History
Origins
Ancient Greece / Rome
Post-Classical Europe
Modern Era
World Production and Consumption
Cultural Attitudes
Types of Cheese

Cheese is a solid food made from the milk of cows, goats, sheep, and other mammals. The milk is curdled using some combination of rennet (or rennet substitutes) and acidification. Bacteria acidify the milk and play a role in defining the texture and flavor of most cheeses. Some cheeses also feature molds, either on the outer rind or throughout.

There are hundreds of types of cheese produced all over the world. Different styles and flavors of cheese are the result of using different species of bacteria and molds, different levels of milk fat, variations in length of aging, differing processing treatments (cheddaring, pulling, brining, mold wash) and different breeds of cows, sheep, or

other mammals. Other factors include animal diet and the addition of flavoring agents such as herbs, spices, or wood smoke. Whether the milk is pasteurized may also affect the flavor. The yellow to red coloring of many cheeses is a result of adding annatto. Cheeses are eaten both on their own and cooked into various dishes; most cheeses melt when cooked.

For a few cheeses, the milk is curdled by adding acids such as vinegar or lemon juice. Most cheeses, however, are acidified to a lesser degree by bacteria, which turn milk sugars into lactic acid, followed by the addition of rennet to complete the curdling. Rennet is an enzyme mixture traditionally obtained from the stomach lining of young cattle, but now also laboratory produced. Vegetarian alternatives to rennet are also available; most are produced by fermentation of the fungus Mucor miehei, but substitute "vegetable rennets" have also been extracted from various species of the Cynara thistle family.

The word cheese is derived from the Middle English chese, from the Old English cīese or cēse, itself derived from the Latin caseus.

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History
Cheese is an ancient food whose origins may predate recorded history. Probably discovered in Central Asia or the Middle East, cheesemaking spread to Europe and had become a sophisticated enterprise by Roman times. As Rome's influence receded, distinct local cheesemaking techniques emerged. This diversity reached its peak in the early industrial age and has declined somewhat since then due to mechanization and economic factors.

Cheese has served as a hedge against famine and is a good travel food. It is valuable for its portability, long life, and high content of fat, protein, calcium, and phosphorus. Cheese is lighter-weight, more compact, and has a longer shelf life than the milk from which it is made. Cheesemakers can place themselves near the center of a dairy region and benefit from fresher milk, lower milk prices, and lower shipping costs. Cheese's substantial storage life lets a cheesemaker sell when prices are high or when money is needed.

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Origins
The exact origins of cheesemaking are debated or unknown, and estimates range from around 8000 BCE (when sheep were domesticated) to around 3000 BCE. Credit for the discovery most likely goes to nomadic Turkic tribes in Central Asia, around the same time that they developed yogurt, or to people in the Middle East. A common tale about the discovery of cheese tells of an Arab nomad carrying milk across the desert in a container made from an animal's stomach, only to discover the milk had been separated into curd and whey by the rennet from the stomach.

Folktales aside, cheese likely began as a way of preserving soured and curdled milk through pressing and salting, with rennet introduced later— perhaps when someone noticed that cheese made in an animal stomach produced more solid and better-textured curds. The earliest archaeological evidence of cheesemaking has been found in Egyptian tomb murals, dating to about 2300 BCE. The earliest cheeses would likely have been quite sour and salty, similar in texture to rustic cottage cheese or feta.

From the Middle East, basic cheesemaking found its way into Europe, where cooler climates meant less aggressive salting was needed for preservation. With moderate salt and acidity, the cheese became a suitable environment for a variety of beneficial microbes and molds, which are what give aged cheeses their pronounced and interesting flavors.

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Ancient Greece/Rome
Ancient Greek mythology credited Aristaeus with the discovery of cheese. Homer's Odyssey (8th century BCE) describes the Cyclops making and storing sheep's and goats' milk cheese. From Samuel Butler's translation:

We soon reached his cave, but he was out shepherding, so we went inside and took stock of all that we could see. His cheese-racks were loaded with cheeses, and he had more lambs and kids than his pens could hold...

