Milk and dairy products

Milk

Dairy milk is an opaque white liquid produced by the mammary glands of mammals (including monotremes). It provides the primary source of nutrition for newborn mammals 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. 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. Cow's milk has a pH ranging from 6.4 to 6.8, making it slightly acidic.

Types of consumption

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.

Nutrition for infant mammals

A goat kid feeding on its mother's milk.

In almost all mammals, milk is fed to infants through breastfeeding, either directly or 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 they are 7 years old.

Food product for humans

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, kefir, 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.

Humans are an exception in the natural world for consuming milk past infancy. 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. On the other hand, those groups that do continue to tolerate milk often have exercised great creativity in using the milk of domesticated ungulates, not only of cows, but also sheep, goats, yaks, water buffalo, horses, and camels.

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. 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, 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.

Around 7000 BC, cattle were being herded in parts of Turkey. There is evidence from DNA extraction of skeletons from the Neolithic period that people in northern Europe were missing the necessary genes to process lactase. Scientists claim it is more likely that the genetic mutation allowing the digestion of milk arose at some point after dairy farming began. The use of cheese and butter spread in Europe, parts of Asia and parts of Africa. 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.

In the Western world today, cow milk is produced on an industrial scale. 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 90% of the dairy cows in the United States and 85% in Great Britain are Holsteins. 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 and China.

It was reported in 2007 that with increased worldwide prosperity and the competition ofbiofuel 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.

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.

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.

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. Skimmed milk, however, appears slightly blue because casein micelles scatter the shorter wavelengths (blue compared to red).

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. 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.

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.

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.Mammary-gland cells, various bacteria, and a large number of active enzymes are some other components in milk.

ProcessingIn most Western countries, a centralised dairy facility processes milk and products obtained from milk (dairy products), such as cream, butter, and cheese.

Pasteurization

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.

A newer process, Ultra Pasteurization or ultra-high temperature treatment (UHT), heats the milk to a higher temperature for a shorter time. This extends its shelf life and allows the milk to be stored unrefrigerated because of the longer lasting sterilization effect.

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.

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. 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. Milk which has undergone high-pressure homogenization, sometimes labeled as "ultra-homogenized," has a longer shelf life than milk which has undergone ordinary homogenization at lower pressures. Homogenized milk may be more digestible than unhomogenized milk.

Because the fat globules in the milk are reduced in size and encapsulated into liposomes, they pass through the stomach undigested. (The liposomes are protected from the digestive acids.) Because of the tiny size of the fat globules after the milk has been homogenized, the liposomes are then able to pass into the bloodstream through the walls of the intestines, where the damage occurs. The liposomes contain the partially destroyed BXO enzyme. XO is only found in the liver, unless a person drinks homogenized milk. Then it is found in the liposomes that enter the bloodstream, where it begins to attack plasmalogen.

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 globules and the strength of the curd are among those than can vary. For example:

Human milk contains, on average, 1.1% protein, 4.2% fat, 7.0% lactose (a sugar), and supplies 72 kcal of energy per 100 grams.

Cow milk contains, on average, 3.4% protein, 3.6% fat, and 4.6% lactose, 0.7% minerals and supplies 66 kcal of energy per 100 grams. See also Nutritional value further on. Donkey and horse milk have the lowest fat content, while the milk whales can contain more than 50% fat. High fat content is not unique to aquatic animals, as guinea pig milk has an average fat content of 46%.

Nutritional value

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.Milk contains 8 grams of protein, and a number of other nutrients (either naturally or through fortification) including:

· Biotin

· Pantothenic acid

· Iodine

· Potassium

· Magnesium

· Selenium

· Thiamine

· Vitamin A

· Vitamin B12

· Riboflavin

· Vitamins D

· Vitamin K

The amount of calcium from milk that is absorbed by the human body is disputed. Calcium from dairy products has a greater bioavailability than calcium from certain vegetables, such as spinach, that contain high levels of calcium-chelating agents, but a similar or lesser bioavailability than calcium from low-oxalate vegetables such as kale, broccoli, or other vegetables in the Brassica genus.

