Cheese is a generic term for a diverse group of milk-based food products. Cheese is produced throughout the world in wide-ranging flavors, textures, and forms.
Cheese consists of proteins and fat from milk, usually the milk of cows, buffalo, goats, or sheep. It is produced by coagulation of the milk protein casein. Typically, the milk is acidified and addition of the enzyme rennet causes coagulation. The solids are separated and pressed into final form. Some cheeses have molds on the rind or throughout. Most cheeses melt at cooking temperature.
Hundreds of types of cheese are produced. Their styles, textures and flavors depend on the origin of the milk (including the animalâ€™s diet), whether they have been pasteurized, the butterfat content, the bacteria and mold, the processing, and aging. Herbs, spices, or wood smoke may be used as flavoring agents. The yellow to red color of many cheeses is from adding annatto.
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 is valued 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 milk. The long storage life of some cheese, especially if it is encased in a protective rind, allows selling when markets are favorable.
Strict followers of the dietary laws of Islam and Judaism must avoid cheeses made with rennet from animals not slaughtered in a manner adhering to halal or kosher laws. Both faiths allow cheese made with vegetable-based rennet or with rennet made from animals that were processed in a halal or kosher manner. Many less-orthodox Jews also believe that rennet undergoes enough processing to change its nature entirely, and do not consider it to ever violate kosher law. As cheese is a dairy food under kosher rules it cannot be eaten in the same meal with any meat.
A study by the British Cheese Board in 2005 to determine the effect of cheese upon sleep and dreaming discovered that the effect of cheese on sleep was positive. The majority of the 200 people tested claimed beneficial results–the cheese promoting good sleep. Six cheeses were tested and the findings were that the dreams produced were specific to the type of cheese. None of the cheeses tested were found to induce nightmares. Cheese contains tryptophan, an amino acid that has been found to relieve stress and induce sleep.