When he had so done he sat down and milked his ewes and goats, all in due course, and then let each of them have her own young. He curdled half the milk and set it aside in wicker strainers... By Roman times, cheese was an everyday food and cheesemaking a

cheeses by smoking. Of cheeses from overseas, Pliny preferred those of Bithynia in Asia Minor.

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Post-classical Europe
Rome spread a uniform set of cheesemaking techniques throughout much of Europe, and introduced cheesemaking to areas without a previous history of it. As Rome declined and long-distance trade collapsed, cheese in Europe diversified further, with various locales developing their own distinctive cheesemaking traditions and products. France and Italy are the nations with the most diversity in locally made cheeses— today with approximately 400 each. (A French proverb holds there is a different French cheese for every day of the year, and Charles de Gaulle once asked "how can you govern a country in which there are 246 kinds of cheese?") Still, the advancement of the cheese art in Europe was slow during the centuries after Rome's fall. Many of the cheeses we know best today were first recorded in the late Middle Ages or after— cheeses like cheddar around 1500 CE, Parmesan in 1597, Gouda in 1697, and Camembert in 1791.

In 1546, John Heywood wrote in Proverbes that "the moon is made of a greene cheese." (Greene refers here not to the color, as many now think, but to being new or unaged.) Variations on this sentiment were long repeated. Although some people assumed that this was a serious belief in the era before space exploration, it is more likely that Heywood was indulging in nonsense.

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Modern era
Until its modern spread along with European culture, cheese was nearly unheard of in oriental cultures, uninvented in the pre-columbian Americas, and of only limited use in sub-mediterranean Africa, mainly being widespread and popular only in Europe and areas influenced strongly by its cultures. But with the spread, first of European imperialism, and later of Euro-American culture and food, cheese has gradually become known and increasingly popular worldwide, though still rarely considered a part of local ethnic cuisine.

St Pat Goat's Milk CheeseThe first factory for the industrial production of cheese opened in Switzerland in 1815, but it was in the United States where large-scale production first found real success. Credit usually goes to Jesse Williams, a dairy farmer from Rome, New York, who in 1851 started making cheese in an assembly-line fashion using the milk from neighboring farms. Within decades hundreds of such dairy associations existed.

The 1860s saw the beginnings of mass-produced rennet, and by the turn of the century scientists were producing pure microbial cultures. Before then, bacteria in cheesemaking had come from the environment or from recycling an earlier batch's whey; the pure cultures meant a more standardized cheese could be produced.

Factory-made cheese overtook traditional cheesemaking in the World War II era, and factories have been the source of most cheese in America and Europe ever since. Today, Americans buy more processed cheese than "real", factory-made or not.

States,accounting for 30 percent of world production, followed by Germany and France.

The biggest exporter of cheese, by monetary value, is France; the second, Germany (although it is first by quantity). Among the top ten exporters, only Ireland, New Zealand, the Netherlands and Australia have a cheese production that is mainly export oriented: respectively 95 percent, 90 percent, 72 percent, and 65 percent of their cheese production is exported. Only 30 percent of French production, the world's largest exporter, is exported. The United States, the biggest world producer of cheese, is a marginal exporter, as most of its production is for the domestic market.

Germany is the largest importer of cheese. UK and Italy are the second- and third-largest importers.

Greece is the world's largest (per capita) consumer of cheese, with 27.3 kg eaten by every Greek. (Feta accounts for three-quarters of this consumption.) France is the second biggest consumer of cheese, with 24 kg by inhabitant. Emmental (used mainly as a cooking ingredient) and Camembert are the most common cheeses in France. Italy is the third biggest consumer by person with 22.9 kg. In the U.S., the consumption of cheese is quickly increasing and has nearly tripled between 1970 and 2003. The consumption per person has reached, in 2003, 14.1 kg (31 pounds). Mozzarella is America's favorite cheese and accounts for nearly a third of its consumption.

