CAROTIN, THE PRINCIPAL YELLOW PIGMENT OF MILK FAT 449 



siderable ammonium sulphate, acidifying with acetic acid and bringing 

 to a boil. The precipitate was filtered off on a Bikhner funnel. The 

 layer of protein and fat had a golden-yellow color. The fat was 

 extracted with hot alcohol and ether. The golden-colored extract 

 was evaporated to dryness and the fat dissolved away with ether. 

 Alcohol was added and also 5 grams of KOH and saponification of 

 the fat allowed to, proceed on the steam bath for one-half hour. The 

 pigment was extracted from the diluted soap with ether. After 

 thorough washing with distilled water, the ether was evaporated care- 

 fully to dryness. The residue had a deep red color. It dissolved 

 at once in petroleum ether (b.p. 3O-5oC.). 



The pigment in this solution was now differentiated between the 

 petroleum ether and 80 per cent alcohol. In this way it was divided 

 into two portions which were about equal as far as could be detected 

 by the color of the two solutions, with perhaps slightly more color 

 in the 80 per cent alcohol. 



The pigment in the petroleum ether layer gave a blood-red colored 

 carbon-bisulphide solution which showed two absorption bands and 

 considerable end absorption. The measurements of these bands are 

 given in Table i. 



The pigment in the 80 per cent alcohol layer gave an orange- 

 colored carbon-bisulphide solution which showed three distinct absorp- 

 tion bands. The measurements of these bands are given in Table No. I. 



DISCUSSION OF RESULTS 



The results of the above experiments show very clearly that the 

 fat of human milk may be tinted with the same pigments found in 

 the fat of cow's milk. The relative proportion of carotin and 

 xanthophylls in human milk fat is much more nearly equal than in 

 the fat of cow's milk. This is not surprising when it is considered 

 that there is strong evidence that the xanthophylls are 'conveyed 

 through the body dissolved in fat, and when it is also considered 

 that fat plays a much greater part in human food than in the food 

 of the cow. i 



An especially interesting fact brought out by these brief studies 

 is that colostrum milk fat of the human is characterized by a very 

 high color just as is the case with the fat of the colostrum milk 

 from cows. In the experiment here reported, one of us had occasion 

 to observe that after about ten days the milk fat from the same woman 

 was very much lighter in color than during the first few days of 

 lactation. The milk was also observed at intervals for a period of 



