STATUS OF PASTEURIZATION OF MILK. 



TABLE 3. Approximate quantity of in ilk pasteurized in various cities as shown 

 &*/ returns from questionnaire scut in 1921 Continued. 



The flash process consists in heating rapidly to the pasteurizing 

 temperature, then cooling quickly. In this process the milk is heated 

 from 30 seconds to 1 minute only, usually at a temperature of 160 

 F. or above. In view of the previously mentioned requirements for 

 pasteurized milk this process should not be considered suitable for 

 proper pasteurization. Several cities now prohibit the use of the 

 flash process for the pasteurization of milk. 



In the holder process the milk is heated to temperatures of from 

 140 to 150 F. and held for approximately 30 minutes, after which 

 it is rapidly cooled. Sometimes the milk, instead of being held at a 

 certain temperature in one tank for 30 minutes, is merely retarded 

 in its passage through several tanks or other retarding device so that 

 the length of time required for the milk to pass through is about 30 

 minutes. In such cases, however, there is not always assurance that 

 all the milk is held for the desired time. The holder process has 

 almost entirely replaced the flash process, and is the one most used 

 in this country. 



Pasteurization in bottles is the latest development of the process 

 to be used on a practical scale. This process, as first practiced, con- 

 sisted in putting the raw milk into bottles with water-tight seal caps, 

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