Milk

Thousands of years ago, a chance mutation spread in human populations in northwestern Europe that enabled the production of lactase in adulthood.

[20] Lactase, the enzyme needed to digest lactose, reaches its highest levels in the human small intestine immediately after birth, and then begins a slow decline unless milk is consumed regularly.

[22] Humans first learned to consume the milk of other mammals regularly following the domestication of animals during the Neolithic Revolution or the development of agriculture.

[27] Sherratt's model is not supported by recent findings, based on the analysis of lipid residue in prehistoric pottery, that shows that dairying was practiced in the early phases of agriculture in Southwest Asia, by at least the seventh millennium BC.

Milk consumption became common in these regions comparatively recently, as a consequence of European colonialism and political domination over much of the world in the last 500 years.

Urban demand began to grow, as consumer purchasing power increased and milk became regarded as a required daily commodity.

[78] FAO reports[52] Israel dairy farms are the most productive in the world, with a yield of 12,546 kilograms (27,659 lb) milk per cow per year.

[80] The IPCC Sixth Assessment Report mentions the possibility that the already recorded stagnation of dairy production in both China and West Africa can be attributed to persistent increases in heat stress caused by climate change.

[88] Milk is an emulsion or colloid of butterfat globules within a water-based fluid that contains dissolved carbohydrates and protein aggregates with minerals.

These kappa-casein molecules all have a negative electrical charge and therefore repel each other, keeping the micelles separated under normal conditions and in a stable colloidal suspension in the water-based surrounding fluid.

The first theory, attributed to de Kruif and Holt, proposes that nanoclusters of calcium phosphate and the phosphopeptide fraction of beta-casein are the centerpiece to micellar structure.

Under the second theory, proposed by Horne, the growth of calcium phosphate nanoclusters begins the process of micelle formation, but is limited by binding phosphopeptide loop regions of the caseins.

The fat globules contain some yellow-orange carotene, enough in some breeds (such as Guernsey and Jersey cattle) to impart a golden or "creamy" hue to a glass of milk.

Pasteurization is used to kill harmful pathogenic bacteria such as M. paratuberculosis and E. coli 0157:H7 by heating the milk for a short time and then immediately cooling it.

[99] The standard high temperature short time (HTST) process of 72 °C (162 °F) for 15 seconds completely kills pathogenic bacteria in milk,[100] rendering it safe to drink for up to three weeks if continually refrigerated.

[123][124] People affected vary in the amount of lactose they can tolerate before symptoms develop,[123] which may include abdominal pain, bloating, diarrhea, gas, and nausea.

[123] Those affected are usually able to drink at least one cup of milk without developing significant symptoms, with greater amounts tolerated if drunk with a meal or throughout the day.

Lactose-reduced milk can also be produced via ultra filtration, which removes smaller molecules such as lactose and water while leaving calcium and proteins behind.

Some nutritionists have criticized flavored milk for adding sugar, usually in the form of high-fructose corn syrup, to the diets of children who are already commonly obese in the US.

With time, due to the steadily increasing cost of collecting, transporting, storing and cleaning glass bottles, they were replaced by cardboard cartons.

Another significant and popular addition to the marketplace has been flavored milks; for example, as mentioned above, Farmers Union Iced Coffee outsells Coca-Cola in South Australia.

[148] In rural India, milk is home delivered, daily, by local milkmen carrying bulk quantities in a metal container, usually on a bicycle.

[149] Although India is the world's largest milk producer and a major exporter, the country's ever-increasing demand for dairy products could eventually make it a net importer.

The reduced pH from lactic acid accumulation denatures proteins and causes the milk to undergo a variety of different transformations in appearance and texture, ranging from an aggregate to smooth consistency.

Pasteurization of cow's milk initially destroys any potential pathogens and increases the shelf life,[157][158] but eventually results in spoilage that makes it unsuitable for consumption.

[160][161] In another version of the story, Athena, the patron goddess of heroes, tricked Hera into suckling Heracles voluntarily,[160][161] but he bit her nipple so hard that she flung him away, spraying milk everywhere.

Its soft blandness served as inspiration for the name of the timid and ineffectual comic strip character Caspar Milquetoast, drawn by H. T. Webster from 1924 to 1952.

Diluted milk solutions have been demonstrated to provide an effective method of preventing powdery mildew on grape vines, while showing it is unlikely to harm the plant.

[173] Cosmetic chemist Ginger King states that milk can "help exfoliate and remove debris [from skin] and make hair softer.

Seagulls, sheathbills, skuas, western gulls and feral cats have been reported to directly pilfer milk from the elephant seals' teats.