FORTY-SECOND ANNUAL CONVENTION 101 



method is heated to from 140 to 145 degrees F. at which tem- 

 perature it is held for twenty to twenty-five minutes, this being- 

 the condition under which all pathogenic organisms are destroy- 

 ed. 



From experimental work conducted at the Iowa Station 

 slightly better results were obtained by the vat method of pas- 

 teurization and the flavor of the butter made from pasteurized 

 cream scored higher and possessed better keeping qualities than 

 that made from raw cream. Pasteurized cream butter when 

 sweet cream was used in our experiments, contained slightly less 

 moisture, but the same amount of casein as did butter made 

 from raw cream. 



In the case of the sweet cream the body was not injured to 

 any extent by pasteurization and there was practically no differ- 

 ence between the body of the butter obtained from the pasteuriz- 

 ed cream and that obtained from raw cream. 



Pasteurization in the Gathered Cream Plant : When sour 

 cream is pasteurized both the continuous method and the vat 

 method of pasteurization may be employed. When pasteurizing 

 by the continuous method of flash heat, the cream should be 

 heated to a temperature of from 180 to 185 degrees F. From 

 the pasteurizer it is cooled immediately either to ripening or 

 churning temperature. It has been found advisable by a number 

 of creamery men to cool the cream immediately to churning tem- 

 perature, add a big starter and allow the cream to remain at 

 that temperature for a few hours before churning. Others have 

 found that butter made from, cream pasteurized in the vat 

 received a higher score on flavor, as an average, the gain being 

 about two points above the score of the raw cream butter and 

 over a point above the score on butter made from cream pasteur- 

 ized by the flash method. 



The casein content of the butter is lower when pasteurizing 

 sour cream than when pasturizing sweet cream. This is evi- 

 dently due to the fact that when sour cream is pasteurized the 

 casein in the presence of acid is acted upon by the heat forming 

 small hard casein particles. These particles are readily removed 

 from the butter with the buttermilk and wash water whereas in 



