MILK AND YIELD OF CHEESE 187 



(3) The amount of whey retained in cheese. 



THE RELATION OF FAT AND OF CASEIN 

 TO YIELD OF CHEESE 



Those constituents of the milk that are insoluble 

 and are present in suspension as solids or in emul- 

 sion, those that can be, for the most part, mechan- 

 ically held by the coagulated casein, furnish the 

 solid materials for cheese. They are: (i) Milk- 

 fat; (2) milk-casein; and (3) insoluble phosphates. 

 The fat and casein constitute so large a proportion 

 of these cheese-producing solids of milk that we 

 should not be far from the truth in saying that 

 only these two constituents of normal milk are 

 prominent in determining the yield of cheese. These 

 two constituents of milk form over 90 per cent of 

 the solid portion of cheese (cheese-solids) ; the only 

 other solids in cheese are comparatively small in 

 amount, consisting essentially (i) of the calcium 

 salts of phosphoric, lactic and citric acids; (2) of the 

 salt added in cheese-making; (3) of a small amount 

 of milk-albumin; and (4) of some milk-sugar, which 

 mostly disappears in a few days. 



The yield of cheese from milk varies as the 

 amount of fat and casein in milk vary, provided the 

 conditions of cheese-making are the same, includ- 

 ing under these conditions the quality of the milk 

 with reference to cleanliness (bacterial content), (p. 

 4). As a rule, when the percentage of fat in milk 

 increases, the percentage of casein also increases (p. 

 169) and the yield of cheese increases in proportion 

 to the increase of fat and casein. At this point, the 



