HOME WEB NEWS IMAGES CLASSIFIEDS YELLOW PAGESPOLLS - SURVEYS WIKI COUNTRIES PHOTOS US UK INDIA
Cities Stocks Weather Movies Coupons Travel Blogs Health Horoscope Maps ASIA EUROPE Classifieds Yellow Pages
|
 5
|
For other uses, see Milk (disambiguation).
|
|
This article needs additional citations for verification. Please help improve this article by adding reliable references. Unsourced material may be challenged and removed. (November 2007) |
A glass of pasteurized cow milk.
Milk is an opaque white liquid produced by the mammary glands of female mammals (including monotremes). 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.
Contents |
There are two distinct types of milk consumption: a natural source of nutrition for all infant mammals; and a food product for humans of all ages derived from other animals.
A goat kid feeding on its mother\'s milk.
In almost all mammals, milk is fed to infants through breastfeeding, either directly or, for humans, by expressing the milk to be stored and consumed later. Some cultures, historically or currently, continue to use breast milk to feed their children until as old as seven years.. . . or just go with the flow?. The Times, May 5, 2005.
In many cultures of the world, especially the Western world, humans continue to consume milk beyond infancy, using the milk of other animals (in particular, cows) as a food product. For millennia, cow 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.
| Top Ten Milk Consumers — 2006 Per Capita Consumption | |||
|---|---|---|---|
| Country | Liters | Cheese (kg) | Butter(kg) |
 Finland | 183.9 | 19.1 | 5.3 |
 Sweden | 145.5 | 18.5 | 1.0 |
 Ireland | 129.8 | 10.5 | 2.9 |
 Netherlands | 122.9 | 20.4 | 3.3 |
 Norway | 116.7 | 16.0 | 4.3 |
 Spain | 119.1 | 9.6 | 1.0 |
 Switzerland | 112.5 | 22.2 | 5.6 |
 United Kingdom | 111.2 | 12.2 | 3.7 |
 Australia | 106.3 | 11.7 | 3.7 |
 Canada | 94.7 | 12.2 | 3.3 |
| Source: Introduction to Dairy Science and Technology: Milk History, Consumption, Production, and Composition | |||
Humans are an exception in the natural world for consuming milk past infancy. Even those humans who drink milk after eating solid foods are uncommon within the whole of humanity. Most humans lose the ability to fully digest milk after childhood (that is, they become lactose intolerant). The sugar lactose is found only in milk, forsythia flowers, and a few tropical shrubs. The enzyme needed to digest lactose, lactase, reaches its highest levels in the small intestines after birth and then begins a slow decline unless milk is consumed regularly. McGee, Harold (1984). "Milk and Dairy Products", On Food and Cooking: The Science and Lore of the Kitchen (in English). New York: Charles Scribner\'s Sons, 3-53. ISBN 0-684-18132-0. 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 cows, but also sheep, goats, yaks, water buffalo, horses, and camels.
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.
Holstein cattle, the dominant breed in industrialized dairying today.
Milking has its advent in the very evolution of placental mammals. While the exact time of its appearance is not known, the immediate ancestors of modern mammals were much like monotremes, 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, marsupials, 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. Cow milk was first used as human food in the Middle East. Goats and sheep were domesticated in the Middle East between 9000 and 8000 BC[citation needed]. Goats and sheep are ruminants: mammals adapted to survive on a diet of dry grass, a food source otherwise useless to humans, and one that is easily stockpiled. The animals were probably first kept for meat and hides[citation needed], but dairying proved to be a more efficient way of turning uncultivated grasslands into sustenance: the food value of an animal killed for meat 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.[citation needed]
Milk was first delivered in bottles on January 11, 1878. The day is now remembered as Milk Day and is celebrated annually. The town of Harvard, Illinois also celebrates milk in the summer with a festival known as Milk Days. Theirs is a different tradition meant to celebrate dairy farmers in the "Milk Capital of the World."http://www.milkdays.com/
Goat milk can be used for other applications such as cheese and other dairy products.
