Information AboutMilk |
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's milk.]] Milk is an opaque white liquid produced by the Mammary Gland s of female Mammal s (including Monotreme s). Mammary glands are highly specialized sweat glands. The female ability to produce milk is one of the defining characteristics of mammals. It provides the primary source of nutrition for Newborns before they are able to Digest other types of food. The early Lactation milk is known as Colostrum , and carries the mother's Antibodies to the baby. It can reduce the risk of many diseases in the baby. Males of all mammal species retain the breasts that are part of the fundamental mammalian animal structure, hence their nipples. Lactation occurs in males in certain rare circumstances, both naturally and artificially, however, some pharmaceuticals precipitate lactation in males readily. The exact components of raw milk varies by species, but it contains significant amounts of Saturated Fat , Protein and Calcium as well as Vitamin C . Unfortunately the vitamin C is destroyed by the heat in pasteurization process. Humans are among the few animals who cannot manufacture this vitamin so its presence in the natural milk of their mothers is essential for the health of human infants and vitamin supplements are necessary for human infants fed only pasteurized milk. Aquatic mammals, such as Seals and Whales , produce milk that is very rich in fats and other solid nutrients when compared with land mammals' milk. Human s, as other mammals, can consume mother's milk during their infancy. Some mammals lose the ability to digest milk properly if a long period passes without consumption of it after weaning. In many Ethnic Groups , people lose the ability to digest milk after childhood (that is, they become Lactose Intolerant ), so many traditional Cuisines around the world, such as Chinese Cuisine , do not feature Dairy Products . On the other hand, those groups that do continue to tolerate milk often have exercised great creativity in using the milk of Domesticated Ruminants , not only of Cow s, but also Sheep , Goat s, Yak s, Water Buffalo , Horse s, and Camel s. For millennia, cow's milk has been processed into dairy products such as Cream , Butter , Yogurt , Ice Cream , and especially the more durable and easily transportable product, Cheese . Industrial science has brought us Casein , Whey Protein , Lactose , Condensed Milk , Powdered Milk , and many other food-additive and industrial products. , May 5 , 2005 . The term ''milk'' is also used for whitish non-animal substitutes such as Soy Milk , Rice Milk , Almond Milk , and Coconut Milk . Even the regurgitated substance Pigeons feed their young is called Crop Milk though it bears little resemblance to mammalian milk. HISTORY cattle, the dominant breed in industrialized dairying today.]] Milking has its advent in the very evolution of Placental Mammal s. While the exact time of its appearance is not known, the immediate ancestors of modern mammals were much like Monotreme s, including the Platypus . Such animals today produce a milk-like substance from glands on the surface of their skin, but without the nipple, for their offspring to drink after hatching from their eggs. Likewise, Marsupial s, the closest cousin to placental mammals, produce a milk-like substance from a teat-like organ in their pouches. The earliest immediate ancestor of placental mammals known seems to be Eomaia , a small creature superficially resembling rodents, that is thought to have lived 125 million years ago, during the Cretaceous era. It almost certainly produced what would be considered milk, in the same way as modern placental mammals. Animal milk is first known to have been used as human food at the beginning of animal domestication. can be matched by perhaps one year's worth of milk from the same animal, which will keep producing milk — in convenient daily portions — for years (McGee 8–10). Around 7000 BC, Cattle were being herded in parts of Turkey . There is evidence of milk consumption in the British Isles during the Neolithic Period . The use of Cheese and Butter spread in Europe , parts of Asia and parts of Africa . Domestic cows, which previously existed throughout much of Eurasia , were then introduced to the colonies of Europe during the Age Of Exploration . MODERN PRODUCTION See Also: Dairy farming In the Western world today, Cow 's milk is produced on an industrial scale. It is by far the most commonly consumed form of milk in the western world. Commercial Dairy Farming using Automated Milking equipment produces the vast majority of milk in developed countries. Types of Cattle such as the Holstein have been specially bred for increased milk production. According to McGee, 90% of the dairy cows in the United States and 85% in Great Britain are Holsteins (McGee 12). Other milk cows in the United States include Ayrshire , Brown Swiss , Guernsey , Jersey , and Milking Shorthorn . The largest producers of dairy products and milk today are India followed by the United States FAO Food outlook: International dairy product prices are turning down: how far, how fast? FAO online publication, 1 June 2006 and New Zealand. OTHER MILK ANIMALS In addition to Cows , the following animals provide milk used by humans for dairy products:
