Cream and Factory By -Products. 123 



121. Whey. This by-product of cheese-making also 

 has considerable value for feeding purposes. Like sep- 

 arator skim-milk, it is drawn at a temperature that 

 greatly favors bacterial development. Compared with 

 the germ content of the raw milk, whey possesses fewer 

 organisms than skim- milk or buttermilk kept under sim- 

 ilar conditions, as a larger part of the bacteria present in 

 the milk are caught in the coagulated curd. The pres- 

 ence of these in whey, if left to cool naturally, soon sours 

 the product, as the milk-sugar is further converted into 

 various acids. Both whey and skim-milk for feeding 

 purposes should be carefully handled in order to get the 

 most out of them. If the ferments are allowed to develop, 

 the sugar is changed into various acids, the albumen un- 

 dergoes putrefactive changes, and much of the feeding 

 value is lost. 



122. Treatment of whey and skim-milk tanks. 

 The vats for factory by-products are often made of wood; 

 consequently, they are difficult to clean thoroughly, even 

 if that procedure is attempted. If not carefully cleansed 

 and sterilized by steam each day, the particles of milk or 

 whey that adhere to the walls, quickly sour, and so infect 

 the material that is stored in the vat on the succeeding 

 day. In this way the vat becomes a center of bacterial 

 infection. Often, too, this already contaminated waste 

 product is allowed to stand in cans after it is taken back 

 to the farms until it is thoroughly soured. Such fer- 

 mented food has only a minimum value, as much of its 

 nutritive worth is gone. Vats for these by-products 

 should be constructed from galvanized iron and arranged 

 to empty by gravity. The vats and supply pipes should 

 be carefully cleaned each day as much as any other part 

 of the factory. 



The trouble arising from sour whey and sour milk is 