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Cultural attitudes
Cheese is rarely found in East Asian dishes, as dairy products in general are rare. However, East Asian sentiment against cheese is not universal. Cheese made from yaks' (chhurpi) or mares' milk is common on the Asian steppes; the national dish of Bhutan, ema datsi, is made from homemade cheese and hot peppers; and cheese is used in India, where paneer curries are popular. Even in China, cheese consumption is increasing, with annual sales more than doubling from 1996 to 2003 (to a still small 30 million U.S. dollars a year). Certain kinds of Chinese preserved bean curd are sometimes misleadingly referred to in English as "Chinese cheese", due to their texture and strong flavor.

Strict followers of the dietary laws of Judaism and Islam must avoid cheeses made with rennet from animals not slaughtered in a manner adhering to kosher or halal laws. Both faiths allow cheese made with vegetable-based rennet or with rennet made from animals that were processed in a kosher or halal manner. Many less-orthodox Jews also believe that rennet undergoes enough processing to change its nature entirely, and do not consider it to ever violate kosher law. (See Cheese and kashrut.) As cheese is a dairy food under kosher rules it cannot be eaten in the same meal with any meat.

Many vegetarians avoid any cheese made from animal-based rennet. Most widely available vegetarian cheeses are made using rennet produced by fermentation of the fungus Mucor miehei. Vegans and other dairy-avoiding vegetarians do not eat real cheese at all, but some vegetable-based substitute cheeses (usually soy-based) are available.

Even in cultures with long cheese traditions, it is not unusual to find people who perceive cheese — especially pungent-smelling or mold-bearing varieties such as Limburger or Roquefort — as unappetizing, unpalatable, or disgusting. Food-science writer Harold McGee proposes that cheese is such an acquired taste because it is produced through a process of controlled spoilage and many of the odor and flavor molecules in an aged cheese are the same found in rotten foods. McGee notes "An aversion to the odor of decay has the obvious biological value of steering us away from possible food poisoning, so it's no wonder that an animal food that gives off whiffs of shoes and soil and the stable takes some getting used to."

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Types of cheese
No one categorization scheme can capture all the diversity of the world's cheeses.

Some common systems used are:

• Length of aging.
• Texture (hard or soft); this is correlated to the moisture content: the more moist a cheese, the softer. This classification is common in the US, but is inaccurate: many types of cheese are made in softer or firmer variations.
• Methods of making: pressed or unpressed curd, heated or unheated curd, mold growth, etc.
• Fat content.
• Kind of milk (cow's milk, goat's milk cheese, etc.)

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Aging period

Fresh
For these simplest cheeses, milk is curdled and drained, with little other processing. Examples include cottage cheese, Romanian Caş, Neufchâtel (the model for American-style cream cheese), and fresh goat's milk chèvre. Such cheeses are soft and spreadable, with a mild taste. Fresh cheeses without additional preservatives can spoil in a matter of days.

Whey cheeses are fresh cheeses made from the whey discarded while producing other cheeses. Provencal Brousse, Corsican Brocciu, Italian Ricotta, Romanian Urda and Norwegian Geitost are examples. Brocciu is mostly eaten fresh, and is as such a major ingredient in Corsican cuisine, but it can be aged too.

Traditional Mozzarella also falls into the fresh cheese category. Fresh curds are stretched and kneaded in hot water to form a ball of Mozzarella, which in southern Italy is usually eaten within a few hours of being made. Other firm fresh cheeses include paneer and queso fresco.

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Texture
A Gouda cheese marketCategorizing cheeses by firmness is a common but inexact practice. The lines between "soft", "semi-soft", "semi-hard", and "hard" are arbitrary, and many types of cheese are made in softer or firmer variations. Harder cheeses have a lower moisture content than softer cheeses. They are generally packed into molds under more pressure and aged for a longer time.

The familiar cheddar is one of a family of semi-hard or hard cheeses (including Cheshire and Gloucester) whose curd is cut, gently heated, piled, and stirred before being pressed into forms. Colby and Monterey Jack are similar but milder cheeses; their curd is rinsed before it is pressed, washing away some acidity and calcium. A similar curd-washing takes place when making the Dutch cheeses Edam and Gouda.

Swiss-style cheeses like Emmental and Gruyère are generally quite firm. The same bacteria that give Emmental its holes contribute to their aromatic and sharp flavors. The hardest cheeses — "grating cheeses" such as Parmesan, Pecorino, and Romano — are quite firmly packed into large forms and aged for months or years.