Medical research

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 diabetes. 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.Milk is a source of Conjugated linoleic acid, a fatty acid that inhibits several types of cancer in mice. CLA 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; CLA is present only in milk from grass-fed cows.

Controversy

Other studies suggest that milk consumption may increase the risk of suffering from certain health problems. 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.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, 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. Studies described in the book The China Study note a correlation between casein intake and the promotion of cancer cell growth when exposed to carcinogens. However other studies have shown whey protein offers a protective effect against colon cancer.

A study demonstrated that men who drink a large amount of milk and consume dairy products were at a slightly increased risk of developing Parkinson's disease; the effect for women was smaller. The reason behind this is not fully understood, and it also remains unclear why there is less of a risk for women. 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. 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, however randomized clinical trial data with appropriate controls only exists for calcium, not dairy produce, where there was no correlation. Medical studies have also shown a possible link between milk consumption and the exacerbation of diseases such as Crohn's Disease.

Lactose intolerance

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. Consequently, many humans become unable to properly digest lactose as they mature. There is a great deal of variance, with some individuals reacting badly to even small amounts of lactose, some able to consume moderate quantities, and some able to consume large quantities of milk and other dairy products without problems. When an individual consumes milk without producing sufficient lactase, they may suffer 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, a process known as anaerobic respiration.

Lactose intolerance is a natural process and there is no reliable way to prevent or reverse it. Lactase is readily available in pill form, and many individuals can use it to briefly increase their tolerance for dairy products.

Ethical concerns

Vegans and some vegetarians do not consume milk for a variety of reasons. They may object to the treatment of cattle or to separating the mother and calf, veal production, and slaughter of "used" cows. 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%. Milk fat percentages in all dairy breeds vary according to digestible fiber and starch.

Varieties and brands

Milk products are sold in a number of varieties based on types/degrees of

age (e.g., cheddar):

· additives (e.g., vitamins),

· coagulation (e.g., cottage cheese),

· farming method (e.g., organic, grass-fed).

· fat content (e.g., half and half),

· fermentation (e.g., buttermilk),

· flavoring (e.g., chocolate),

· homogenization (e.g., raw milk),

· mammal (e.g., cow, goat, sheep),

· packaging (e.g., bottle),

· sterilization (e.g., pasteurization),

· water content (e.g., dry milk),

Organic milk (in the United States) or bio-milk and 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.

Additives and flavoring

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.

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"). 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.

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.

Distribution This section does not cite any references or sources. Please help improve this article by adding citations to reliable sources (ideally, using inline citations).

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.

In the UK, milk can be delivered daily by a milkman who travels his local milk round (route) using a milk float (often battery powered) 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.

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.

In Australia and New Zealand, milk is no longer distributed in glass bottles, due to declining sales and the introduction of long life packaging (UHT). Milk is generally sold in plastic 2 and 3 liter bottles and cardboard cartons as well as the long life varieties.

In rural India and Pakistan, 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 and Pakistan, milk is usually bought or delivered in a plastic bags or cartons via-shops or supermarkets.

In the United States, glass milk bottles have been mostly replaced with milk cartons (tall paper boxes with a square cross-section and a peaked top that can be folded outward upon opening to form a spout) and plastic jugs. Gallons of milk are almost always sold in jugs, while half-gallons and quarts may be found in both paper cartons and plastic jugs, and smaller sizes are almost always in cartons.

Spoilage and fermented milk products

When raw milk is left standing for a while, it turns "sour". This is the result of fermentation, where lactic acid bacteria ferment the lactose inside the milk into lactic acid. Prolonged fermentation may render the milk unpleasant to consume. This fermentation process is exploited by the introduction of bacterial cultures (e.g. Lactobacilli sp., Streptococcus sp., Leuconostoc sp., etc) to produce a variety of fermented milk products. The reduced pH from lactic acid accumulation denatures proteins and caused the milk to undergo a variety of different transformations in appearance and texture, ranging from an aggregate to smooth consistency. Some of these products include sour cream, yoghurt, cheese, buttermilk, viili, kefir and kumis. See Dairy product for more information.

