220 SCIENCE AND PRACTICE OF DAIRYING. 



heating. This is done by raising the temperature of the contents 

 of the cheese vessels gradually, occasionally only a few degrees 

 above the coagulation temperature, but occasionally also to a higher 

 temperature, and in a few cases up to 75 C. In the preparation 

 of Cheddar in most American cheese factories, the curd is sub- 

 mitted to a peculiar treatment. The cut curd is left, either under 

 the whey, or after the whey has been removed, in a covered cheese 

 vessel, at a temperature not far removed from the coagulation 

 temperature, to lie until it has gained the proper degree of ripeness, 

 that is, until it possesses a certain sticky property and a sour 

 smell. The degree of ripeness is judged by testing with hot irons, 

 after the method introduced by L. M. Norton. This test is carried 

 out in the following way: An iron bar is made red-hot, and then 

 allowed to cool till it no longer shows redness in daylight. It is 

 then brought into contact with a small piece of the curd, and the 

 behaviour of this piece of curd is observed. If the curd cling to 

 the iron, and is drawn out, when the iron is moved away, in threads 

 which possess a length of from 1 to 2 centimetres, the proper degree 

 of ripeness has been reached. Evidence that the ripening has not 

 been carried on far enough is afforded by the curd not sticking to 

 the iron at all, or if the ripening has been carried too far, the curd 

 sticks in such a manner that long threads can be drawn. 



All processes which have to do with the contents of the cheese- 

 vat after the coagulation of the milk, and up to the process of 

 shaping the cheese, and all precautions which are taken in these 

 operations, should have as their object to maintain the curd of a 

 uniform composition. 



When the cheese is made in kettles, this last requirement can only be 

 properly carried out if the process be thoroughly understood. As soon 

 as coagulation has taken place, and the curd has become sufficiently firm, 

 the lid is removed from the kettle in order to commence cutting, flat 

 pieces of curd being scooped from the middle, where cooling goes on most 

 slowly, with a cheese-scoop, and laid round the edge of the kettle for the 

 purpose of keeping the curd in that part warmer. Thereupon, after the 

 curd has become sufficiently firm, it is cut with wooden cheese-knives in a 

 vertical direction, and then crosswise throughout the whole mass. The 

 curd is then slowly and continuously turned horizontally with the cheese- 

 ladle round the vat, and at the same time is being reduced to smaller 

 pieces. The cutting is effected by the sharp front-edge of the cheese- 

 scoop. When the curd has been reduced to a sufficiently small and firm 