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Methods

Use of mold
Soft-ripened cheeses such as Brie and Camembert are made by allowing white Penicillium candida or P. camemberti mold to grow on the outside of a soft cheese for a few days or weeks. The mold forms a white crust and contributes to the smooth, runny, or gooey textures and more intense flavors of these aged cheeses. Goats' milk cheeses are often treated in a similar manner, sometimes with white molds (Chèvre-Boîte) and sometimes with blue.

Blue-mold cheeses like Roquefort, Gorgonzola, and Stilton are produced by inoculating loosely pressed curds with Penicillium roqueforti or Penicillium glaucum molds. The mold grows within the cheese as it ages. These cheeses have distinct blue veins and, often, assertive flavors. Their texture can be soft or firm.

Washing
Washed-rind cheeses are periodically bathed in a saltwater brine as they age, making their surfaces amenable to a class of bacteria (the reddish-orange "smear bacteria") which impart pungent odors and distinctive flavors. Washed-rind cheeses can be soft (Limburger), semi-hard ( Munster), or hard (Appenzeller).

Processed cheese is made from traditional cheese and emulsifying salts, often with the addition of milk, more salt, preservatives, and food coloring. It is inexpensive, consistent, and melts smoothly. This is the most-consumed category of cheese in the United States. The most familiar processed cheese may be pre-sliced mild yellow American Cheese or Velveeta. Many other varieties exist, including Easy Cheese, a Kraft Foods brand sold in a spray can.

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Health and nutrition
In general, cheese supplies a great deal of calcium, protein, and phosphorus. A 30 gram (one ounce) serving of cheddar cheese contains about seven grams of protein and 200 milligrams of calcium. Nutritionally, cheese is essentially concentrated milk: it takes about 200 grams (seven ounces) of milk to provide that much protein, and 150 grams to equal the calcium.

Cheese shares milk's nutritional disadvantages as well. The Center for Science in the Public Interest describes cheese as America's number one source of saturated fat, adding that the average American ate 30 pounds (13.6 kg) of cheese in the year 2000, up from 11 pounds (5 kg) in 1970. Their recommendation is to limit full-fat cheese consumption to two ounces (60 grams) a week. Whether cheese's highly saturated fat actually leads to an increased risk of heart disease is called into question when considering France and Greece, which lead the world in cheese eating (more than 14 ounces (400 grams) a week per person, or over 45 pounds (20 kg) a year) yet have relatively low rates of heart disease. This seeming discrepancy is called the French Paradox; the higher rates of consumption of red wine in these countries is often invoked as at least a partial explanation.

A number of food safety agencies around the world have warned of the risks of raw-milk cheeses. The U.S. Food and Drug Administration states that soft raw-milk cheeses can cause "serious infectious diseases including listeriosis, brucellosis, salmonellosis and tuberculosis". It is U.S. law since 1944 that all raw-milk cheeses (including imports since 1951) must be aged at least 60 days. Australia has a wide ban on raw-milk cheeses as well, though in recent years exceptions have been made for Swiss Gruyère, Emmental and Sbrinz, and for French Roquefort. Some say these worries are overblown, pointing out that pasteurization of the milk used to make cheese does not ensure its safety in any case. This is supported by statistics showing that in Europe (where young raw-milk cheeses are still legal in some countries), most cheese-related food poisoning incidents were traced to pasteurized cheeses. Pregnant women may face an additional risk from cheese; the U.S. Centers for Disease Control has warned pregnant women against eating soft-ripened cheeses and blue-veined cheeses, due to the listeria risk to the unborn baby.

Some studies claim to show that cheeses including Cheddar, Mozzarella, Swiss and American can help to prevent tooth decay. Several mechanisms for this protection have been proposed:

• The calcium, protein, and phosphorus in cheese may act to protect tooth enamel.
• Cheese increases saliva flow, washing away acids and sugars.
• Cheese may have an antibacterial effect in the mouth.