Pasteurization of cow milk initially destroys any potential pathogens and increases the shelf-life, but eventually results in spoilage that makes it unsuitable for consumption. This causes it to assume an unpleasant odor, and the milk is deemed non-consumable due to unpleasant taste and an increased risk of food poisoning. In raw milk, the presence of lactic acid-producing bacteria, under suitable conditions, ferments the lactose present to lactic acid. The increasing acidity in turn prevents the growth of other organisms, or slows their growth significantly. During pasteurization however, these lactic acid bacteria are mostly destroyed.

In order to prevent spoilage, milk can be kept refrigerated and stored between 1 and 4 degrees Celsius in bulk tanks. Most milk is pasteurized by heating briefly and then refrigerated to allow transport from factory farms to local markets. The spoilage of milk can be forestalled by using ultra-high temperature (UHT) treatment; milk so treated can be stored unrefrigerated for several months until opened. Sterilized milk, which is heated for a much longer period of time, will last even longer, but also loses more nutrients and assume a different taste. Condensed milk, made by removing most of the water, can be stored in cans for many years, unrefrigerated, as can evaporated milk. The most durable form of milk is milk powder, which is produced from milk by removing almost all water.

Language and culture

The importance of milk in human culture is attested to by the numerous expressions embedded in our languages, for example "the milk of human kindness". In ancient Greek mythology, the goddess Hera spilled her breast milk after refusing to feed Heracles, resulting in the Milky Way.

In African and Asian developing nations, butter is traditionally made from fermented milk rather than cream. It can take several hours of churning to produce workable butter grains from fermented milk. Holy books have also mentioned milk; the Bible contains references to the Land of Milk and Honey. The verb, "to milk" something is often used in the vernacular of many English-speaking.

The word milk has had many slang meanings over time. In the early 17th century the word was used to mean semen. In the 19th century, milk was used to describe a cheap alcoholic drink made from methylated spirits mixed with water. The word was also used to mean defraud, to be idle, to intercept telegrams addressed to someone else, and a weakling. In the mid 1930s, the word was used in Australia meaning to siphon gas from a car.

Other uses of milk

Besides serving as a beverage or source of food, milk is used by farmers and gardeners as an organic fungicide and foliage fertilizer. The potassium, fats, and salts naturally found in milk are absorbed by the leaves, which boost the plant's immune system, helping it to fight off diseases and fungi. Farmers, especially those who maintain grape vineyards, have tested a diluted milk solution in the past, and have found it to be more effective, yet less costly, than commercial products. Testing has also shown that it is unlikely to harm the plant that the solution is applied to.

Dairy product

Dairy products are generally defined as foodstuffs produced from milk. They are usually high-energy-yielding food products. A production plant for such processing is called a dairy or a dairy factory. Raw milk for processing generally comes from cows, but occasionally from other mammals such as goats, sheep, water buffalo, yaks, or horses. Dairy products are commonly found in European, Middle Eastern and Indian cuisine, whereas they are almost unknown in East Asian cuisine.

Types of dairy products

· Crиme fraоche - slightly fermented cream

· Smetana - variety of sour cream

· Kefir - fermented milk drink resembling buttermilk but based on different yeast and bacteria culture

· Milk powder (or powdered milk), produced by removing the water from milk

· Whole milk and buttermilk

· Cream

· High milk-fat andnutritional powders (for infant formulas)

· Cultured and confectionery powders

· Condensed milk - milk which has been concentrated by evaporation, often with sugar

· Infant formula - dried milk powder with specific additives for feeding human infants

· Baked milk - a variety of boiled milk that has been particularly popular in Russia

· Butter - mostly milk fat, produced by churning cream

· Buttermilk - the liquid left over after producing butter from cream, often dried as livestock food

· Ghee -clarified butter, by gentle heating of butter and removal of the solid matter

