Issued November 15, 1910. 



United States Department of Agriculture, 



BUREAU OF CHEMISTRY Circular No. 62. 

 H. W. WILEY, Chief of Bureau. 



A COMPARISON OF BEEF AND YEAST EXTRACTS OF KNOWN ORIGIN. 



By F. C. COOK, 

 Section of Animal Physiological Chemistry. 



INTRODUCTION. 



Beef and other meat extracts of pasty consistency and various 

 fluid preparations of animal origin are extensively sold in the United 

 States, and while very few yeast extracts are manufactured in this 

 country at present, they are made quite extensively in Germany and 

 England. In judging of the quality of such products, the advantages 

 to be derived from a knowledge of the composition of beef and yeast 

 extracts prepared under known conditions are evident. The lack of 

 such analyses in the literature of the subject has led to this study. 



COMPOSITION OF LEAN BEEF AND OF YEAST. 



The flesh of lean beef, according to analyses made in this labora- 

 tory, when calculated to a fat-free basis, consists approximately of 

 77 per cent of water, 1 per cent of ash, 19.70 per cent of protein, and 

 1.30 per cent of nitrogenous extractives, in addition to which 1 per 

 cent of nonnitrogenous organic extractives are present. The analyses 

 of the fresh samples naturally vary with, the fat content. Approxi- 

 mately one-tenth of the total nitrogen is in the form of extractive 

 or amino nitrogen. The total nitrogen averages 3.30 per cent and 

 from 25 to 30 per cent of this is water soluble ; 0.025 per cent of the 

 nitrogen is calculated as ammonia nitrogen, using the magnesium 

 oxid method. The content of kreatin averages 0.30 per cent and the 

 acidity, calculated as lactic acid, 1 per cent. A large percentage of the 

 phosphorus and one-half of the sulphur is water soluble. The non- 

 nitrogenous organic extractives consist of glycogen, inosit, lactic acid, 



56768 Cir. 6210 



