Cheese is a solid food made from the curdled milk of various mammals—most commonly cows but sometimes goats, sheep, or buffalo. Rennet is often used to induce coagulation in the milk, although some cheeses are curdled with acids such as vinegar or lemon juice, or with extracts of various species of Cynara (sometimes called vegetable rennet). Rennet is an enzyme traditionally obtained from the stomach lining of bovine calves, although sometimes a microbiological (laboratory-produced) substitute is used. Bacteria are added to cheese to reduce the pH, alter the texture, and develop flavor, and some cheeses also have molds, either on the outer skin or throughout.
There are hundreds of types of cheese. Different styles and flavors of cheese are the results 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 smoking. Pasteurization of the milk may also affect flavor.
The word cheese comes from the Latin caseus and, later, West Germanic kasjus. Note that cheese in Modern German is Käse.