· Cheese - produced by coagulating milk, separating from whey

· Quark

· Cream cheese, produced by the addition of cream to milk

· Casein

· Yogurt - milk fermented by Streptococcus salivarius ssp. thermophilus and Lactobacillus delbrueckii ssp. bulgaricus sometimes with additional bacteria, such as Lactobacillus acidophilus

· Ayran

· Gelat -slowly frozen milk and water, lesser fat than ice cream

· Ice cream - slowly frozen cream and emulsifying additives

· Ice milk

· Frozen custard

· Frozen yogurt - yogurt with emulsifiers that is frozen

Ice cream

Ice cream or ice-cream (originally iced cream) is a frozen dessert usually made from dairy products, such as milk and cream, combined with fruits or other ingredients. Most varieties contain sugar, although some are made with other sweeteners. In some cases, artificial flavorings and colorings are used in addition to (or in replacement of) the natural ingredients. This mixture is stirred slowly while cooling to prevent large ice crystals from forming; the result is a smoothly textured ice cream.

The meaning of the term ice cream varies from one country to another. There are frozen custard, frozen yogurt, sorbet, gelato and others.

Alternatives made from soy milk, rice milk, and goat milk are available to those who are unable to enjoy traditional ice cream due to lactose intolerance or allergy to dairy protein.

Production

Making ice cream was quite laborious. Ice was cut from lakes and ponds during the winter and stored in large heaps, in holes in the ground, or in wood-frame ice houses, insulated by straw. Many farmers and plantation owners, including U.S. Presidents George Washington and Thomas Jefferson, cut and stored ice in the winter for use in the summer. Frederic Tudor of Boston turned ice harvesting and shipping into big business, cutting ice in New England and shipping it around the world.

Ice cream was made by hand in a large bowl placed inside a tub filled with ice and salt. This was called the pot-freezer method. French confectioners refined the pot-freezer method, making ice cream in a sorbtierre (a covered pail with a handle attached to the lid). In the pot-freezer method, the temperature of the ingredients is reduced by the mixture of crushed ice and salt. The salt water is cooled by the ice, and the action of the salt on the ice causes it to (partially) melt.

The hand-cranked churn, which also uses ice and salt for cooling, replaced the pot-freezer method. The exact origin of the hand-cranked freezer is unknown, but the first U.S. patent for one was #3254 issued to Nancy Johnson on September 9, 1843. The hand-cranked churn produced smoother ice cream than the pot freezer and did it quicker. Many inventors patented improvements on Johnson's design.

In Europe and early America, ice cream was made and sold by small businesses, mostly confectioners and caterers. Jacob Fussell of Baltimore, Maryland was the first to manufacture ice cream on a large scale. Fussell bought fresh dairy products from farmers in York County, Pennsylvania, and sold them in Baltimore. An unstable demand for his dairy products often left him with a surplus of cream, which he made into ice cream. He built his first ice cream factory in Seven Valleys, Pennsylvania, in 1851. Two years later, he moved his factory to Baltimore. Later, he opened factories in several other cities and taught the business to others, who operated their own plants. Mass production reduced the cost of ice cream and added to its popularity.

The development of industrial refrigeration by German engineer Carl von Linde during the 1870s eliminated the need to cut and store natural ice and when the continuous-process freezer was perfected in 1926, it allowed commercial mass production of ice cream and the birth of the modern ice cream industry.

The most common method for producing ice cream at home is to use an ice cream maker, in modern times generally an electrical device that churns the ice cream mixture while cooled inside a household freezer, or using a solution of pre-frozen salt and water, which gradually melts while the ice cream freezes. Some more expensive models have an inbuilt freezing element. A newer method of making home-made ice cream is to add liquid nitrogen to the mixture while stirring it using a spoon or spatula.

Ice cream can be mass-produced and thus is widely available in developed parts of the world. Ice cream can be purchased in large cartons (vats and squrounds) from supermarkets and grocery stores, in smaller quantities from ice cream shops and milk bars. In Turkey and Australia, ice cream is sometimes sold to beach-goers from small powerboats equipped with chest freezers. Some ice cream distributors sell ice cream products from traveling refrigerated vans or carts (commonly referred to in the US as "ice cream trucks"), sometimes equipped with speakers playing children's music.

