Cheese is a foodstuff made from the curdled milk of various
animals, most frequently cows, but often goats, sheep, and water
buffalo. Rennet is often used to induce milk to curdle, although
some cheeses are curdled with acids like vinegar or lemon juice, or
with extracts of various species of Cynara (sometimes called
vegetable rennet). Rennet is an enzyme obtained traditionally from
the stomach lining of bovine calves, but more frequently nowadays,
a microbiological (laboratory produced) substitute is used.
Bacteria are added to cheese to reduce the pH, alter texture, and
develop flavor, and some cheeses also have molds, either on the
outer skin or throughout. The natural color of cheeses range from
off-white to yellow. In some parts of the world, such as Wisconsin
USA, the milk fat is low in beta-carotene, making the cheese a
paler yellow than normal. In this case it is common to add annatto
plant dye as a coloring agent.
Some cheeses are made with the addition of herbs and spices. In
some locations as a response to the loss of diversity in
mass-produced cheeses, a cottage industry has grown up around home
cheesemaking.
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 and differing processing
treatments (cheddaring, pulling, brining, mold wash). Other factors
include milk animal diet and the addition of herbs and spices to
some cheeses.
Some controversy exists over the safety of cheese made by
traditional methods using unpasteurized milk and over how
pasteurization affects flavor.
