CAROTIN, THE PRINCIPAL YELLOW PIGMENT OF MILK FAT 447 



C. THE PIGMENTS OF HUMAN MILK FAT 



The discovery of the chemical and physiological relations of 

 the pigments of the fat of cow's milk to the carotin and xanthophylls 

 of plants naturally opens the question whether the pigments which 

 characterize the fat of other animals are of a similar character. 

 Opportunity was not afforded to study this question with any domestic 

 animals other than the cow. An opportunity, however,, was offered 

 to investigate the character of the pigments which sometimes give a 

 high color to the fat of human milk. 



The methods used for studying the character of the pigments 

 were the microscopic ones used in the preceding studies. The adsorp- 

 tion properties were not studied, however, the demonstration being 

 confined to the observation of the absorption bands and the relative 

 solubility properties. 



The fat from two samples of human milk from different sources 

 was used. Very little was known in regard to one of the samples, 

 it having been sent to the laboratory for analysis by a well-known 

 physician of the community. The other sample was taken by one of 

 us from a woman who had just given birth to a child, and represented 

 a portion of the milk of each day of the first few days of lactation. 

 Some further observations in regard to this sample will be reported 

 below. 



Experiment No. i 



This was the sample in regard to which very little was known, 

 with the exception that it was a bona fide sample of human milk. 

 The milk had a faint yellow tint. The volume of milk used was 

 approximately 125 c.cm. The milk contained about 3.5 per cent fat 

 and therefore yielded a little over 4 grams of fat. The fat was 

 obtained from the milk by precipitating it along with the proteins. 

 To do this the milk was acidified with acetic acid, a pinch of salt 

 added, and the milk brought to a boil. The precipitated proteins, 

 when filtered off, had a bright yellow color, due to occluded fat. 

 The fat was dissolved out with hot 95 per cent alcohol. 



After concentrating the alcoholic extract, the fat was saponified 

 by adding a small piece of KOH and boiling for about one hour. 

 The pigment was readily extracted from the soap by ether, after 

 dilution with water. ' The golden-yellow ether solution was washed 

 with water and evaporated to dryness. The residue dissolved at once 

 in carbon bisulphide with a red-orange color and in this solution 



