572 BIOI,OGICAI, PROPERTIES o$ BUTTER 



A substance is of a stable nature, and that it is neither destroyed, 

 nor its growth-promoting and curative effect lessened by heat, 

 saponification, or age. 



Butterfat boiled with live steam for several hours did not 

 lose its biological properties. This is important, because it 

 demonstrates conclusively, that the pasteurization of cream does 

 not rob the resulting butter of its growth-promoting and cur- 

 ative properties. Pasteurized cream butter is equally valuable 

 therefore from the dietary standpoint as raw cream butter. 



Butterfat or butter when completely saponified into a soap, 

 by admixture of alkali in excess, fully retains its growth-pro- 

 moting and curative properties. Butter soap so made, when 

 fed to the rats had the same biological effect as normal butter 

 or pure butterfat. This fact is important because it removes 

 every vestige of doubt that the reduction of the acid in sour 

 cream by the use of an alkali, as practiced in so-called neutral- 

 ization of sour cream, in no way destroys or weakens the 

 growth-promoting and curative properties of butter. Butter 

 made from sour cream that has been neutralized, has equal 

 dietary value as butter made from cream that was not neutral- 

 ized. 



Age does not change the biological value of butter. The 

 changes which butter undergoes in storage fail to deprive it 

 of its growth-promoting and curative effect. Butterfat held in 

 the cold and at room temperature, in the light and in the dark, 

 for ten months, when subsequently fed to rats which had 

 ceased to grow and had developed the characteristic sore eyes, 

 as the result of the absence in their diet of the fat-soluble A, 

 brought about resumption of growth to normal stature, and 

 recovery and healing of the eyes. The biological potency in all 

 samples of butterfat held in storage was retained and was equal 

 to that of fresh butter or fresh butterfat. This fact is impor- 

 tant, because it furnishes indisputable proof that storage butter, 

 relative to biological properties, is equally wholesome as fresh 

 butter. 



Other Sources of Fat-Soluble A. The only substances in 

 which the fat-soluble A has been found, other than butter and 

 butterfat, are the fat contained in the yolk of the egg, cod liver 

 oil, leaves of plants and the fat of the vital organs. 



