PASTEURIZATION 129 



making pasteurization is understood to mean a brief 

 heating of the cream and whole milk to 80 to 85 C. 

 (176 to 185 F.), the purpose of which is to kill most 

 of the existing bacteria, in order to prevent those fer- 

 mentations of the cream which might cause the butter to 

 be of inferior quality. At the same time, pathogenic 

 micro-organisms (particularly tubercle bacilli) are made 

 harmless. In some places, ' ' pasteurized butter ' ' is made 

 solely for the latter purpose. 



In Denmark, on account of the danger of spreading 

 tuberculosis among animals, it is provided by law that 

 skim milk and buttermilk delivered from creameries to 

 be used as food for animals must have been heated to 85 

 C. (185 F.). In this connection, however, the law does 

 not mention pasteurization but, in practice, pasteurized 

 separator milk (or buttermilk) is understood to be milk 

 that has been subjected approximately to the above men- 

 tioned temperature and that does not react to Storch's 

 or to the guaiac tests. 



Since market milk is pasteurized especially in order 

 to render harmless any disease producing germs that 

 may possibly be present, and since the majority of con- 

 sumers are, doubtless, of the opinion that pasteurized 

 milk may be used with perfect safety without further 

 heating, it should be strictly required that market milk 

 sold as " pasteurized " shall have been subjected to a 

 sufficient degree of heat to kill with certainty all of the 

 pathogenic micro-organisms that are present. 



The pathogenic bacteria that are of importance in 

 this connection are the germs of tuberculosis, typhoid 

 fever, diphtheria, cholera and pest and pyogenic cocci 

 and the virus of foot-and-mouth disease. These have 

 been shown by recent investigations to be killed by mo- 

 mentary heating to 70 to 80 C. (158 to 176 F.) and 

 they die at a temperature of 65 C. (150 F.), if this 

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