Ice cream may have the following composition:

· Greater than 10% milkfat;

· 9 to 12% milk solids-not-fat: this component, also known as the serum solids, contains the proteins (caseins and whey proteins) and carbohydrates (lactose) found in milk;

· 12 to 16% sweeteners: usually a combination of sucrose and glucose-based corn syrup sweeteners.

Even the low fat products have high caloric content: Ben and Jerry's No Fat Vanilla Fudge contains 150 calories per half cup due to its high sugar content.

History

Precursors of ice cream

Ancient civilizations have served ice for cold foods for thousands of years. Mesopotamia has the earliest icehouses in existence, 4,000 years ago, beside the Euphrates River, where the wealthy stored items to keep them cold. The pharaohs of Egypt had ice shipped to them. In the fifth century BC, ancient Greeks sold snow cones mixed with honey and fruit in the markets of Athens. Persians, having mastered the storage of ice, ate chilled desserts well into summer. Roman Emperor Nero (37-68) had ice brought from the mountains and combined with fruit toppings. These were some early chilled delicacies.

Ancient Persians mastered the technique of storing ice inside giant naturally-cooled refrigerators known as yakhchals. These structures kept ice brought in from the winter, or from nearby mountains, well into the summer.

In 400 BC, Persians invented a special chilled pudding-like dish, made of rose water and vermicelli which was served to royalty during summers. The ice was mixed with saffron, fruits, and various other flavors. The treat, widely made in Iran today, is called "faloodeh", and is made from starch (usually wheat), spun in a sieve-like machine which produces threads or drops of the batter, which are boiled in water. The mix is then frozen, and mixed with rose water and lemons, before serving.

In 62 AD, the Roman emperor Nero sent slaves to the Apennine mountains to collect snow to be flavored with honey and nuts.

Maguelonne Toussaint-Samat asserts in her History of Food, "the Chinese may be credited with inventing a device to make sorbets and ice cream. They poured a mixture of snow and saltpetre over the exteriors of containers filled with syrup, for, in the same way as salt raises the boiling-point of water, it lowers the freezing-point to below zero."

In the sixteenth century, the Mughal emperors used relays of horsemen to bring ice from the Hindu Kush to Delhi where it was used in fruit sorbets.

When Italian duchess Catherine de' Medici married the duc d'Orlйans in 1533, she is said to have brought with her Italian chefs who had recipes for flavored ices or sorbets and introduced them in France. One hundred years later, Charles I of England was supposedly so impressed by the "frozen snow" that he offered his own ice cream maker a lifetime pension in return for keeping the formula secret, so that ice cream could be a royal prerogative. There is, however, no historical evidence to support these legends, which first appeared during the 19th century.

The first recipe for flavored ices in French appears in 1674, in Nicholas Lemery's Recueil .

Recipes for sorbetti saw publication in the 1694 edition of Antonio Latini's Lo Scalco alla Moderna (The Modern Steward).

Recipes for flavored ices begin to appear in Franзois Massialot's Nouvelle Instruction pour les Confitures, les Liqueurs, et les Fruits starting with the 1692 edition. Massialot's recipes result in a coarse, pebbly texture. However, Latini claims that the results of his recipes should have the fine consistency of sugar and snow.

True ice cream

Ice cream recipes first appear in 18th century England and America. A recipe for ice cream was published in Mrs. Mary Eales's Receipts in 1718.