In addition to cows, the following animals provide milk used by humans for dairy products:
In Russia and Sweden, small moose dairies also exist."Moose milk makes for unusual cheese", The Globe and Mail, 26 June 2004. Retrieved on 2007-08-27. Donkey and horse milk have the lowest fat content, while the milk of seals contains more than 50% fat.Milk From Cows and Other Animals, web page by Washington Dairy Products Commission
Whale milk, not used for human consumption, is one of the highest-fat milks, containing up to 50% fat.MSN encarta livescience.com The high fat content of whale milk is not a product of cetacean\'s great size, as guinea pig milk has an average fat content of 46%.Morales, Edmundo (1995). The Guinea Pig : Healing, Food, and Ritual in the Andes. University of Arizona Press. ISBN 0-8165-1558-1.
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.
| Top Ten Milk Producers — 2005 (1000 tonnes) | |
|---|---|
 India | 91,940 |
 United States | 80,264 |
 China | 32,179 |
 Russia | 31,144 |
 Pakistan | 29,672 |
 Germany | 28,487 |
 France | 26,133 |
 Brazil | 23,455 |
| United Kingdom | 14,577 |
 New Zealand | 14,500 |
| World Total | 372,353 |
| Source: UN Food & Agriculture Organisation | |
In the Western world today, cow 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 StatesFAO Food outlook: International dairy product prices are turning down: how far, how fast? FAO online publication, 1 June 2006 and China. In India, Amul, a cooperative owned jointly by 2.6 million small farmers was the engine behind the success of Operation Flood.[citation needed]
| Top Ten Buffalow Milk Producers — 2005 | ||||
|---|---|---|---|---|
| Country | Production (Int $1000) | Footnote | Production (MT) | Footnote |
| India | 25,344,630 | C | 50,740,000 | F |
| Pakistan | 9,840,150 | C | 19,700,000 | |
| People\'s Republic of China | 1,373,625 | C | 2,750,000 | F |
 Egypt | 1,148,850 | C | 2,300,000 | F |
 Nepal | 446,848 | C | 894,591 | |
 Iran | 117,382 | C | 235,000 | F |
 Italy | 83,441 | C | 167,050 | F |
 Myanmar | 61,938 | C | 124,000 | F |
 Turkey | 23,976 | C | 48,000 | F |
 Vietnam | 15,484 | C | 31,000 | F |
| No symbol = official figure,F = FAO estimate, * = Unofficial figure, C = Calculated figure; Production in Int $1000 have been calculated based on 1999-2001 international prices | ||||
| Top Ten Cow Milk Producers — 2005 | ||||
|---|---|---|---|---|
| Country | Production (Int $1000) | Footnote | Production (MT) | Footnote |
| United States | 21,315,090 | C | 80,150,000 | |
| India | 10,238,690 | C | 38,500,000 | * |
| Russia | 8,137,764 | C | 30,600,000 | * |
 Greece | 7,339,944 | C | 27,600,000 | F |
| France | 6,723,495 | C | 25,282,000 | * |
| People\'s Republic of China | 6,435,748 | C | 24,530,080 | F |
| Brazil | 6,201,721 | C | 23,320,000 | F |
| New Zealand | 3,889,372 | C | 14,625,000 | * |
| United Kingdom | 3,876,608 | C | 14,577,000 | |
 Ukraine | 3,586,068 | C | 13,484,500 | * |
| No symbol = official figure,F = FAO estimate, * = Unofficial figure, C = Calculated figure; Production in Int $1000 have been calculated based on 1999-2001 international prices | ||||
| Top Ten Goat Milk Producers — 2005 | ||||
|---|---|---|---|---|
| Country | Production (Int $1000) | Footnote | Production (MT) | Footnote |
| India | 813,888 | C | 2,700,000 | * |
 Bangladesh | 426,839 | C | 1,416,000 | F |
 Sudan | 390,365 | C | 1,295,000 | F |
| Pakistan | 198,950 | C | 660,000 | |
| France | 176,945 | C | 587,000 | |
| Greece | 149,213 | C | 495,000 | F |
| Spain | 40,170 | C | 465,000 | F |
| Iran | 110,026 | C | 365,000 | F |
| Ukraine | 87,418 | C | 290,000 | * |
| Russia | 78,073 | C | 259,000 | * |
| No symbol = official figure,F = FAO estimate, * = Unofficial figure, C = Calculated figure; Production in Int $1000 have been calculated based on 1999-2001 international prices | ||||
It was reported in 2007 that with increased world-wide prosperity and the competition of biofuel production for feedstocks, both the demand for and the price of milk had substantially increased world wide. Particularly notable was the rapid increase of consumption of milk in China and the rise of the price of milk in the United States above the government subsidized price."A Thirst for Milk Bred by New Wealth Sends Prices Soaring" article by Wayne Arnold in the New York Times September 4, 2007
Schematic of a micelle.