In Russia and Sweden , small Moose Dairies also exist.1 Donkey and horse milk have the lowest fat content, while the milk of Seal s contains more than 50% fat. Milk From Cows and Other Animals, web page by Washington Dairy Products Commission 's great size, as Guinea Pig milk has an average fat content of 46%.2 Human milk is not produced or distributed industrially or commercially; however, milk banks exist that allow for the collection of donated human milk and its redistribution to infants who may benefit from human milk for various reasons (premature neonates, babies with allergies or metabolic diseases, etc.). All other female mammals do produce milk, but are rarely or never used to produce dairy products for human consumption. PHYSICAL AND CHEMICAL STRUCTURE Milk is an Emulsion of Butterfat Globules within a water-based fluid. Each fat globule is surrounded by a membrane consisting of Phospholipids and proteins; these Emulsifier s keep the individual globules from joining together into noticeable grains of butterfat and also protect the globules from the fat-digesting activity of Enzymes found in the fluid portion of the milk. In unhomogenized cow's milk, the fat globules average about four Micrometer s across. The Fat-soluble vitamins A , D , E , and K are found within the milkfat portion of the milk (McGee 18). .]] The largest structures in the fluid portion of the milk are , reaching out from the body of the micelle into the surrounding fluid. 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 Colloid al Suspension in the water-based surrounding fluid Dairy Chemistry and Physics, webpage of University of Guelph (McGee 19–20). Both the fat globules and the smaller casein micelles, which are just large enough to deflect light, contribute to the opaque white color of milk. The fat globules contain some yellow-orange carotene, enough in some breeds — Guernsey and Jersey cows, for instance — to impart a golden or "creamy" hue to a glass of milk. The Riboflavin in the whey portion of milk has a greenish color, which can sometimes be discerned in skim milk or whey products (McGee 17). Fat-free skim milk has only the casein micelles to scatter light, and they tend to scatter shorter-wavelength blue light more than they do red, giving skim milk a bluish tint. Dairy Chemistry and Physics, webpage of University of Guelph molecule being broken down into Glucose and Galactose .]] Milk contains dozens of other types of proteins besides the caseins. They are more water-soluble than the caseins and do not form larger structures. Because these proteins remain suspended in the Whey left behind when the caseins coagulate into curds, they are collectively known as ''whey proteins''. Whey proteins make up around twenty percent of the protein in milk, by weight. Lactoglobulin is the most common whey protein by a large margin (McGee 20–21). The Carbohydrate Lactose gives milk its sweet taste and contributes about 40% of whole cow milk's calories. Lactose is a composite of two simple sugars, Glucose and Galactose . In nature, lactose is found only in milk and a small number of plants (McGee 17). Other components found in raw cow milk are living White Blood Cell s. Mammary-gland cells, various Bacteria , and a large number of active Enzyme s are some other components in milk (McGee 16). PROCESSING In most Western countries, a centralised Dairy facility processes milk and products obtained from milk ( Dairy Products ), such as Cream , Butter , and Cheese . In the United States, these dairies are usually local companies, while in the Southern Hemisphere facilities may be run by very large nationwide or trans-national corporations (such as Fonterra ). Pasteurization and raw milk Pasteurization kills many harmful Microorganisms by heating the milk for a short time and then cooling it for storage and transportation. Pasteurized milk is still perishable and must be stored cold by both suppliers and consumers. Dairies print Expiration Date s on each container, after which stores will remove any unsold milk from their shelves. In many countries it is illegal to sell milk that is not pasteurized. Unfortunately, the heating destroys the vitamin C content and light further destroys other beneficial aspects of milk, being the reason that opaque containers are recommended for storage and transportation. Milk may also be further heated to extend its shelf life through ultra-high temperature treatment ( UHT ), which allows it to be stored unrefrigerated, or even longer lasting Sterilization . Those preferring Raw Milk argue