Take Tin Ice-Pots, fill them with any Sort of Cream you like, either plain or sweeten'd, or Fruit in it; shut your Pots very close; to six Pots you must allow eighteen or twenty Pound of Ice, breaking the Ice very small; there will be some great Pieces, which lay at the Bottom and Top: You must have a Pail, and lay some Straw at the Bottom; then lay in your Ice, and put in amongst it a Pound of Bay-Salt; set in your Pots of Cream, and lay Ice and Salt between every Pot, that they may not touch; but the Ice must lie round them on every Side; lay a good deal of Ice on the Top, cover the Pail with Straw, set it in a Cellar where no Sun or Light comes, it will be froze in four Hours, but it may stand longer; than take it out just as you use it; hold it in your Hand and it will slip out. When you wou'd freeze any Sort of Fruit, either Cherries, Rasberries, Currants, or Strawberries, fill your Tin-Pots with the Fruit, but as hollow as you can; put to them Lemmonade, made with Spring-Water and Lemmon-Juice sweeten'd.

Ice cream was introduced to the United States by Quaker colonists who brought their ice cream recipes with them. Confectioners sold ice cream at their shops in New York and other cities during the colonial era.

Around 1832, Augustus Jackson, an African American confectioner, not only created multiple ice cream recipes, but he also invented a superior technique to manufacture ice cream.

In 1843, Nancy Johnson of Philadelphia was issued the first U.S. patent for a small-scale handcranked ice cream freezer. The invention of the ice cream soda gave Americans a new treat, adding to ice cream's popularity. This cold treat was probably invented by Robert Green in 1874, although there is no conclusive evidence to prove his claim.

The ice cream sundae originated in the late 19th century. Several men claimed to have created the first sundae, but there is no conclusive evidence to back up any of their stories. Towns claiming to be the birthplace of the sundae include Buffalo, New York; Two Rivers, Wisconsin; Ithaca, New York; and Evanston, Illinois. Both the ice cream cone and banana split became popular in the early 20th century. Several food vendors claimed to have invented the ice cream cone at the 1904 World's Fair in St. Louis, MO, and reliable evidence proves that the ice cream cone was popularized at the fair. However, Europeans were eating cones long before 1904.

In the UK, ice cream remained an expensive and rare treat, until large quantities of ice began to be imported from Norway and the US in the mid Victorian era. A Swiss-Italian businessman, Carlo Gatti, opened the first ice cream stall outside Charing Cross station in 1851, selling scoops of ice cream in shells for one penny.

The history of ice cream in the 20th century is one of great change and increases in availability and popularity. In the United States in the early 20th century, the ice cream soda was a popular treat at the soda shop.

Ice cream became popular throughout the world in the second half of the 20th century after cheap refrigeration became common. There was an explosion of ice cream stores and of flavors and types. Vendors often competed on the basis of variety. Howard Johnson's restaurants advertised "a world of 28 flavors." Baskin-Robbins made its 31 flavors. The company now boasts that it has developed over 1000 varieties.

One important development in the 20th century was the introduction of soft ice cream. A chemical research team in Britain (of which a young Margaret Thatcher was a member) discovered a method of doubling the amount of air in ice cream, which allowed manufacturers to use less of the actual ingredients, thereby reducing costs. This ice cream was also popular amongst consumers who preferred the lighter texture, and most major ice cream brands now use this manufacturing process.

Ice cream throughout the world

Argentina

The tradition of ice cream making was taken to Argentina by many Italian immigrants. While industrial ice cream exists in Argentina and can be found in supermarkets, restaurants or kiosks, and ice cream pops are sold on some streets and at the beaches, the most traditional Argentinean helado (ice cream) is very similar to Italian gelato, rather than US-style ice cream, and it has become one of the most popular desserts in the country. Among the most famous manufacturers are Freddo, Persicco, Chungo and Munchi's, all of them located in Buenos Aires. However, each city has its own heladerнas (ice cream parlours) which offer different varieties of creamy and water-based ice creams, including both standard and regional flavors. There are hundreds of flavors but Argentina's most traditional and popular one is dulce de leche, which has become a favorite abroad, especially in the US.

There are two kinds of heladerнas in Argentina: the cheaper ones which sell ice cream with artificial ingredients (like Helarte, Pirulo and Sei Tu), and the ones that sell helado artesanal, made with natural. There are no regulations in Argentina regarding the amount of milk an ice cream can have. In fact, all ice cream parlors serve both cream-based and water-based ice cream (helado a la crema and helado al agua respectively). Instead, the distinctions are made according to the quality of the ingredients.