Cheese is often avoided by those who are lactose intolerant, but ripened cheeses like Cheddar contain only about 5% of the lactose found in whole milk, and aged cheeses contain almost none. Some people suffer reactions to amines found in cheese, particularly histamine and tyramine. Some aged cheeses contain significant concentrations of these amines, which can trigger symptoms mimicking an allergic reaction: headaches, rashes, and blood pressure elevations.

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Making cheese

Curdling
The only strictly required step in making any sort of cheese is separating the milk into solid curds and liquid whey. Usually this is done by acidifying the milk and adding rennet. The acidification is accomplished directly by the addition of an acid like vinegar in a few cases (paneer, queso fresco), but usually starter bacteria are employed instead. These starter bacteria convert milk sugars into lactic acid. The same bacteria (and the enzymes they produce) also play a large role in the eventual flavor of aged cheeses. Most cheeses are made with starter bacteria from the Lactococci, Lactobacilli, or Streptococci families. Swiss starter cultures also include Propionibacter shermani, which produces carbon dioxide gas bubbles during aging, giving Swiss cheese or Emmental its holes.

Some fresh cheeses are curdled only by acidity, but most cheeses also use rennet. Rennet sets the cheese into a strong and rubbery gel compared to the fragile curds produced by acidic coagulation alone. It also allows curdling at a lower acidity—important because flavor-making bacteria are inhibited in high-acidity environments. In general, softer, smaller, fresher cheeses are curdled with a greater proportion of acid to rennet than harder, larger, longer-aged varieties.

Curd processing
At this point, the cheese has set into a very moist gel. Some soft cheeses are now essentially complete: they are drained, salted, and packaged. For most of the rest, the curd is cut into small cubes. This allows water to drain from the individual pieces of curd.

Some hard cheeses are then heated to temperatures in the range of 35°C–55°C (100°F–130°F). This forces more whey from the cut curd. It also changes the taste of the finished cheese, affecting both the bacterial culture and the milk chemistry. Cheeses that are heated to the higher temperatures are usually made with thermophilic starter bacteria which survive this step—either lactobacilli or streptococci.

Salt has a number of roles in cheese besides adding a salty flavor. It preserves cheese from spoiling, draws moisture from the curd, and firms up a cheese’s texture in an interaction with its proteins. Some cheeses are salted from the outside with dry salt or brine washes. Most cheeses have the salt mixed directly into the curds.

A number of other techniques can be employed to influence the cheese's final texture and flavor. Some examples:

• Stretching: (Mozzarella, Provolone) The curd is stretched and kneaded in hot water, developing a stringy, fibrous body.
• Cheddaring: (Cheddar, other English cheeses) The cut curd is repeatedly piled up, pushing more moisture away. The curd is also mixed (or milled) for a long period of time, taking the sharp edges off the cut curd pieces and influencing the final product's texture.
• Washing: ( Edam, Gouda, Colby) The curd is washed in warm water, lowering its acidity and making for a milder-tasting cheese.

Most cheeses achieve their final shape when the curds are pressed into a mold or form. The harder the cheese, the more pressure is applied. The pressure drives out moisture — the molds are designed to allow water to escape — and unifies the curds into a single solid body.

Aging
A newborn cheese is usually salty yet bland in flavor and, for harder varieties, rubbery in texture. These qualities are sometimes enjoyed—cheese curds are eaten on their own—but usually cheeses are left to rest under carefully controlled conditions. This aging period (also called ripening, or, from the French, affinage) can last from a few days to several years. As a cheese ages, microbes and enzymes transform its texture and intensify its flavor. This transformation is largely a result of the breakdown of casein proteins and milkfat into a complex mix of amino acids, amines, and fatty acids.

Some cheeses have additional bacteria or molds intentionally introduced to them before or during aging. In traditional cheesemaking, these microbes might be already present in the air of the aging room; they are simply allowed to settle and grow on the stored cheeses. More often today, prepared cultures are used, giving more consistent results and putting fewer constraints on the environment where the cheese ages.

