Pasteurization of Milk. 237 



In general two great classes of milk are recognized, namely, 

 raw milk and pasteurized milk. Under these general classes there 

 are different grades, as indicated in the report of the committee 

 on classification. 



Pasteurization. 



While the process of pasteurization is a matter which has at- 

 tracted a great deal of attention in recent years, the commission 

 has not entered into any discussion of its merits or demerits, but 

 has given it recognition in its classification as a process necessary 

 for the treatment of milk which is not otherwise protected against 

 infection. 



The commission thinks that pasteurization is necessary for all 

 milk at all times, excepting grade A, raw milk. The majority of 

 the commissioners voted in favor of the pasteurization of all milk, 

 including grade A, raw milk. Since this was not unanimous the 

 commission recommends that the pasteurization of grade A, raw 

 milk, be optional. 



The process of pasteurization should be under official super- 

 vision. The supervision should consist of a personal inspection 

 by the milk inspector. The inspections shall be as frequent as 

 possible. Automatic temperature regulators and recording ther- 

 mometers should be required and the efficiency of the process 

 frequently determined by laboratory testing. 



Pasteurizing Temperatures. 



The destruction of the chemical constituents of milk by heat 

 occurs at higher temperatures than those necessary for the destruc- 

 tion of the bacteria of infectious diseases transmissible by milk. 



The commission passed a resolution regarding the temperature 

 of pasteurization as follows: 



That pasteurization of milk should be between the limits of 140 F. and 155 F. At 

 140 F. the minimum exposure should be 20 minutes. For every degree above 140 F. the 

 time may be reduced by 1 minute. In no case should the exposure be for less than 5 

 minutes. 



In order to allow a margin of safety under commercial condi- 

 tions the commission recommends that the minimum temperature 

 during the period of holding should be made 145 F. and the hold- 

 ing time 30 minutes. Pasteurization in bulk when properly carried 

 out has proven satisfactory, but pasteurization in the final con- 

 tainer is preferable. 



It is the sense of the commission that pasteurization in the 

 final container should be encouraged. 



