Cheese - Prepared from the curd precipitated from milk by rennet (containing the enzyme chymosin or rennin), purified chymosin, or lactic acid. Cheeses other than cottage and cream cheeses (see cheese, soft) are cured by being left to mature with salt, under various conditions that produce the characteristic flavour of each type of cheese. Although most cheeses are made from cow's milk, goat's and sheep's milk are used to make speciality cheeses, which are generally soft.
There are numerous variants, including more than a hundred from England and Wales alone (nine major regional cheeses: Caerphilly, Cheddar, Cheshire, Derby, Double Gloucester, Lancashire, Red Leicester, Stilton, and Wensleydale). Some varieties are regional specialities, and legally may be made only in a defined geographical area; others are defined by the process rather than the region of production. The strength of flavour of cheese increases as it ages; mild or mellow cheeses are younger, and less strongly flavoured, than mature or extra-mature cheeses.
Cheeses differ in their water and fat content and hence their nutrient and energy content, ranging from 50–80% water in soft cheeses (mozzarella, quark, Boursin, cottage; see cheese, soft) to less than 20% in hard cheese (Parmesan, Emmental, Gruyère, Cheddar; see cheese, hard) with semi-hard cheeses around 40% water (Caerphilly, Gouda, Edam, Stilton). They retain much of the calcium of the milk and many contain a relatively large amount of sodium from the added salt. Blue-veined cheeses (Danish blue, Gorgonzola, Stilton, Roquefort, etc.) derive the colour (and flavour) from the growth of the mould Penicillium roquefortii, during ripening. Holes (e.g. in Gouda, Emmental) arise during ripening from gases produced by bacteria.
(Source: Oxford Reference)