+276. Parmesan.+--One type of Italian cheese, however, the Parmesan, has become very widely known. In general the consuming trade does not discriminate between Parmesan, Grana and closely related forms. Parmesan is made in large cheeses which require one to three years for proper ripening; in texture it is very hard with small eyes or holes formed by very slow fermentation. Such cheeses are ripened in large storehouses in which hundreds and even thousands are brought together and cared for by experts. The surfaces of these cheeses are kept clean and free from insects by rubbing with linseed oil. So hard are these forms that the cheese-trier is not used in testing, but the texture of the surface is tested by pricking with an awl-like tool and the stage of eye-formation and associated ripening is determined by the sound given out when the cheeses are tapped with a hammer. When ripe, the cheeses of this group are used in cooking principally. The broken cheese is grated and added to macaroni, spaghetti and other cooked cheese dishes. Parmesan is usually made from partly skimmed-milk; the ratio of fat to protein in analysis runs from 1:2 to 3:4 in contrast to the normal relation of about 4:3 in whole-milk cheese. In water-content much variation is found, but ripe Parmesan is usually about 30 per cent water. Other members of the group are made with different amounts of skimming, some of them from whole milk. The group in general represents the requirements of cheese for the trade of warmer regions (see Mayo and Elling): (1) a low fat-content so incorporated that the cheese does not become greasy or oily in hot weather; (2) a water-content low enough to prevent rapid spoilage during the necessary exposure of handling under warm conditions. The equipment for Parmesan manufacture has more resemblance to that of the Swiss factory than the English and American cheeses. The milk is curdled in deep copper kettles (Fig. 57), below which there is commonly a provision for direct heating by fire which is sometimes carried on a truck, and therefore can be withdrawn when heating is sufficient. The steam-jacketed kettle has replaced this earlier form to a large measure. [Illustration: FIG. 57.--Parmesan cheese kettles.]