266 



SCIENCE AND PRACTICE OF DAIRYING. 



of its weight. The separation of the curd is effected, when the liquid 

 has become sufficiently sour, by simply warming at 37 to 50 C., or 

 by the addition of hot water. If the liquid be not sufficiently sour, 

 sour butter-milk is added before warming. At temperatures under 

 35 C. the separation is effected very slowly and very imperfectly, 

 and at temperatures over 50 C. the curd is found to be friable and 

 too dry. In the preparation of sour-milk cheese, it ought not to be 

 forgotten that the sour liquid acts upon metals, and that the cheese 

 may become poisoned if the curd be allowed to stand for a long time 



in bright copper kettles. For 

 this reason, heating should 

 only be conducted in copper 

 kettles plated with tin, and 

 the curd should be brought 

 into wooden vessels as soon 

 as separation is effected. 

 During the preparation of 

 numerous kinds of sour-milk 

 cheeses, the curd is kept for 

 some time before moulding, 

 and a species of fermentation 

 is allowed to go on in it. 

 During the ripening process, 

 everything depends on whe- 

 ther moulds are kept from 

 the cheese. 100 kilos, of skim- 

 milk or butter-milk, or a mix- 

 ture of skim-milk and butter- 

 milk, yield, according to 

 whether a greater or lesser 



amount of pressure is applied, 8 to 13 kilos. on an average 11 kilos. 

 of fresh curd, and 5 to 8*5 kilos, of perfectly ripened sour-milk 

 cheese. 100 kilos, of milk should produce 7'5 to 9'5 kilos, of fresh 

 sour-milk cheese, in addition to 3 to 3'5 kilos, of butter. All sour- 

 milk cheeses are salted in the vat, and many kinds have all sorts of 

 things added to them, especially herbs (zigerklee). The smaller fresh 

 sour-milk cheeses under *3 kilo, in weight suffer a distinct loss in 

 weight during ripening, which, when the cheeso becomes slightly ripe, 

 amounts to about 30 per cent, and when the cheese is quite ripe, to 

 from 35 to 50 per cent or more. These small cheeses are generally 



Fig. 76. Curd Mill. 