Milk is an emulsion or colloid of butterfat globules within a water-based fluid. Each fat globule is surrounded by a membrane consisting of phospholipids and proteins; these emulsifiers 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 milk, the fat globules average about four micrometers 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 casein protein micelles: aggregates of several thousand protein molecules, bonded with the help of nanometer-scale particles of calcium phosphate. Each micelle is roughly spherical and about a tenth of a micrometer across. There are four different types of casein proteins, and collectively they make up around 80 percent of the protein in milk, by weight. Most of the casein proteins are bound into the micelles. There are several competing theories regarding the precise structure of the micelles, but they share one important feature: the outermost layer consists of strands of one type of protein, kappa-casein, 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 colloidal suspension in the water-based surrounding fluidDairy Chemistry and Physics, webpage of University of Guelph (McGee 19–20).
A simplified representation of a lactose molecule being broken down into glucose and galactose.
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
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 cells. Mammary-gland cells, various bacteria, and a large number of active enzymes are some other components in milk (McGee 16).
Milk products and productions relationships (Click for details)
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 is used to kill 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 dates 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.
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 an even longer lasting sterilization process.
A milking machine in action.
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 homogenized, a treatment which prevents a cream layer from separating out of the milk. The milk is pumped at high pressures through very narrow tubes, breaking up the fat globules through turbulence and cavitation.Homogenization of Milk and Milk Products, webpage of University of Guelph A greater number of smaller particles possess more total surface area 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 enzymes 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. Unlike pasteurization, homogenization confers no health or safety benefits to the milk, only the convenience of not needing to shake the bottle oneself.[citation needed]
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 globules 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:
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.
| Cow milk (whole) Nutritional value per 100 g (3.5 oz) |
|||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Energy 60 kcal 250 kJ | |||||||||||||||||||||||||||||
| |||||||||||||||||||||||||||||
| 100 ml corresponds to 103 g.Jones, Alicia Noelle (2002). Density of Milk. The Physics Factbook. Percentages are relative to US recommendations for adults. Source: USDA Nutrient database |
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 grams of protein, and a number of other nutrients (either naturally or through fortification):
The amount of calcium from milk that is absorbed by the human body is disputed.Calcium Rich Foods: Get All The Calcium You Need Without MilkFeskanich D, Willett WC, Stampfer MJ, Colditz GA. Milk, dietary calcium, and bone fractures in women: a 12-year prospective study. Am J Public Health 1997; 87:992-7. Calcium from dairy products has a greater bioavailability than calcium from certain vegetables, such a spinach, that contain high levels of calcium-chelating agents. Brody T. Calcium and phosphate. In: Nutritional biochemistry. 2nd ed. Boston: Academic Press, 1999:761–94
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 One 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.Fat ice cream and milk may help woman shoot for pregnancy - Pravda.Ru Milk is a source of Conjugated linoleic acid, a fatty acid that inhibits several types of cancer in mice. It has been shown to kill human skin cancer, colorectal cancer and breast cancer cells in vitro studies, and may help lower cholesterol and prevent atherosclerosis; only available in milk from grass-fed cows.
