Cheeses

Cheese is a fermented food derived from the milk of various mammals. Since humans began to domesticate milk-producing animals around 10,000 B.C., they have known about the propensity of milk to separate into curds and whey. As milk sours, it breaks down into curds, lumps of phosphoprotein, and whey, a watery, grey fluid that contains lactose, minerals, vitamins, and traces of fat. It is the curds that are used to make cheese, and practically every culture on Earth has developed its own methods, the only major exceptions being China and the ancient Americas.

The first cheeses were "fresh," that is, not fermented. They consisted solely of salted white curds drained of whey, similar to today's cottage cheese. The next step was to develop ways of accelerating the natural separation process. This was achieved by adding rennet to the milk. Rennet is an enzyme from the stomachs of young ruminants. A ruminant is an animal that chews its food very thoroughly and possesses a complex digestive system with three or four stomach chambers; in the United States, cows are the best known creatures of this kind. Rennet remains the most popular way of "starting" cheese, though other starting agents such as lactic acid and various plant extracts are also used.

By A.D. 100 cheese makers in various countries knew how to press, ripen, and cure fresh cheeses, thereby creating a product that could be stored for long periods. Each country or region developed different types of cheese that reflected local ingredients and conditions. The number of cheeses thus developed is staggering. France, famous for the quality and variety of its cheeses, is home to about 400 commercially available cheeses.

The next significant step to affect the manufacture of cheese occurred in the 1860s, when Louis Pasteur introduced the process that bears his name. Pasteurization entails heating milk to partially sterilize it without altering its basic chemical structure. Because the process destroys dangerous micro-organisms, pasteurized milk is considered more healthful, and most cheese is made from pasteurized milk today.

Raw Materials

Cheese is made from milk, and that milk comes from animals as diverse as cows, sheep, goats, horses, camels, water buffalo, and reindeer. Most cheese makers expedite the curdling process with rennet, lactic acid, or plant extracts, such as the vegetable rennet produced from wild artichokes, fig leaves, safflower, or melon.

In addition to milk and curdling agents, cheeses may contain various ingredients added to enhance flavor and color. The great cheeses of the world may acquire their flavor from the specific bacterial molds with which they have been inoculated, an example being the famous Penicillium roqueforti used to make France's Roquefort and England's Stilton. Cheeses may also be salted or dyed, usually with annatto, an orange coloring made from the pulp of a tropical tree, or carrot juice. They may be washed in brine or covered with ashes. Cheese makers who wish to avoid rennet may encourage the bacterial growth necessary to curdling by a number of odd methods. Some cheeses possess this bacteria because they are made from unpasteurized milk. Other cheeses, however, are reportedly made from milk in which dung or old leather have been dunked; still others acquire their bacteria from being buried in mud.

The unusual texture and flavor of processed cheese are obtained by combining several types of natural cheese and adding salt, milk-fat, cream, whey, water, vegetable oil, and other fillers. Processed cheese will also have preservatives, emulsifiers, gums, Gelatin, thickeners, and sweeteners as ingredients. Most processed cheese and some natural cheeses are flavored with such ingredients as paprika, pepper, chives, onions, cumin, car-away seeds, jalapeno peppers, hazelnuts, raisins, mushrooms, sage, and bacon. Cheese can also be smoked to preserve it and give it a distinctive flavor.

The Manufacturing Process

Although cheese making is a linear process, it involves many factors. Numerous varieties of cheese exist because ending the simple preparation process at different points can produce different cheeses, as can varying additives or procedures. Cheese making has long been considered a delicate process. Attempts to duplicate the success of an old cheese factory have been known to fail because conditions at a new factory do not favor the growth of the proper bacteria.

Preparing the milk

Small cheese factories accept either morning milk (which is richer), evening milk, or both. Because it is generally purchased from small dairies which don't pasteurize, this milk contains the bacteria necessary to produce lactic acid, one of the agents that triggers curdling. The cheese makers let the milk sit until enough lactic acid has formed to begin producing the particular type of cheese they're making. Depending on the type of cheese being produced, the cheese makers may then heat the ripening milk. This process differs slightly at large cheese factories, which purchase pasteurized milk and must consequently add a culture of bacteria to produce lactic acid.

Separating the curds from the whey

The next step is to add animal or vegetable rennet to the milk, furthering its separation into curds and whey. Once formed, the curds are cut both vertically and horizontally with knives. In large factories, huge vats of curdled milk are cut vertically using sharp, multi-bladed, wire knives reminiscent of oven racks. The same machine then agitates the curds and slices them horizontally. If the cutting is done manually, the curds are cut both ways using a large, two-handled knife. Soft cheeses are cut into big chunks, while hard cheeses are cut into tiny chunks. (For cheddar, for instance, the space between the knives is about one-twentieth of an inch [half a centimeter].) After cutting, the curds may be heated to hasten the separation from the whey, but they are more typically left alone. When separation is complete, the whey is drained.

Pressing the curds

Moisture must then be removed from the curds, although the amount removed depends on the type of cheese. For some types with high moisture contents, the whey-draining process removes sufficient moisture. Other types require the curds to be cut, heated, and/or filtered to get rid of excess moisture. To make cheddar cheese, for example, cheese makers cheddar, or finely chop, the curd. To make hard, dry cheeses such as parmesan, cheese makers first cheddar and then cook the curd. Regardless, if the curds are to be aged, they are then put into molds. Here, they are pressed to give the proper shape and size. Soft cheeses such as cottage cheese are not aged.

Aging the cheese

At this stage the cheese may be inoculated with a flavoring mold, bathed in brine, or wrapped in cloth or hay before being deposited in a place of the proper temperature and humidity to age. Some cheeses are aged for a month, some for up to several years. Ageing sharpens the flavor of the cheese; for example, cheddar aged more than two years is appropriately labeled extra sharp. Wrapping natural cheese

Some cheeses may develop a rind naturally, as their surfaces dry. Other rinds may form from the growth of bacteria that has been sprayed on the surface of the cheese. Still other cheeses are washed, and this process encourages bacterial growth. In place of or in addition to rinds, cheeses can be sealed in cloth or wax. For local eating, this may be all the packaging that is necessary. However, large quantities of cheese are packaged for sale in distant countries. Such cheeses may be heavily salted for export (such as Roquefort) or sealed in impermeable plastic or foil.

Making and wrapping processed cheese

Edible yet inferior cheeses can be saved and made into processed cheese. Cheeses such as Emmental (commonly called Swiss), Gruyere (similar to Swiss), Colby, or cheddar are cut up and very finely ground. After this powder has been mixed with water to form a paste, other ingredients such as salt, fillers, emulsifiers, preservatives, and flavorings are added. The mixture is then heated under controlled conditions. While still warm and soft, the cheese paste is extruded into long ribbons that are sliced. The small sheets of cheese are then put onto a plastic or foil sheet and wrapped by a machine.