CASEIN 223 



the curd is broken into small chunks and piled on a drain- 

 ing table or rack covered with coarse cloth. Here the 

 whey and acid are washed out by streams of cold water. 

 The curd is then allowed to drain for two or more hours 

 until it becomes dry enough to be ground. Or it may be 

 placed in a press similar to an upright cheese press and 

 left there over night. The next morning the curd is passed 

 through a curd mill, such as is used in the manufacture 

 of cheddar cheese, and ground into small pieces. 



The curd is then placed upon drying trays, which con- 

 sist of coarse cloth stretched over a wooden frame. These 

 trays of curd are placed in the drier and left there until 

 the pieces of curd are quite dry and horny. The drier 

 may be either of the horizontal or vertical type. In both 

 cases it consists of a heated space in which the trays are 

 placed in tiers. At one end, or at the bottom of the drier, 

 is a power-driven fan that forces a current of air over a 

 hot radiator and thence to the trays of curd. A tempera- 

 ture of about 120 F. is maintained for ,about twenty- 

 four hours. 



At the end of this time the curd is dry and is. taken 

 from the trays, put into sacks holding about one hundred 

 pounds each, and shipped. At this stage the curd is in 

 small, yellowish white, irregular lumps. If the curd is 

 not thoroughly washed before drying, the presence of milk 

 sugar and heat will cause a discoloration and a flinty 

 appearance of the curd. This greatly lessens its solu- 

 bility and commercial value. 



One hundred pounds of skim milk will yield about 3^ 

 pounds dried casein, which contains about twelve per 

 cent of moisture. For this dry curd the casein companies 

 pay about seven cents per pound, which is equivalent to 

 24.5 cents per 100 pounds of skim milk. 