Other studies suggest that milk consumption may increase the risk of suffering from certain health problems. Milk contains casein, a substance that breaks down in the human stomach to produce casomorphin, an opioid peptide. In the early 1990s it was hypothesized that casomorphin can cause or aggravate autism,Reichelt KL, Knivsberg A-M, Lind G, Nødland M (1991). "Probable etiology and possible treatment of childhood autism". Brain Dysfunct 4: 308–19. Christison GW, Ivany K (2006). "Elimination diets in autism spectrum disorders: any wheat amidst the chaff?". J Dev Behav Pediatr 27 (2 Suppl 2): S162–71. PMID 16685183. and casein-free diets are widely promoted. Studies supporting these claims have had significant flaws, and the data are inadequate to guide autism treatment recommendations.Christison GW, Ivany K (2006). "Elimination diets in autism spectrum disorders: any wheat amidst the chaff?". J Dev Behav Pediatr 27 (2 Suppl 2): S162–71. PMID 16685183. Cow milk allergy (CMA) is as an immunologically mediated adverse reaction to one or more cow milk proteins. Rarely is it severe enough to cause death.[2] One study demonstrated that men, and to some degree women, who drink a large amount of milk and consume dairy products were at a slightly increased risk of developing Parkinson\'s disease.H. Chen et al., Consumption of Dairy Products and Risk of Parkinson\'s Disease, American Journal of Epidemiology. 2007 May;165(9):998-1006 The reason behind this is not fully understood, and it also remains unclear why there is less of a risk for women.H. Chen et al., Consumption of Dairy Products and Risk of Parkinson\'s Disease, American Journal of Epidemiology. 2007 May;165(9):998-1006"Milk linked to Parkinson\'s risk", BBC News. Several sources suggest a correlation between high calcium intake (2000 mg per day, or twice the US recommended daily allowance, equivalent to six or more glasses of milk per day) and prostate cancer.Giovannucci, E. et al., Calcium and fructose intake in relation to risk of prostate cancer., Cancer Res. 1998 Feb 1;58(3):442-7. A large study specifically implicates dairy.Chan, J.M., Dairy products, calcium, and prostate cancer risk in the Physicians\' Health Study. Am J Clin Nutr. 2001 Oct;74(4):549-54. (disputed publication) A review published by the World Cancer Research Fund and the American Institute for Cancer Research states that at least eleven human population studies have linked excessive dairy product consumption and prostate cancer,The World Cancer Research Fund and American Institute for Cancer Research (1997). "Food, nutrition and the prevention of cancer: a global perspective". Food, nutrition and the prevention of cancer: a global perspective. however randomized clinical trial data with appropriate controls only exists for calcium, not dairy produce, where there was no correlation.Chan JM et al., (2005) Role of diet in prostate cancer development and progression. J Clin Oncol 23:8152-60. Medical studies have also shown a possible link between milk consumption and the exacerbation of diseases such as Crohn’s Disease,How Bacteria In Cows\' Milk May Cause Crohn\'s Disease Hirschsprung\'s disease–mimicking symptoms in babies with existing cow milk allergies,Cow milk protein allergy presenting with Hirschsprung\'s disease–mimicking symptoms. severe gastroesophageal reflux disease in infants and children hypersenstitive to milk,[citation needed] and the aggravation of Behçet\'s disease.Humoral and cell mediated immune response to cow\'s milk proteins in Behçet\'s disease
Since November 1993, with FDA approval, Monsanto has been selling recombinant bovine somatotropin (rbST)--or rBGH--to dairy farmers. Additional bovine growth hormone is administered to cattle in order to increase their milk production, though the hormone also naturally fosters liver production of insulin-like growth factor 1 (IGF1). The deposit thereof in the milk of rBGH-affected cattle has been the source of concern; however, all milk contains IGF1 since all milking cows produce bovine growth hormone naturally. The IGF1 in milk from rBGH-affected cattle does not vary from the range normally found in a non-supplemented cow.IDFA - Biotechnology and Bovine Somatotropin (BST or BGH) Elevated levels of IGF1 in human blood has been linked to increased rates of breast, colon, and prostate cancer by stimulating their growth,Kahan, Z et al., Elevated levels of circulating insulin-like growth factor-I, IGF-binding globulin-3 and testosterone predict hormone-dependent breast cancer in postmenopausal women: a case-control study. Int J Oncol. 