316 MisoOtfi;A^k.^i>; STA: RESEARCH BULLETIN No. 9. 



oleomargarin manufacturers have also recognized the value of color 

 and, so far as the law has permitted, have made a practice of coloring 

 oleomargarin in imitation of butter. When the law placed a tax on 

 artificially colored oleomargarin, or in some cases prohibited it entirely, 

 the manufacturers began using only the highest colored beef fats 

 that could be bought or mixed the oleomargarin with butter having 

 a high natural color, in order to produce the color they sought. 



The Pigment of the Butter Fat as a Factor in the Coloration of Milk. 



The more or less yellow color of cows' milk which is especially 

 evident in the cream and butter has not been attributed in all cases 

 to the same pigment. On the one hand a few authors have stated 

 that the pigment of butter is manifested in the familiar yellow color 

 of milk whey. This view originated with Blyth l who called the whey 

 pigment lactochrome and the view has found its way into a number 

 of texts. On the other hand a larger number of authors have ignored 

 the whey pigment and considered the lipochrome-like pigment of the milk 

 fat to be the only factor causing the yellow color of cream and butter. 



The investigations which were carried on in this laboratory have 

 been the first to point out that the whey pigment and the butter fat pig- 

 ment are not identical but are distinct substances ; and that both are of 

 importance in causing the yellow color of milk. The pigment of the 

 butterfat is the more important of the two, however. The pigment 

 of the whey is of secondary importance, and is of an entirely different 

 nature. Its probable identity with urochrome, the specific urinary pig- 

 ment, has recently been shown by one of us. 2 



Object of the Present Investigations. 



The present investigations were undertaken primarily to study the 

 chemical nature of the yellow butterfat pigment and to classify it from 

 a scientific standpoint. At the same time information was gathered 

 with the hope of ascertaining to what extent the generally accepted 

 views concerning the color of milk fat are correct in order to establish 

 a scientific basis for the subject which would be of value to those 

 interested in the handling of dairy products in a commercial way. 



In the principal part of the investigation it was sought; (i) to 

 show the chemical and if possible the physiological relation of the 

 butter fat pigment to similar animal pigments such as the 



1. A. W. Blyth, "Foods. Their Composition and Analysis" Text, 4th 

 Edition 1896, p. 239. 



2. Lactochrome: The Yellow Pigment of Milk Whey, etc., by Leroy S. 

 Palmer and Leslie H. Cooledge. Missouri Agricultural Experiment Station 

 Research Bulletin No. 13;; Jour. Biol. Chem. XVII, p. 251 (1914). 