Unlike most other countries, a standard Argentinean cone or cup contains two different flavors of ice cream. In addition to these, most heladerнas offer ice-cream-based desserts like Bombуn Suizo (Swiss Bombom: chocolate-covered chantilly ice cream filled with dulce de leche and sprinkled with nuts), Bombуn Escocйs (Scottish Bombom: same as the Swiss Bombom, only with chocolate ice-cream and white chocolate topping), Cassata (strawberry, vanilla and chocolate ice cream) and Almendrado (almond ice cream sprinkled with almond praline).

Australia and New Zealand

An ice cream van at Batemans Bay, New South Wales, Australia

Per capita, Australians and New Zealanders are among the leading ice cream consumers in the world, eating 18 liters and 20 liters each per year respectively, behind the United States where people eat 23 liters each per year. Brands include Streets, Peters, Sara Lee, New Zealand Natural, Cadbury, and Baskin-Robbins.

Finland

The first ice cream manufacturer in Finland was the Italian Magi family, who opened the Helsingin jддtelцtehdas in.

Finland's first ice cream bar opened at the Lasipalatsi in 1936, and at the same time another manufacturer, Maanviljelijдin Maitokeskus started their production.

Today, the two largest ice cream manufacturers are Ingman and Nestlй (who bought Valiojддtelц). Finland is also the leading consumer of ice cream in Europe, with 13.7 liters per person in 2003.

France

In 1651, Italian Francesco dei Coltelli opened an ice cream cafй in Paris and the product became so popular that during the next 50 years another 250 cafйs opened in Paris. Some "French Style" ice creams are made with butter in place of cream.

Germany

Italian ice cream parlors (Eisdielen) have been popular in Germany since the 1920s, when many Italians immigrated and set up business. As in Italy itself, ice cream is considered a traditional dessert and the ice cream at an Eisdiele is still mostly hand-made.

Greece

Ice cream in its modern form is a relatively new invention. Ice treats have been enjoyed since ancient times. During the 5th century BC, ancient Greeks ate snow mixed with honey and fruit in the markets of Athens. The father of modern medicine, Hippocrates, encouraged his Ancient Greek patients to eat ice "as it livens the lifejuices and increases the well-being."In the 4th century BC, it was well known that a favorite treat of Alexander the Great was snow ice mixed with honey and nectar. In modern times Greek ice cream recipes have some unique flavors such as Pagoto Kaimaki, (Greek: Рбгщфь КбъмЬкй), made from mastic-resin which gives it an almost chewy texture, and salepi, used as a thickening agent to increase resistance to melting; both give the ice cream a unique taste; Olive Oil Ice Cream with figs; Pagoto Kataifi Chocolate, (Greek: Рбгщфь КбфбАцй-кбкЬп), made from the shredded filo dough pastry that resembles angel's hair pasta or vermicelli; and Mavrodaphne Ice Cream, (Greek: МбхспдЬцнз Рбгщфь), made from a Greek dessert wine. Fruity Greek Sweets of the Spoon are usually served as toppings with Greek-inspired ice cream flavors.

India and Pakistan

Kulfi is a traditional dessert that is much denser than traditional ice cream; it is also very popular and widely consumed in both countries. With the presence of major ice cream brands like, AMUL, HAVMOR, KWALITY WALLS, MOTHER DAIRY and VADILAL there is a countrywide availability of various ice cream flavors. There are also ice cream joints like that of Baskin Robbins which have some unique flavors of ice creams and are costlier then packaged ice cream.

Italy

Ice cream is a traditional dessert in Italy. Much is still hand-made by individual gelateria in "produzione propria" ice cream shops. Italian ice cream or gelato is made from whole milk, eggs, sugar, and natural flavorings. Gelato typically contains 7-8% fat, less than ice cream's minimum of 10%.

Some of the most known ice cream machine makers are Italian companies Carpigiani, Crm-Telme, Corema-Telme, Technogel, Cattabriga, Matrix, and Promag.

