horse
  • ass
  • Camel (and others Camélidés)
  • Yak
  • Buffalo
  • Reindeer
  • dash

Controversies

A growing number of scientific studies consider the Cow's milk as a food which could be harmful for the human being: according to them, its proteins and its calcium would be with difficulty comparable by the mankind, because adapted to small calf only.

The Asian populations consume few dairy products without apparent consequences for health. Japan holds the world records of longevity: 84 years for the women, 77 years for the men and especially of the life expectancy in good health 73 years on average. The Japanese island of Okinawa, lodging an exceptional number of centenaries, has in particular several times been the subject of scientific studies and works declining their mode vegetarian without milk. It is necessary however to moderate these results by taking of account the whole formed by the food (contributions of unsaturated fatty-acids resulting from a mode containing fatty fish,…) and lifestyle of these Japanese citizens.

Studies call into question the cow's milk and its benefits against the osteoporosis. American professor T. Colin Campbell (American researcher in nutrition at the university of Cornell, New York) affirmed that the dairy produces do not protect from the osteoporosis. Dr. Roland Weinsnier and Carlos Krumdiek, of the University of Alabama to Birmingham, in the number of September 2000 of the " American Newspaper off Clinical Nutrition" also establish that the studies " do not allow to support the recommendation which aims at encouraging the dairy produce consumption to support the health of the os."

Moreover, certain authors (see the work of T.Souccar which reviews various studies) think that the casein of milk, its calcium as certain hormones which it contains could in makes contribute to emergence certain grave diseases (diabetes of the type I in the child, multiple sclerosis, cancers and even the osteoporosis that milk is supposed to prevent).

See too

In Kitchen, one calls Eggflip a Boisson prepared by watering an Egg yolk of hen in milk glass. The Confiture of milk is a receipt Norman. The Cake with three milks, Rice pudding is desserts.

Regulation

In France, at the lawful level, " the denomination " lait" without indication of the animal specie of source, is reserved for the cow's milk. Any milk coming from a dairy female other that the cow must be indicated by the denomination " lait" followed indication of the animal specie from which it comes: " milk of chèvre" , " milk of brebis" , " milk of ânesse" , etc cf.

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External bonds

  • Qualitionnaire - legal and normative Definitions - milk
  • Methods and risks of transfer of the persistent organic pollutants towards milk

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