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Cheese is a food made from the curdled milk of cows, goats, sheep, 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.
Many Cheese Varieties
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 or not 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.
Cooking With Cheese
Cheeses are eaten 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.
Types of cheese
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. 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.
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 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.
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).
Other Cheese Categories
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.
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 Information Courtesy of Wikipedia