Cheese is a
food made from
milk, usually of
cows, buffalos,
goats, or
sheep, by
coagulation. The milk is acidified, typically with a
bacterial culture, then the addition of the
enzyme rennet or a substitute (e.g. acetic acid or vinegar) causes coagulation, to give "curds and whey".
[1] Some cheeses also have
molds, either on the outer rind (similar to a
fruit peel) or throughout.
Hundreds of
types of cheese are produced. Their different styles,
textures and flavors depend on the origin of the milk (including the animal's diet), whether it has been
pasteurized,
butterfat content, the species of bacteria and mold, and the processing including the length of aging.
Herbs,
spices, or
wood smoke may be used as flavoring agents. The yellow to red color of many cheeses is a result of adding
annatto. Cheeses are eaten both on their own and cooked in 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 are acidified to a lesser degree by bacteria, which turn
milk sugars into
lactic acid, then the addition of rennet completes the curdling.
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.
Cheese has served as a hedge against famine and is a good travel food. It is valuable for its portability, long life, and high content of
fat,
protein,
calcium, and
phosphorus. Cheese is more compact and has a longer shelf life than the milk from which it is made.
Cheesemakers near a dairy region may benefit from fresher, lower-priced milk, and lower shipping costs. The long storage life of cheese allows selling it when markets are more favorable.