The basic ingredient for cheese is milk usually derived from cows, sheep or goats, although the milk of yak, reindeer, camels and mares are also used in local cheese operations. First the milk is allowed to sour. Once the milk has sufficiently coagulated, the remaining liquid, or whey, is drained off. If only a little whey is drained, the cheese will be a soft cheese, like Brie. If all of the whey is removed from the curds, the cheese will be a hard cheese, like Parmesan.
Cheese makers vary the curd-whey ratio to produce a variety of cheese textures.
Once the curd consistency has been determined, the mixture is heated, squeezed, twisted, pulled or kneaded to refine the cheese's texture. Provolone, for example, is stretched and kneaded resulting in its more elastic texture. Mozzarella curds are chopped and shredded, thrown in hot water, kneaded and stretched, cooked in hot water once again, then shaped and thrown in cold water for preservation. When the cheese maker has achieved his desired consistency, the curds are patted into cheese molds and salted. The most important stage in cheese production is the ripening stage.