Japan

Ice cream is also a popular dessert in Japan, with almost two in five adults eating some at least once a week, according to a recent survey.The top four flavors are vanilla, chocolate, matcha (powdered green tea), and strawberry. Other notable popular flavors are milk, caramel, and azuki (Red Bean). Azuki is particularly favored by people in their 50s and older.While matcha is a truly Japanese flavor favored by Japanese and well-known among non-Japanese outside of Japan, plum and ginger, tastes often presented as Japanese flavors outside of Japan. In Japan, a soft serve ice cream is called softcream which is also very popular. As a seasonal treat during the cherry blossom season, ice cream is available that is actually flavored with cherry blossoms.

Philippines

Sorbetes is a Filipino version for common ice cream usually peddled from carts that roam streets in the Philippines. This should not be confused with the known sorbet. It is also commonly called 'dirty ice cream.It is usually served with small wafer or sugar cones and recently, bread buns.

Spain

Ice cream, in the style of Italian gelato, can be found in many cafes or specialty ice cream stores throughout. Usually the flavors reflect local tastes like nata, crema catalana, or tiramisu.

United Kingdom

In the United Kingdom, per capita consumption of ice cream is 6 liters per year. A product may be sold as "ice cream" if it contains 5 per cent fat and not less than 2.5 per cent milk protein, but may contain non-milk vegetable fats and oils, usually hydrogenated palm kernel oil, which is more permissive than many other countries. Only true ice cream made only with milk fats (though not necessarily cream) can be described as dairy ice cream.

United States

In the United States, ice cream made with just cream, sugar, and a flavoring (usually fruit) is sometimes referred to as "Philadelphia style"ice cream. Ice creams made with eggs, usually in the form of custards, are "French" ice creams.

American federal labeling standards require ice cream to contain a minimum of 10% milk fat (about 7 grams (g) of fat per 1/2 cup [120 mL] serving) and 20% total milk solids by weight.

Ice cream is an extremely popular dessert in the United States. Americans consume about 15 quarts (more than 13 liters) of ice cream per person per year -- the most in the world. Although chocolate, vanilla, and strawberry are the traditional favorite flavors of ice cream, and once enjoyed roughly equal popularity, vanilla has grown to be far and away the most popular. According to the International Ice Cream Association (1994), supermarket sales of ice cream break down as follows: vanilla, 28%; fruit flavors, 15%; nut flavors, 13.5%; candy mix-in flavors, 12.5%; chocolate, 8%; cake and cookie flavors, 7.5%; Neapolitan, 7%; and coffee/mocha, 3%. Other flavors combine for 5.5%.

Other frozen desserts

Raspberry sorbet

· Ais kacang - a dessert in Malaysia and Singapore made from shaved ice, syrup, and boiled red bean and topped with chocolate sauce and evaporated milk. Sometimes, other small ingredients like raspberries and durians are added in too.

· Dondurma: - Turkish ice cream, made of salep and mastic resin

· Frozen custard - at least 10% milk fat and at least 1.4% egg yolk and much less air beaten into it, similar to Gelato, fairly rare. Known in Italy as Semifreddo.

· Frozen yogurt - a low fat.

· Gelato - an Italian frozen dessert having a lower milk fat content than ice cream and stabilized with ingredients such as eggs.

· Ice milk - less than 10% milk fat and lower sweetening content, once marketed as "ice milk" but now sold as low-fat ice cream in the United States.

· Ice pop (or lolly) - frozen fruit puree, fruit juice, or flavored sugar water on a stick or in a flexible plastic sleeve.

Kefir

Kefir (alternately kefоrs, keefir, kephir, kewra, talai, mudu kekiya, milkkefir, bъlgaros) is a fermented milk drink that originated in the Caucasus region. It is prepared by inoculating cow, goat, or sheep's milk with kefir grains. Traditional kefir was made in skin bags that were hung near a doorway; the bag would be knocked by anyone passing through the doorway to help keep the milk and kefir grains well mixed.