cheese

Cheese is a dairy product, derived from milk and produced in wide ranges of flavors, textures and forms by coagulation of the milk protein casein [酪蛋白]. It comprises proteins and fat from milk, usually the milk of cows, buffalo, goats, or sheep. During production, the milk is usually acidified and the enzymes of rennet [凝乳] (or bacterial enzymes with similar activity) are added to cause the milk proteins (casein) to coagulate. The solids (curd) are separated from the liquid (whey) and pressed into final form. Some cheeses have aromatic molds on the rind [皮], the outer layer, or throughout. Most cheeses melt at cooking temperature. If a liquid coagulates, or something coagulates it, it becomes thick and almost solid.

Cream is a dairy product composed of the higher-fat layer skimmed from the top of milk before homogenization. In un-homogenized milk, the fat, which is less dense, eventually rises to the top. In the industrial production of cream, this process is accelerated by using centrifuges [离心机] called "separators". In many countries, it is sold in several grades depending on the total butterfat content. It can be dried to a powder for shipment to distant markets, and contains high levels of saturated fat. If something is homogenized, it is changed so that all its parts are similar or the same, especially in a way that is undesirable.

酪 lào 用动物的乳汁做成的半凝固食品或用果实做的糊状食品。

Over a thousand types of cheese exist and are currently produced in various countries. Their styles, textures and flavors depend on the origin of the milk (including the animal's diet), whether they have been pasteurized, the butterfat content, the bacteria and mold, the processing, and how long they have been aged for. Herbs, spices, or wood smoke may be used as flavoring agents. The yellow to red color of many cheeses is produced by adding annatto [胭脂树红]. Other ingredients may be added to some cheeses, such as black pepper, garlic, chives [细香葱] or cranberries. A cheesemonger, or specialist seller of cheeses, may have expertise with selecting the cheeses, purchasing, receiving, storing and ripening them. Annatto is a plant. The seed, leaf, and root are used to make medicine.

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 [乳酸], then the addition of rennet completes the curdling. Vegetarian alternatives to rennet are available; most are produced by fermentation of the fungus Mucor miehei [米赫毛霉], but others have been extracted from various species of the Cynara thistle [菜蓟] family. Cheesemakers near a dairy region may benefit from fresher, lower-priced milk, and lower shipping costs.

Cheese is valued for its portability, long life, and high content of fat, protein, calcium, and phosphorus [磷]. Cheese is more compact and has a longer shelf life than milk, although how long a cheese will keep depends on the type of cheese. Hard cheeses, such as Parmesan, last longer than soft cheeses, such as Brie or goat's milk cheese. The long storage life of some cheeses, especially when encased in a protective rind, allows selling when markets are favorable. Vacuum packaging of block-shaped cheeses and gas-flushing of plastic bags with mixtures of carbon dioxide and nitrogen are used for storage and mass distribution of cheeses in the 21st century.

Cheese is an ancient food whose origins predate recorded history. There is no conclusive evidence indicating where cheesemaking originated, whether in Europe, Central Asia or the Middle East, but the practice had spread within Europe prior to Roman times and, according to Pliny the Elder, had become a sophisticated enterprise by the time the Roman Empire came into being. A 2018 scientific paper stated that the world's oldest cheese, dating to approximately 1200 BCE (3200 years before present), was found in ancient Egyptian tombs.

In 2014, world production of cheese from whole cow milk was 18.7 million tonnes, with the United States accounting for 29% (5.4 million tonnes) of the world total followed by Germany, France and Italy as major producers. During 2015, Germany, France, Netherlands and Italy exported 10-14% of their produced cheese. The United States was a marginal [small or not very important] exporter (5.3% of total cow milk production), as most of its output was for the domestic market. France, Iceland, Finland, Denmark and Germany were the highest consumers of cheese in 2014, averaging 25 kg (55 lb) per person.

There are many types of cheese, with around 500 different varieties recognized by the International Dairy Federation, more than 400 identified by Walter and Hargrove, more than 500 by Burkhalter, and more than 1,000 by Sandine and Elliker.

References

1. Sandine, W.E. & Elliker, P.R., 1981. J. Agr. Food Chem. ,18, 557.
2. Walter, H.E. & Hargrove, R.C., 1972. Cheeses of the World. Dover Publications Inc., New York.

六级/考研单词: dairy, derive, flavor, texture, comprise, buffalo, goat, bacteria, liquid, mold, outer, melt, lotion, compose, skim, dense, accelerate, powder, saturate, homogeneous, herb, spice, ingredient, pepper, expertise, ripe, medicare, vinegar, lemon, vegetation, alternate, extract, calcium, compact, vacuum, parcel, carbon, dioxide, nitrogen, accord, elder, million, unite, import, consume, federation