566 FOOD VALUE OF BUTTER 



both bovine and human, and since these disease germs are 

 able to pass from infected milk and cream to the butter, and 

 maintain their virulence in butter for a considerable length of 

 time, regardless of salt content and low storage temperature 

 of the butter, the public welfare demands that milk and cream 

 used for buttermaking should be pasteurized. They further 

 clearly indicate that the temperature to which the milk or cream 

 should be heated, and the time of exposure necessary to destroy 

 all non-spore bearing disease germs should be, for the holding 

 process, not less than 145 F. for at least twenty and preferably 

 thirty minutes, and for the flash process not less than 180 F. 

 momentarily. 



In some states the pasteurization of cream for buttermak- 

 ing is compulsory, and the result of recent investigations indi- 

 cates that the great bulk, approximately 90% of all butter made 

 in American creameries is manufactured from pasteurized cream. 

 The processes of pasteurization used in the creameries are largely 

 those above prescribed or their equivalent, so that it is reason- 

 able to state that by far the majority of American factory-made 

 butter that enters state and interstate commerce may be con- 

 sidered safe from the standpoint of its freedom from virulent 

 disease germs and viruses. 



Most of the farm dairy butter, however, is made from raw 

 cream. If the cream from which it is made is free from disease 

 germs it is obviously equally safe as the creamery butter, but 

 similar to farm-peddled milk, which is rarely pasteurized, so 

 does farm butter offer no guarantee as to its safety to the con- 

 suming public. 



Digestibility and Caloric Value of Butter. 



Digestibility. The digestibility of butter, based on the 

 completeness of its utilization, or on its losses in digestion, is 

 very high, similar to that of products containing other fats in 

 about the same proportion. Thus Luhrig found the coefficient 

 of digestibility to be 97.86 per cent for butter and 97.55 per cent 

 for oleomargarine. 



The coefficient of digestibility of butterfat, or the percentage 

 consumed that is assimilated, as determined by various investi- 

 gators, and assembled by Langworthy and Holmes, is as follows : 



