218 



OF PASTEURIZATION 



the milk and cream to become profusely contaminated with 

 them through diverse channels, such as the air, the coating of 

 the cows, the bedding, the utensils, the milker. 



Additional contamination and possible spore formation re- 

 sults, from storing the cream in places where these undesirable 

 germs are prone to abide, such as poorly ventilated cellars, 

 etc., and where the cream is held long before it goes to the 

 creamery, as is often the case during the winter season. 



Effect of Pasteurization on Per Cent Fat Lost in Buttermilk. 



It is the general opinion that sour pasteurized cream does 

 not churn out as exhaustively as raw cream, and that butter- 

 milk from sour pasteurized cream churnings tends to show a 

 relatively high butterfat test. The average per cent fat in the 

 buttermilk of 104 churnings made from raw and pasteurized, 

 sour cream is shown below. 1 



Table 38. Per Cent Fat in Buttermilk from Raw Cream and 

 from Pasteurized Cream Churnings. 



The above figures do not show an appreciable difference 

 in the exhaustiveness of churning between raw and pasteurized 

 cream. While the raw cream buttermilk contained the least 

 amount of fat, the pasteurized cream buttermilk contained but 

 very little more fat. The difference in the fat content of the butter- 

 milk between the three different processes of pasteurization 

 used, also is very slight. 



In order to detect the effect of acidity of the cream on 

 the per cent fat in the buttermilk the 104 churnings were 

 grouped into churnings which at the time of pasteurization 

 contained .5 per cent acid and above, and churnings which at 

 the time of pasteurization contained less than .5 per cent acid. 

 These results are averaged in the following table. 



1 Hunziker, Spitzer and Mills. The Pasteurization of Sour, Farm -Skimmed 

 Cream for Buttermakingr, Purdue Bulletin, No. 203, 1917. 