2006 Jul;29(1):193-200.Pacher, M. et al., Impact of constitutive IGF1/IGF2 stimulation on the transcriptional program of human breast cancer cells. Carcinogenesis. 2006 Jun 14 though this has not been linked to milk consumption. The EU has recommended against Monsanto milk.International Scientific Committee Warns of Serious Risks of Breast and Prostate Cancer from Monsanto\'s Hormonal Milk. Press release of the Cancer Prevention Coalition. In addition, the cows receiving rBGH supplements may more frequently contract an udder infection known as mastitis.Milk: Epstein, S., America\'s Health Problem. Web page of the Cancer Prevention Coalition. Milk from rBGH-affected cattle is banned in Canada, Australia, New Zealand, and Japan due to the mastitis problems. On June 9, 2006 the largest milk processor in the world and the two largest supermarkets in the United States--Dean Foods, Wal-Mart, and Kroger--announced that they are "on a nationwide search for rBGH-free milk."[3] No study has indicated that consumption of rBST-produced milk increases IGF1 levels, nor has any study demonstrated an increased risk of any disease between those consuming rBST and non-rBST produced milk. In 1994, the FDA stated that no significant difference has been shown between milk derived from rBST-treated and non-rBST-treated cows, and that no test exists which can differentiate between milk from rBST-treated and non-rBST treated cows.Dietary IGF-I and rbST
Milk may contain varying levels of white blood cells depending upon the health of the source animals, according to guidelines set up by the Food and Drug Administration and statistics reported by the dairy industry.http://www.ag.ndsu.edu/pubs/ansci/dairy/as1131w.htmGreger, Michael. Paratuberculosis and Crohn\'s Disease: Got Milk? Pro-vegan online publication, January 2001 Although not considered a human health issue by most authorities, elevated white blood cell levels indicate an immune response by cattle, due in part to mastitis.http://www.ag.ndsu.edu/pubs/ansci/dairy/as1131w.htm There are concerns regarding the transmission of bovine paratubeculosis through somatic cells to humans,http://www.veganoutreach.org/health/gotmilk.html but the evidence is largely inconclusive.
Lactose, the disaccharide sugar component of all milk must be cleaved in the small intestine by the enzyme lactase in order for its constituents (galactose and glucose) to be absorbed. The production of this enzyme declines significantly after weaning in all mammals including humans[citation needed] (except for most northern westerners and a few other ethnic groups, lactase decline occurs after weaning, sometime between the ages of two and five). Once lactase levels have decreased sufficiently, consumption of small amounts of lactose can cause diarrhea, intestinal gas, cramps and bloating, as the undigested lactose travels through the gastrointestinal tract and serves as nourishment for intestinal microflora who excrete gas. http://en.wikipedia.orgAnaerobic_respiration
Milk Composition Analysis, per 100 grams
| Constituents | unit | Cow | Goat | Sheep | Water Buffalo |
|---|---|---|---|---|---|
| Water | g | 87.8 | 88.9 | 83.0 | 81.1 |
| Protein | g | 3.2 | 3.1 | 5.4 | 4.5 |
| Fat | g | 3.9 | 3.5 | 6.0 | 8.0 |
| Carbohydrate | g | 4.8 | 4.4 | 5.1 | 4.9 |
| Energy | kcal | 66 | 60 | 95 | 110 |
| kJ | 275 | 253 | 396 | 463 | |
| Sugars (Lactose) | g | 4.8 | 4.4 | 5.1 | 4.9 |
| Fatty Acids: | |||||
| Saturated | g | 2.4 | 2.3 | 3.8 | 4.2 |
| Mono-unsaturated | g | 1.1 | 0.8 | 1.5 | 1.7 |
| Polyunsaturated | g | 0.1 | 0.1 | 0.3 | 0.2 |
| Cholesterol | mg | 14 | 10 | 11 | 8 |
| Calcium | IU | 120 | 100 | 170 | 195 |
Source: McCane, Widdowson, Scherz, Kloos.[4]
These compositions vary by breed, animal, and point in the lactation period. Jersey cows produce milk of about 5.2% fat, Zebu cows produce milk of about 4.7% fat, Brown Swiss cows produce milk of about 4.0% fat, and Holstein-Friesian cows produce milk of about 3.6% fat. The protein range for these four breeds is 3.3% to 3.9%, while the lactose range is 4.7% to 4.9%. McGee, Harold (2004). On Food and Cooking: The Science and Lore of the Kitchen, Completely Revised and Updated. New York, NY: Scribner, 13. ISBN 9780684800011.
