Cheese

Cheese is a solid food made from the milk of cows, goats, sheep, and other mammals. Cheese is made by curdling milk using a 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 milk from various mammals or with different butterfat contents, employing particular species of bacteria and molds, and varying the length of aging and other processing treatments. 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 also eaten both on their own and cooked as part of various dishes; most cheeses melt when heated.

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 available; most are produced by fermentation of the fungus Mucor miehei, but others have 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.

History

See How was cheese invented?

World production and consumption

Worldwide, cheese is a major agricultural product. According to the Food and Agricultural Organization of the United Nations, over 18 million metric tons of cheese were produced worldwide in 2004. This is more than the yearly production of coffee, tea, cocoa beans and tobacco combined. The largest producer of cheese is the United States, accounting for 30 percent of world production, followed by Germany and France.

Top Cheese Producers - 2004 (1,000 Metric Tons)
United States	4,327
Germany	1,929
France	1,827
Italy	1,102
Netherlands	672
Poland	535
Brazil	470
Egypt	450
Australia	373
Argentina	370

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.

Top Cheese Exporters (Whole Cow Milk only) - 2004 (value in '000 US $)
France	2,658,441
Germany	2,416,973
Netherlands	2,099,353
Italy	1,253,580
Denmark	1,122,761
Australia	643,575
New Zealand	631,963
Belgium	567,590
Ireland	445,240
United Kingdom	374,156

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

Top Cheese Consumers - 2003 (kilograms per person)
Greece	27.3
France	24
Italy	22.9
Switzerland	20.6
Germany	20.2
Netherlands	19.9
Austria	19.5
Sweden	17.9

Greece is the world's largest (per capita) consumer of cheese, with 27.3 kg eaten by the average 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). Fior di latte (commonly known as mozzarella) is America's favorite cheese and accounts for nearly a third of its consumption.

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."

Types of cheese

Main article: List of cheeses

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.)

Fresh Cheeses

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. Provençal Brousse, Corsican Brocciu, Italian Ricotta, Romanian Urdă 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.

Texture

Categorizing 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.

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.

Cheese is good.:)

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.

It should also perhaps be noted that under certain scientifically controlled dietery studies, people whose diets which particularly consisted of the high intake of dairy foods had shown that obesity had prevailed at a higher rate than of those persons whose diets consisted of only vegetable based fats.

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

File:Production of cheese 1.jpg

During industrial production of Emmental cheese, the as-yet-undrained curd is broken up by rotating mixers.

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.

File:Vacherin du haut Doubs.jpg

Vacherin du Haut-Doubs cheese, a French cheese with a white Penicillium mold rind.

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.

Some cheeses are periodically washed in a saltwater brine during their ripening. Not only does the brine carry flavors into the cheese (it might be seasoned with spices or wine), but the salty environment may nurture the growth of the Brevibacterium linens bacteria, which can impart a very pronounced odor (Limburger) and interesting flavor. The same bacteria can also have some impact 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.

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. If the cheese is further warmed, to 26–32°C (80–90°F), the fats will begin to 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.

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 (most likely from the corruption of the Portuguese word queijo), 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. Subjects of photographs 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.

References

• Jenkins, Steven (1996). Cheese Primer. Workman Publishing Company. ISBN 0-89480-762-5. 
• McGee, Harold (2004). On Food and Cooking (Revised Edition). Scribner. ISBN 0-684-80001-2.  pp 51-63, "Cheese"
• Mellgren, James (2003). "2003 Specialty Cheese Manual, Part II: Knowing the Family of Cheese". http://www.gourmetretailer.com/gourmetretailer/magazine/article_display.jsp?vnu_content_id=1911696. Retrieved 2005-10-12. 

External links

• Cook's Info page on Cheese
• ILoveCheese.com
• University of Guelph Food Science Cheese Site
• Cheese Making Illustrated — The science behind homemade cheese.
• The Complete Book of Cheese at Project Gutenberg
• Cheese.com — includes an extensive database of different types of cheese.