The consistency of most cheeses changes dramatically when frozen. Consequently, food experts strongly advise against freezing cheese, especially of the softer and artisinal varieties. However, certain harder cheeses may stand up to freezing if the preparation style subsequent to thawing is less reliant on texture.
When cheese freezes, the water content located inside freezes as well, forming ice crystals that expand the volume of the cheese. This expansion causes the desired molecular structure of the cheese to break down, producing any number of undesirable results. These can include an increased leaky liquid content and a toughened, granular taste. If freezing sliced deli cheeses, thawing often causes the slices to clump or fuse together unappealingly.
The best cheeses to freeze are hard, grating varieties, such as Parmesan or Romano, or blocks of store-brand cheddar. Nonetheless, taste, if not texture, can still suffer from freezing some of these cheeses, with the addition of a burnt, metallic flavor. If it is unavoidably necessary to use previously frozen cheese, that cheese is best used in a preparation that requires melting. For example, frozen mozzarella should never be used in a salad, but could easily be used for pizza. Similarly, frozen cheese can be added to soups, sauces, sautés or casseroles without incident.