NITROGENOUS CONSTITUENTS OF COCOA. 039 



For percentages of theobromine in cocoa and cocoa preparations, see 

 tables of analyses given below ; for methods of quantitative determina- 

 tion, see methods of analysis given below. 



The commercial importance of theobromine at present offers no temp, 

 tation to remove it from cocoa preparations before placing them on the 

 market. 



Small percentages of caffeine have been found in cocoa beans, espe- 

 cially in the shells. It is separated from the theobromine by solution in 

 cold benzol, in which the theobromine is practically insoluble. Weig- 

 mann 1 reports 0.17 per cent in cocoa mass and 0.113 to 0.190 per cent in 

 cocoa shells ; Bell, 2 traces to 0.25 per cent in the bean and 0.33 per cent 

 in the shells. 



Nonalkaloidal nitrogenous substances. Stutzer 3 classifies the nitroge- 

 nous constituents of cocoa, as follows : 



(1) Nonproteids, substances soluble in neutral water solution in presence of 

 Cu(OH)i (theobromine, ammonia, and amido compounds). 



(2) Digestible albu:nen, insoluble in neutral water solution in presence of 

 Cu(OH) 2 , but soluble when treated successively with acid gastric juice and alkaline 

 pancreas extract. 



(3) Insoluble and indigestible nitrogenous substances. 



In the same article he writes as follows in regard to the food value of 

 the nitrogenous constituents of cocoa : 



The group of nitrogenous constituents is of great importance in all foods, espe- 

 cially their content of digestible albumen. Among the general public the opinion 

 is very widely extended that cocoa belongs to the very easily digestible foods. The 

 extremely favorable mechanical treatment is certainly such that the digestive fluids 

 have no considerable mechanical resistance to overcome in the assimilation of the 

 nutritive constituents of cocoa. On the contrary, the chemical reaction between 

 the solvent constituents of the digestive juices and the nitrogenous nutritive con- 

 stituents of cocoa can not be called an especially strong one. A large proportion of 

 these constituents, in spite of apparently favorable conditions, remain entirely in- 

 digestible, entirely worthless. I have already called attention to the slight digesti- 

 bility of the albuminous substances of cocoa, 5 and once illustrated their difficult di- 

 gestibility graphically in the Berliner Hygiene- Ausstellung. In the meantime, these 

 observations have been confirmed by investigations of H. Weigmann, which he un- 

 dertook on his own account. Weigmann found only 42 per cent of the nitrogenous 

 substances in cocoa to be digestible. 



1 Op. cit., note 8, p. 938 of this work. 



2 Bell, Analysis and Adulteration of Food. 



3 Zeitsch. f. angew. Chem., 1891, 368. 



