Cheese

(food engineering) A food produced from milk that has been clotted by acid or rennet to form a curd which is cut, shaped, pressed, and salted or brined.
(textiles) Tube of spun yarn to be put on a warp beam for weaving.

A product of milk, selectively concentrated from major milk components. It is generally rich in flavor and contains high-quality nutrients. There are many varieties of cheese, all produced in the following general manner. Raw or pasteurized milk is clotted by acid, rennet, or both. The curd is cut and shaped into the special form of the cheese with or without pressing. Salt is added, or the cheese is brined after pressing.

Acid is produced during manufacture of cheese by fermentation of the milk sugar, lactose. This fermentation is initiated by the addition of a culture of specially selected acid bacteria (starter culture) to the milk. Acid production in cheese curd retards growth of bacteria that cause undesirable fermentations in cheese. Moreover, it favors the expulsion of the whey and the fusion of the curd particles. Fresh cheese (cottage or cream cheese) does not require any ripening, and it is sold soon after it is made. Other varieties of cheese are cured or ripened to obtain the desirable consistency, flavor, or aroma. The flavor and aroma of cheese are obtained by a partial breakdown of mild proteins and fat by the action of microbial, milk, and rennet enzymes. In hard varieties (Cheddar, Gouda, Edam, Emmentaler or Swiss, and provolone) this is done by the microorganisms in the interior of cheese; in semisoft or soft types (Limburger, Camembert, and Roquefort) by the organisms on, or in contact with, the surface of cheese.

Processed cheese is produced from cheeses of different ages by blending. The mixture, melted with the aid of emulsifying salts (citrates and phosphates), is packed in sealed containers (tins, paperboard, foil, or plastic). Few bacteria other than spore-formers survive the heat treatment. No substantial growth of flora occurs in well-preserved process cheese, but spoilage by anaerobic spore-formers may occur.

Key materials for cheesemaking include fresh or precultured milk, cultures, milk-coagulating enzyme preparations, special microorganisms, salt, and beta carotene or annatto color. The amounts used and the manner in which these materials are applied strongly influence the cheese character. Cheese may be made from the milk of the cow, sheep, goat, water buffalo, and other mammals, but the milk of the cow is most widely used despite some limitations. Sheep milk and water buffalo milk generally give more flavor to the cheeses, and the color is uniformly white because of a lack of carotene in such mammalian milks, but they are more expensive to make into cheese.

Two major classes of cheeses exist, fresh and ripened. Fresh cheeses are simpler to make than ripened, are more perishable, and do not develop as intense flavors, but give a mild acid, slightly aromatic flavor and soft, smooth texture. Three basic groups characterize fresh cheese types: group I—ricotta and Broccio; group II—cottage, Neufchatel, and cream; and group III—mozzarella. Most ripened cheeses are contained in one of six basic groups. The characteristic cheeses in each group include: group I—Cheddar and Monterey; group II—Swiss (Emmentaler) and Gruyère; group III—Edam and Gouda; group IV—Muenster, brick, and Limburger; group V—provolone; and group VI—Camembert, Brie, and bleu.

Processed cheese is made from natural types. Nearly any natural cheese can be processed, except that for blue cheese technical difficulties cause blackening of the blue mold due to the high heat. Processed cheese is produced by grinding selected lots of natural cheese and adding cream, color, salt, and emulsifying agents. Processed cheese foods and spreads are made similarly, but include more water and less protein, fat, and other solids. See also Milk.