THE CHEMISTRY OF CHEESE MAKING 99 



loss occurs from cheese becoming unsound during 

 the curing process, and larger yields of cured cheese 

 are obtained from a given amount of milk. In the 

 cold curing of cheese the fermentation changes are 

 brought about entirely by the action of the soluble 

 ferments or enzymes of the milk. It is mainly a 

 digestion process, the changes taking place being 

 similar to those which occur in the first stages of 

 the digestion of the proteids in the stomach. The 

 acids produced unite with the casein, forming more 

 soluble and digestible products. Van Slyke, in his 

 studies on cheese making, states that lactic acid 

 forms with casein two compounds, paracasein and 

 paracasein monolactate, which contains half as much 

 acid as paracasein. 



Since both tlie insoluble or organized ferments and 

 the enzyiiius of milk take an important part in the 

 manufacture and curing of the product, it is highly 

 important that the milk be handled in the most 

 cleanly way possible, so as to reduce the germ con- 

 tent of the milk and prevent the formation of objec- 

 tionable flavors and products in the cured cheese. 

 Attention should be given to the sanitary condition 

 and surroundings of both the creamery and cheese 

 factory, as any unsanitary condition may afPect the 

 quality of the product. 



91. The Cheese Yield of Milk. — Since the per- 

 centage of casein to fat varies in different milks, it 

 follows that the cheese yield of milk is not directly 

 proportional to its fat content. Milks of the high- 



