BUTTER DIRECTS 499 



entirely, the agencies which are known to contribute towards 

 the appearance of rancid flavor and odor in butter. Attention 

 to the following points will assist towards the prevention of 

 rancidity in butter. 



Prevention of Rancid Flavor. 1. Elimination ; of bacteria 

 and mold from butter. The fresher and sweeter the cream and 

 the greater its freedom from objectionable bacteria and mold 

 and from their products, and the freer the butter from curd, the* 

 better will such butter withstand decomposition which results 

 in rancidity. 



2. Proper pasteurization of the cream and thorough washr 

 ing of the butter with pure water greatly lessens the tendency 

 of butter to become rancid. Pasteurization destroys the germs 

 capable of producing rancid butter. Thorough washing removes 

 much of the curd and therefore reduces the necessary foq4 

 available for rancidity-producing microorganisms. Farm-made 

 butter usually develops rancid flavor and odor very rapidly, 

 because it is made from raw cream teeming with germlife and 

 usually contains excessive buttermilk. Storage butter made dur- 

 ing a pasteurization experiment under the direction of the author 1 

 did not develop rancidity when made from pasteurized cream; 

 raw cream butter when made from ungraded gathered cream 

 almost invariably became rancid, while raw cream butter made 

 from selected gathered cream did not show much rancidity in 

 storage. This emphasizes both, the value of pasteurization and 

 the importance of careful grading of cream. The housewife in 

 many European countries, who purchases a year's supply of cook- 

 ing butter (Schmelzbutter) melts and boils it until the curd, 

 water and other non-fatty constituents have settled out and the 

 fat has become clear. This fat is stored in a cool place (the 

 cellar) in crocks, covered w r ith parchment, and keeps almost in- 

 definitely (until used up) without showing signs of rancidity. 

 These illustrations emphasize that rancidity can be greatly de- 

 layed by removing germ life and the food on which micro- 

 organisms thrive. Efficient pasteurization, and thorough wash- 



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

 Cream, Produce Bulletin 208, 1918. 