For the blue cheeses (Roquefort, Stilton, Gorgonzola), Penicillium mold is introduced to the curd before molding. During aging, the blue molds (P. roqueforti or P. glaucum ) grow in the small fissures in the cheese, imparting a sharp flavor and aroma. The same molds are also grown on the surface of some aged goat cheeses. The soft cheeses Brie and Camembert, among others, get a surface growth of other Penicillium species, white-colored P. candidum or P. camemberti. The surface mold contributes to the interior texture and flavor of these small cheeses.

on cheeses that are simply ripened in humid conditions, like Camembert. Large populations of these "smear bacteria" show up as a sticky orange-red layer on some brine-washed cheeses.

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Eating and cooking
At refrigerator temperatures, the fat in a piece of cheese is as hard as unsoftened butter, and its protein structure is stiff as well. Flavor and odor compounds are less easily liberated when cold. For improvements in flavor and texture, it is widely advised that cheeses be allowed to warm up to room temperature before eating. Warm up a piece of cheese up a little more, to 26–32°C (80–90°F), and the fats start to "sweat out" as they go beyond soft to fully liquid.

At higher temperatures, most cheeses melt. Rennet-curdled cheeses have a gel-like protein matrix that is broken down by heat. When enough protein bonds are broken, the cheese itself turns from a solid to a viscous liquid. Soft, high-moisture cheeses will melt at around 55°C (130°F), while hard, low-moisture cheeses such as Parmesan remain solid until they reach about 82°C (180°F). Acid-set cheeses, including halloumi, paneer, some whey cheeses and many varieties of fresh goat cheese, have a protein structure that remains intact at high temperatures. When cooked, these cheeses just get firmer as water evaporates.

Some cheeses, like raclette, melt smoothly; many tend to become stringy or suffer from a separation of their fats. Many of these can be coaxed into melting smoothly in the presence of acids or starch. Fondue, with wine providing the acidity, is a good example of a smoothly-melted cheese dish. Elastic stringiness is a quality that is sometimes enjoyed, in dishes including pizza and Welsh rabbit. Even a melted cheese eventually turns solid again, after enough moisture is cooked off. As its temperature continues to rise, cheese will brown and eventually burn.

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Cheese in language
Throughout the history of the English language, the word cheese has been chese (in Middle English) and cīese or cēse (in Old English). Similar words are shared by other West Germanic languages — Frisian tsiis, Dutch kaas, German Käse, Old High German chāsi — all of which probably come from the reconstructed West-Germanic root *kasjus, which in turn is an early borrowing from Latin. The Latin word caseus — from which are derived the Spanish queso, Portuguese queijo,Malay/Indonesian Language keju, Romanian caş and Italian cacio — and the Celtic root which gives the Irish cáis and the Welsh caws are also related. This whole group of words is probably derived from the proto-Indo-European root *kwat-, which means "to ferment, become sour".

When the Romans began to make hard cheeses for their legionaries' supplies, a new word started to be used: formaticum, from caseus formatus, or "molded cheese". It is from this word that we get the French fromage, Italian formaggio, Catalan formatge, Breton fourmaj and Provençal furmo. Cheese itself is occasionally employed in a sense that means "molded" or "formed". Head cheese uses the word in this sense.

In modern English slang, something "cheesy" is kitsch, cheap, inauthentic, or of poor quality. One can also be "cheesed off"— unhappy or annoyed. Such negative connotations might derive from a ripe cheese's sometimes-unpleasant odor. Almost certainly the odor explains the use of "cutting the cheese" as a euphemism for flatulence, and the term "cheesy feet" to mean feet which smell. A more upbeat slang use is seen in "the big cheese", an expression referring to the most important person in a group, the "big shot" or "head honcho". This use of the word probably derived not from the word cheese, but from the Persian or Hindi word chiz, meaning a thing.

A more whimsical bit of American and Canadian slang refers to school buses as "cheese wagons", a reference to school bus yellow. People getting their photo taken are often encouraged to "say cheese!", as the word "cheese" contains the phoneme /i/, a long vowel which requires the lips to be stretched in the appearance of a smile. People from Wisconsin and the Netherlands, both centers of cheese production, have been called cheeseheads. This nickname has been embraced by Wisconsin sports fans — especially fans of the Green Bay Packers or Wisconsin Badgers — who are now seen in the stands sporting plastic or foam hats in the shape of giant cheese wedges.

See also LIST OF CHEESES

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