Cheese is a solid food made from the curdled milk of cows, goats, sheep, water buffalo or 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.
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 traditionally obtained from the stomach lining of young cattle, but now also laboratory produced. It acts by breaking down the major milk protein casein into small fragments, leading to coagulation. Substitute "vegetable rennets" have been extracted from various species of the Cynara thistle family.
Cheeses can be eaten either raw or cooked, alone or with other ingredients. As they are heated, most cheeses melt and brown. Some cheeses, like raclette, melt smoothly; many others can be coaxed into doing so in the presence of acids or starch. Fondue, with wine providing the acidity, is a good example of a smoothly-melted cheese dish. Other cheeses turn elastic and stringy when they melt, a quality that can be enjoyed in dishes like pizza and Welsh rabbit. Some cheeses melt unevenly, their fats separating as they heat, while a few acid-curdled cheeses, including halloumi, paneer and ricotta, do not melt at all and can become firmer when cooked.
Cheese has served as a hedge against famine and 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 money is needed.
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.
By Roman times, cheese was an everyday food and cheesemaking a mature art, not very different from what it is today. Columella's De Re Rustica (circa 65 CE) details a cheesemaking process involving rennet coagulation, pressing of the curd, salting, and aging. Pliny's Natural History (77 CE) devotes a chapter (XI, 97) to describing the diversity of cheeses enjoyed by Romans of the early Empire. He stated that the best cheeses came from the villages near Nîmes, but did not keep long and had to be eaten fresh. Cheeses of the Alps and Apennines were as remarkable for their variety then as now. A Ligurian cheese was noted for being made mostly from sheep's milk, and some cheeses produced nearby were stated to weigh as much as a thousand pounds each. Goats' milk cheese was a recent taste in Rome, improved over the "medicinal taste" of Gaul's similar cheeses by smoking. Of cheeses from overseas, Pliny preferred those of Bithynia in Asia Minor.
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.)Cecil Adams (1999). Straight Dope: How did the moon=green cheese myth start?. Retrieved October 15, 2005. 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.
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. p 54. "In the United States, the market for process cheese * is now larger than the market for 'natural' cheese, which itself is almost exclusively factory-made." 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 was produced worldwide in 2004. This is more than the yearly production of coffee beans, tea leaves, cocoa beans and tobacco combined. Germany is the largest importer of cheese from France, the major exporter.
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 halalToronto Public Health. Frequently Asked Questions about Halal Foods. Retrieved October 15, 2005. 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."McGee p 58, "Why Some People Can't Stand Cheese."
No one categorization scheme can capture all the diversity of the world's cheeses. These are some commonly used classifications.
Whey cheeses are fresh cheeses made from the whey discarded while producing other cheeses. Ricotta, Romanian Urda and Norwegian Geitost are examples.
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.
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.
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).
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.
Processed cheese is made from traditional cheese and emulsifiers, 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 shares milk's nutritional disadvantages as well. The Center for Science in the Public Interest condemns 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.Center for Science in the Public Interest (2001). Don't Say Cheese. Retrieved October 15, 2005. 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.McGee, p 67. McGee supports both this contention and that more food poisonings in Europe are caused by pasteurized cheeses than raw-milk. 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".FDA Warns About Soft Cheese Health Risk. Retrieved October 15, 2005. 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.Chris Mercer (2005). Australia lifts Roquefort cheese safety ban. Retrieved October 22, 2005. 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.Janet Fletcher. The Myths About Raw-Milk Cheese. Retrieved October 15, 2005. 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.Listeria and pregnancy, from the American Pregnancy Association. Retrieved 28 February 2006.
Some studies claim to show that cheeses including Cheddar, Mozzarella, Swiss and American can help to prevent tooth decay.National Dairy Council. Specific Health Benefits of Cheese. Retrieved October 15, 2005. Several mechanisms for this protection have been proposed:
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.Lactose Intolerance FAQs from the American Dairy Association. Retrieved October 15, 2005. 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.
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.
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:
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.
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.
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.Michael Quinion (2000). World Wide Words: Big Cheese. Retrieved October 15, 2005.
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.Straight Dope Staff Report (2005). Why do photographers ask you to say "cheese"?. Retrieved October 15, 2005. 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.
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