that the Pasteurization process also kills beneficial microorganisms and other important nutritional constituents. The resulting pasteurized product is said to be less digestible, be less nutritious, and turns Rancid (as opposed to Ferment ) with age. However, unpasteurized milk can harbor harmful disease-causing bacteria such as Tuberculosis , Brucellosis , Salmonella , Diphtheria , and Escherichia Coli . Raw Milk Vs. Pasteurized Milk. Reproduction from Armchair Science, London 1938. The cows must be maintained in very sanitary conditions and a watchful eye kept as to disease testing and vaccinations for this to be completely safe. Cheeses made with raw milk are regarded as safer as the milk typically had to be heated to some extent anyway to make the cheese, and this would kill many of the dangerous organisms possibly present. Creaming and homogenization Upon standing for 12 to 24 hours, fresh milk has a tendency to separate into a high-fat Cream layer on top of a larger, low-fat milk layer. The cream is often sold as a separate product with its own uses; today the separation of the cream from the milk is usually accomplished rapidly in Centrifugal cream separators. The fat globules rise to the top of a container of milk because fat is less dense than water. The smaller the globules, the more other molecular-level forces prevent this from happening. In fact, the cream rises in cow milk much more quickly than a simple model would predict: rather than isolated globules, the fat in the milk tends to form into clusters containing about a million globules, held together by a number of minor whey proteins (McGee 19). These clusters rise faster than individual globules can. The fat globules in milk from goats, sheep, and water buffalo do not form clusters so readily and are smaller to begin with; cream is very slow to separate from these milks (McGee 19). .]] Milk is often than a smaller number of larger ones, and the original fat globule membranes cannot completely cover them. Casein micelles are attracted to the newly-exposed fat surfaces; nearly one-third of the micelles in the milk end up participating in this new membrane structure. The casein weighs down the globules and interferes with the clustering that accelerated separation. The exposed fat globules are briefly vulnerable to certain Enzyme s present in milk, which could break down the fats and produce Rancid flavors. To prevent this, the enzymes are inactivated by pasteurizing the milk immediately before or during homogenization. Homogenized milk tastes blander but feels creamier in the mouth than unhomogenized; it is whiter and more resistant to developing off flavors (McGee 23). Creamline, or cream-top, milk is unhomogenized; it may or may not have been pasteurized. Some have suggested that homogenized milk is harder to digest or not as suited to some people as is unhomogenized milk. Unlike pasteurization, homogenization confers no health or safety benefits to the milk, only the convenience of not needing to shake the bottle oneself. Unhomogenized milk has made a small comeback in a few areas, such as the west coast of the United States where Straus Family Creameries , based originally out of Sonoma , sells one line of organic milk with the cream still on top in old-fashioned glass bottles. They still however pasteurize it to prevent harmful microorganisms. NUTRITION AND HEALTH The composition of milk differs widely between species. Factors such as the type of protein; the proportion of protein, fat, and sugar; the levels of various vitamins and minerals; and the size of the Butterfat Globule s and the strength of the Curd are among those than can vary. Introduction to Dairy Science and Technology, webpage of University of Guelph For example:
Nutritional benefits Processed milk began containing differing amounts of fat during the 1950s. A serving (1 cup or 250 ml) of 2%-fat milk contains 285 mg of Calcium , which represents 22% to 29% of the Daily Recommended Intake (DRI) of calcium for an adult. Depending on the age, 8 Gram s of Protein , and a number of other nutrients (either naturally or through fortification):
Studies show possible links between low-fat milk consumption and reduced risk of Arterial Hypertension , Coronary Heart Disease ,colorectal cancer and Obesity . Overweight individuals who drink milk may benefit from decreased risk of Insulin Resistance and type 2 Diabetes . Dairy's Role in Managing Blood Pressure, web page of the US National Dairy Council Interestingly, a study has shown that for women desiring to have a child, those who consume full fat dairy products may actually slightly increase their fertility, while those consuming low fat dairy products may slightly reduce their fertility due to interference with ovulation. However, studies in this area are still inconsistent. {Link without Title} Nutritional/physiological detriments
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