COMPARISON OF BEEF AND YEAST EXTRACTS. 5 



to considerable variation, depending on the per cent originally pres- 

 ent in the flesh of the animals from which the individual extract was 

 prepared, their absence in yeast extracts gives an excellent test for 

 distinguishing between the two products. In the flesh of the beef 

 all of the kreatin and kreatinin are present as kreatin, and a portion 

 of this is changed to kreatinin by the long-continued evaporation in 

 an acid medium to which the extracts are subjected. 



Hehner states that the kreatin and kreatinin content of meat 

 extracts averaged from 10 to 11 per cent when a sufficient amount 

 (25 cc) of picric acid was present. In the four samples of true beef 

 extract reported in Table 1, when 25 cc of picric acid were used, 

 the highest combined kreatin and kreatinin value obtained was about 

 8 per cent on the water-free and fat-free basis. The writer has 

 never obtained a higher value than this. 



The acidity figures, which were obtained by dissolving 1 gram of 

 the extract in 300 cc of distilled water and titrating with tenth- 

 normal sodium hydroxid, using phenolphthalein as the indicator, 

 are practically the same for the two kinds of extracts. 



All of these samples were tested for sugar by the copper reduc- 

 tion method, but none was found. On standing, a copper precipi- 

 tate appeared. In the ether extract of the yeast extracts an amor- 

 phous residue was left in the fat flask approximating 1 per cent of 

 the extract. The Salkowski reaction for cholesterol was applied to 

 an aliquot of the ether-soluble residue dissolved in chloroform, but 

 no reaction was obtained. In one or two samples of the beef extracts, 

 especially A. P. 796, a large number of crystals was left in the fat 

 flask. These crystals were more soluble in chloroform than was the 

 yeast ether-soluble residue, but likewise gave no cholesterol reaction. 

 Portions of both the meat and the yeast ether-extraction residues 

 were tested for phosphoric acid with negative results. 



The purin base results, obtained by the modified method of Schit- 

 tenhelm & show that the beef and yeast extracts contain practically 

 equal total amounts of these bases. Micko c has shown that adenin and 

 guanin predominate in yeast extracts and hypoxanthin and xanthin in 

 meat extracts. In a recent article Gamgee d states that the ingestion of 

 yeast extracts involves an enormous increase of purin bases as com- 

 pared with an ingestion of meat extracts. The figures he reports 

 are, purin base nitrogen of yeast extracts 0.646 per cent, of meat 

 extracts 0.433 per cent. Some recent figures reported by Chapman 



Pharm. J., 1907, 24 : 683. 



& U. S. Dept. Agr., Bureau of Chemistry Bui. 114, p. 41. 



c Zts. Nahr. Genussm., 1903, 6 : 781 ; 1904, 7 : 257 ; 8 : 225. 



d Brit. Med. J., August 22, 1908, p. 449. 



e Brit. Med. J., December 12, 1908, p. 1741. 