Milk fat percentages in all dairy breeds vary according to digestible fibre, starch and oil intakeshttp://www.kt.iger.bbsrc.ac.uk/FACT%20sheet%20PDF%20files/kt21.pdf, and can therefore be manipulated by dairy farmers\' diet formulation strategies. Mastitis infection can cause fat levels to decline.Google Books - Designing Foods: Animal Product Options in the Marketplace
Milk products are sold in a number of varieties based on types/degrees of
Cow milk is generally available in several varieties according to approximate butterfat content (using United States terminology):
In Canada "whole" milk refers to creamline (unhomogenized) milk. "Homogenized" milk refers to milk which is 3.25% butterfat. Generally all store-bought milk in Canada has been homogenized. Yet, the term is also used as a name to describe butterfat content for a specific variety of milk. Modern commercial dairy processing techniques involve first removing all of the butterfat, and then adding back the appropriate amount depending on which product is being produced on that particular line.
In Britain, it is possible to get Channel Island milk, which is 5.5% fat.
In the United States, skim milk is also known as "fat free" milk, due to USDA regulations stating that any food with less than ½ gram of fat per serving can be labeled "fat free".
Full cream, or whole milk, has the full milk fat content (about 3-4% if Friesian- or Holstein-breed are the source). For skimmed or semi-skimmed milk, all of the fat content is removed and then some (in the case of semi-skimmed milk) is returned. The best-selling variety of milk is semi-skimmed; in some countries full-cream (whole) milk is generally seen as less healthy and skimmed milk is often thought to lack taste. Whole milk is recommended to provide sufficient fat for developing toddlers who have graduated from breast milk or infant formula.
In the United States and Canada, a blended mixture of half cream and half milk is often sold in small quantities and is called half-and-half. Half-and-half is used for creaming coffee and similar uses. In Canada, low-fat cream is available, which has half the fat content of half-and-half.
Organic Milk (in the United States) or Bio-Milk & Biologique Milk (in Europe) is milk produced without the use of chemical herbicides or pesticides, and generally with more natural fertilizers and higher standards for the animals[citation needed], and is now easy to find on the shelves in many areas. Demeter certified milk is produced with Biodynamic agriculture methods and is similar in standards to organic milk and biological milk, with a few special farm procedures added that are biodynamic-specific.
In countries where the cattle (and often the people) live indoors, commercially sold milk commonly has vitamin D added to it to make up for lack of exposure to UVB radiation.
Reduced fat milks often have added vitamin A to compensate for the loss of the vitamin during fat removal; in the United States this results in reduced fat milks having a higher vitamin A content than whole milk. "How to Buy Dairy Products", Home and Garden Bulletin 255, USDA, February 1995. Retrieved 16 May 2007.
