APPLICATION OF REFRIGERATION TO HANDLING OF MILK. 65 



farms and upon the amount sold, it is necessary to have a consider- 

 able margin of safety in the capacity of the brine-storage tank. 



The application of refrigeration for dairy purposes depends upon 

 so many variables that it is practically impossible to treat the sub- 

 ject other than in a very general way. Each particular case demands 

 special study in order to obtain the best results, as there are many 

 methods of application according to the character of the business 

 and its particular phases. Generally speaking, however, the brine- 

 storage or congealing-tank system seems to be the one best adapted 

 for most plants, but the medium surrounding the evaporating coils 

 may be either a brine solution of sufficient strength not to freeze at 

 the ordinary working temperature, or it may be confined air, or it 

 may be milk brought in direct contact with the cooling surface of 

 pipes in which the refrigerant is evaporated. In many instances it 

 may be advisable to employ a combination of the different methods 

 in order to obtain the most satisfactory and efficient arrangement. 



As there are many methods of application of refrigeration to milk 

 and milk products, we will endeavor to differentiate as far as prac- 

 ticable between the various applications and discuss in a general way 

 what seems to be the one best suited for the purpose, and for this 

 reason the following classifications are made: 



1) Cooling milk on the farm. 



2) Maintaining temperatures during transportation. 



3) Receiving stations. 



4) Cooling milk in bottling plants: (a) pasteurizing plants; (6) 

 raw-milk plants. 



5) Refrigeration in creameries, general. 



6) Local creameries. 



7) Centralized creameries. 



8) Auxiliary creameries. 



9) Cream-buying stations. 



10) Market cream plants. 



COOLING MILK ON THE FARM. 



As the influence of both time and temperature combine to hasten 

 the development of bacteria in milk, it is obvious that it should be 

 cooled just as soon as possible after being drawn from the cow. As 

 has been previously pointed out, the cooling of fresh milk retards 

 the development of the bacteria, which produces fermentation in 

 milk, thereby in turn destroying the milk by causing it to sour. 

 The indications are that at 32° F. the development of bacteria is not 

 only retarded, but there is apparently an actual decrease in their 

 number when held at this temperature. The bacteria referred to, 

 however, are those found in milk, even though produced under f avor- 

 40083°— Bull. 98—14 5 



