BUTTER-MAKING 249 



Two methods are in common use for pasteurization of cream 

 for butter-making. These are the "flash" method, in which a 

 high temperature (180 to 185 F.) is used, and the cream imme- 

 diately cooled down, and the " holding" or "vat" method, in 

 which a lower temperature is used, from 140 to 145 F., and 

 maintained for twenty to thirty minutes, after which the cream 

 is cooled. The experimental work conducted on the pasteuriza- 

 tion of cream for butter-making has not given entirely uniform 

 results. The general results obtained by the different methods 

 are summarized by Mortensen 1 as follows : 



" 1 . Pasteurization of either sweet or sour cream improves 

 the flavor of the resulting butter. 



" 2. Vat pasteurization seems to be the most efficient method 

 of sour cream pasteurization for improvement of flavor. 



"3. The per cent of butter-fat lost in the buttermilk when 

 churning raw cream is slightly greater than with cream pasteur- 

 ized while sweet. Reversed results were obtained when sour 

 cream was pasteurized. 



"4. The per cent of butter-fat lost in the buttermilk when 

 churning cream pasteurized while sour by the holding method 

 is greater than when churning cream pasteurized while sour by 

 the flash method. 



"5. The body of the resulting butter is slightly injured by 

 pasteurizing sweet cream by the holding method. 



"6. Butter manufactured from raw cream has higher moisture 

 content than butter manufactured from cream pasteurized by 

 the flash method. 



" 7. Prolonged heating of sour cream produces a higher mois- 

 ture-content in the resulting butter. 



"8. The per cent protein content of the resulting butter is not 

 influenced by the pasteurization of sweet cream, but is de- 

 creased by pasteurization of sour cream. " 



1 Iowa Bulletin No. 156, page 15. 