To aid digestion in those with lactose intolerance, milk is available in some areas with added bacterial cultures such as Lactobacillus acidophilus ("acidophilus milk") and bifidobacteria ("a/B milk")."Yogurt and Other Cultured Dairy Products", National Dairy Council, 2000. Another milk with Lactococcus lactis bacteria cultures ("cultured buttermilk") is often used in cooking to replace the traditional use of naturally soured milk, which has become rare due to the ubiquity of pasteurization which kills the naturally occurring lactococcus bacteria.Rombauer, Irma S. and Marion Rombauer Becker (1975). Joy of Cooking (Revised Edition). Bobbs Merrill, 533. ISBN 0-672-51831-7.
Milk often has flavoring added to it for better taste or as a means of improving sales. Chocolate flavored milk has been sold for many years and has been followed more recently by such other flavors as strawberry and banana.
South Australia has the highest consumption of flavored milk per person in the world, where Farmers Union Iced Coffee outsells Coca-Cola, a success shared only by Inca Kola in Peru and Irn-Bru in Scotland.
Switzerland has a soft drink based on milk that tastes and looks much like SevenUp. This popular "milk-cola", named Rivella, is in fact the national soft drink and even comes complete in low calorie & low sugar varieties. In spite of what might be expected, it does not taste like milk.
Because milk spoils so easily, it should, ideally, be distributed as quickly as possible. In many countries milk used to be delivered to households daily, but economic pressure has made milk delivery much less popular, and in many areas daily delivery is no longer available. People buy it chilled at grocery or convenience stores or similar retail outlets. Prior to the widespread use of plastics, milk was sold in wax-coated paper containers; prior to that milk was often distributed to consumers in glass bottles; and before glass bottles, in bulk that was ladled into the customer\'s container.
Glass milk bottles used for home delivery service
In the UK, milk can be delivered daily by a milkman who travels his local milk round (route) using a battery-powered milk float during the early hours. Milk is delivered in 1 pint glass bottles with aluminium foil tops. Silver top denotes full cream unhomogenized; red top full cream homogenized; red/silver top semi-skimmed; blue/silver check top skimmed; and gold top channel island.
Empty bottles are rinsed before being left outside for the milkman to collect and take back to the dairy for washing and reuse. Currently many milkmen operate franchises as opposed to being employed by the dairy and payment is made at regular intervals, by leaving a check; by cash collection; or direct debit.
Although there was a steep decline in doorstep delivery sales throughout the 1990s, the service is still prominent, as dairies have diversified and the service is becoming more popular again. The doorstep delivery of milk is seen as part of the UK\'s heritage, and is relied upon by people up and down the country.
In New Zealand, milk is no longer distributed in glass bottles. In rural India, milk is delivered daily by a local milkman carrying bulk quantities in a metal container, usually on a bicycle; and in other parts of metropolitan India, milk is usually bought or delivered in a plastic bags or cartons via-shops or supermarkets.
In the United States bottles were replaced with milk cartons, which are tall paper boxes with a square cross-section and a peaked top that can be folded outward upon opening to form a spout. Now milk is increasingly sold in plastic bottles. First the gallon and half-gallon sizes were sold in plastic jugs while the smaller sizes were sold in milk cartons. Recently milk has been sold in smaller resealable bottles made to fit in automobile cup holders.
The half-pint milk carton is the traditional unit as a component of school lunches. In the U.S., pictures of missing children were printed on the larger milk cartons as a public service until it was determined that this was disturbing to children.
Milk preserved by the UHT process is sold in cartons often called a brick that lack the peak of the traditional milk carton. Milk preserved in this fashion does not need to be refrigerated before opening and has a longer shelf life than milk in ordinary packaging. It is more typically sold unrefrigerated on the shelves in Europe than in America.
Glass milk containers are now rare. Most people purchase milk in bags, plastic jugs or waxed-paper cartons. Ultraviolet light from fluorescent lighting can destroy some of the proteins in milk[citation needed] so many companies that once distributed milk in transparent or highly translucent containers are now using thicker materials that block the UV light. Many people feel that such "UV protected" milk tastes better[citation needed].
Milk comes in a variety of containers with local variants:
