Cooling and Aeration. 171 



Cooling.— All that was said in Chapter V. on 

 "market milk," in regard to cleanliness in di^awing 

 the milk, applies eqnally well to milk that is in- 

 tended for cheese making, bnt where milk is made 

 into cheese it is not necessary, nor, indeed, is 

 it desirable, that the lactic acid fermentations be 

 checked further than is necessary to allow the milk 

 to come into the cheese maker's hands in the best 

 condition. In cheese making, the fermentations of 

 the milk play a most important part, and while it 

 is not at present known just what fermentations are 

 necessary or most desirable, sufficient is known to as- 

 sure us that a certain amount of lactic acid is not 

 only desirable but necessary for the cheese making 

 process, and enough further is known that those fer- 

 mentations which attack the protein substances, and 

 result in the formation of strong flavors, taints and 

 gases, are all undesirable in cheese making. For 

 the purpose of cheese making, it is desirable that the 

 fat should separate from the other constituents of 

 the milk as little as possible, and to that end the 

 previous treatment of the milk should be such that 

 the separation of cream will be held back as much 

 as possible. One of the best means of doing this 

 is to cool the milk to the temperature of the air 

 while it is kept constantl}' in motion. This, be- 

 side helping to keep the cream mixed Avith the milk, 

 will also favor the escape of any volatile animal 

 products that may be present in the milk, known 

 under the collective name of animal odor, and 

 Avhich would otherwise impart objectionable flavors 

 to the cheese. 



