Cheese is a food made from milk , usually the milk of cows , buffalo , 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".  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. (MORE)