148 Dairy Bacteriology. 



chilled to 48 F. for about two hours before churning. 1 It 

 is also essential that the heated cream should be quickly 

 and thoroughly chilled after being pasteurized. 



The Danes, who were the first to employ pasteurization 

 in butter-making, used, in the beginning, a temperature 

 ranging from 158 to 167 F., but owing to the prevalence 

 of such diseases as tuberculosis and foot-and-mouth disease, 

 it became necessary to treat the milk so as to thoroughly 

 destroy the virus of the disease. This can be done by mo- 

 mentarily heating the same to the temperature of 185 F., 

 and this temperature is now generally employed. With 

 the use of this higher temperature the capacity of the pas- 

 teurizing apparatus is considerably reduced, as not more 

 than one-half to two-thirds as much milk can be handled 

 at 185 as at 158 F. 



When the system was first introduced in Denmark, two 

 methods of procedure were followed: the whole milk was 

 either heated before separation, or the cream was pasteur- 

 ized afterwards, the skim milk being treated separately. 

 At the present time the latter system is gaining grou'nd. 



The present law makes it compulsory to heat all skim 

 milk to 185 F. to avoid the dissemination of the diseases 

 previously mentioned. 



Apparatus for pasteurizing. As it is not necessary to 

 heat the milk or cream for butter-making under such a 

 narrow range of conditions as when designed for direct con- 

 sumption, it is permissible to employ machinery that be- 

 longs to the continuous-flow type. These pasteurizers have 

 a large capacity and it is possible to handle in them several 

 thousand pounds per hour. The majority of apparatus for 

 this purpose has originated in Denmark and Germany. 



* N. Y. Prod. Rev., October, 1899. 



