CAROTIN, THE PRINCIPAL YELLOW PIGMENT OF MILK FAT 443 



Tube 7. Five cc. of neutral solution of pancreatin. 



Tube 8. Five cc. of neutral pancreatic extract. 



Tube 9. Five cc. of neutral pancreatic solution plus 5 cc. of fresh 

 bile. 



Tube 10. Five cc. of neutral pancreatic extract plus 5 cc. of bile. 



The pepsin, trypsin and pancreatin were Merck's U. S. P. prepara- 

 tions. 



A set of ten' tubes was also prepared containing equal portions of 

 the xanthophylls of yellow corn. 1 



The following results were obtained. Carotin: Bleaching oc- 

 curred only in the tubes containing neutral and alkaline pancreatic 

 extracts. In the same tubes plus bile there was no decoloration. 

 The bile had no solvent action on the carotin, which was in marked 

 contrast to the xanthophylls, as noted below. Xanthophylls : The pig- 

 ments in tubes I, 3 and 4 were largely decolorized at the end of the 

 second day, while those in tubes 2, 7 and 8 retained their color after 

 the fifth day. No observations could be made on the tubes containing 

 bile until the fifth day on account of the fact that the bile had com- 

 pletely dissolved the pigments as soon as it was added. The pigments 

 were examined by desiccating the contents of the tubes with plaster 

 of Paris and extracting with ether. Marked bleaching had occurred 

 in all the bile tubes. Corn Xanthophylls : There was marked destruc- 

 tive action of these pigments in all the tubes except those containing 

 bile. The corn xanthophylls, like the xanthophylls from the alfalfa, 

 were readily soluble in bile. 



The most significant feature of the above results is the marked 

 difference in the solubility of carotin and xanthophylls in bile, the 

 surprising result being the very slight solubility of the carotin. This 

 was confirmed quantitatively using carotin from another source and 

 the bile from several different cows. The results are given in Table i. 

 The carotin used was a freshly prepared ether solution of carotin from 

 the carrot. Equal volumes of this solution were evaporated at a low 

 temperature and the residues treated with 10 cc. of bile from each of 

 four cows. After standing for several days with frequent shaking 

 the bile was filtered and 5 cc. of the filtrate desiccated with plaster 

 of Paris. This was extracted with ether until colorless. The extract 

 in each case was concentrated to a low volume, made up to 12.5 cc. 

 with absolute alcohol, and the color of the solution measured in the 

 Lovibond Tintometer. 



1. This was the unsaponifiable pigment of the corn which was more 

 soluble in 80 per cent alcohol than in petroleum ether. 



