THE SIGNIFICANCE OF YEASTS AND OIDIA IN 

 PASTEURIZED BUTTER 



F. W. BOUSKA AND J. C. BROWN 



The original object of pasteurization in butter-making was 

 to produce a better immediate flavor by controlling fermenta- 

 tions. The aim was to destroy undesirable microorganisms as 

 well as microorganisms whose effect is unknown. By means 

 of a pure culture of selected lactic acid bacteria (starters), 

 regulated temperatures, and the acid test, the desired flavor 

 was to be developed. In more recent times it was discovered 

 that pasteurization greatly improved the keeping quality of 

 creamery butter made from cream which had soured spontan- 

 eously on the farm. A considerable part of American butter 

 is now made from such cream. The succession of sweet milk 

 by sour cream as a source of creamery butter is a result of 

 economic conditions on the farm. Some farmers think that 

 the expense of hauling milk to the creamery every day is too 

 great. So they skim the milk at home and deliver the cream 

 twice a week in the winter and three times a week in the sum- 

 mer. The skim milk thus derived has the best feeding value 

 because it is warm and sweet. But the cream obtained by this 

 farm method is usually sour. It became our lot to design 

 methods of making butter from spontaneously soured cream 

 and to overcome butter defects that sometimes occur here. 

 While our experience, investigations, and results apply prin- 

 cipally to sour cream, it will be seen that in some respects a 

 general application can be made. 



Butter which has a good flavor when churned but develops 

 a bad flavor at low temperatures within one month has poor 

 keeping quality. Properly made pasteurized butter scoring 

 90 will, in current commerce, remain eatable to the last morsel. 

 In cold storage it scores 89 to 90 at the end of seven to ten 

 months. We have known churnings of butter to score 90 at 

 the end of eighteen months. 



