THE SWISS AND ITALIAN GROUPS 289 



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 com- 

 monly a provision for direct heating by fire which is 

 sometimes carried on a truck, and therefore can be with- 

 drawn when heating is sufficient. The steam-jacketed 

 kettle has replaced this earlier form to a large measure. 



