32 MEAT EXTRACTS. 



NITROGENOUS BODIES. 



Classes of Nitrogenous Constituents and General Methods of Separation. 



It is believed that the proteids are made up of molecules of extreme 

 complexity — hundreds of atoms of carbon, hydrogen, oxygen, and 

 nitrogen — but the arrangement of these atoms and their number 

 have not been definitely determined. Various proteid substances are 

 spoken of, for example, albumins and peptones, as pure chemical 

 substances, but it is impossible at present to prepare two specimens 

 of egg albumin exactly alike, and in the case of peptones even more 

 difficulty is encountered. Because certain nitrogenous bodies give 

 color reactions that are alike and exhibit a few points in common, 

 they are grouped together under a definite term. It is not surpris- 

 ing, therefore, that the methods for the separation of nitrogenous 

 bodies are far from satisfactory in many cases. 



Professor Mallet" says the following classes of the nitrogenous 

 constituents of food are commonly recognized as requiring separate 

 consideration : 



1. Proteids proper (by some called albuminoids), and their closely related deriva- 

 tives, trie proteoses and peptones. 



2. Gelatinoids or collagens, and allied substances immediately derived from them, 

 such as gelatin, chondrin, etc. 



3. Simpler amids, amido-acids, and allied substances, such as the asparagin, glu- 

 tamin, etc., of vegetable materials, and the "flesh bases" (kreatin, kreatinin, etc.) 

 of animal origin. 



4. Alkaloids, or amine-like compounds of well -determined basic character. 



5. Ammonia and its salts, 

 fi. Nitrates. 



To these, no doubt, should be added lecithin and analogous sub- 

 stances containing nitrogen, but closely allied to the fats. 



The average nitrogen content of the pasty or solid extracts usually 

 varies from 6 to 9 per cent. The nitrogen in the so-called meat juices 

 is subject to much greater fluctuation, depending largely on the con- 

 tent of solids. Although a high nitrogen content is not a guarantee 

 of the character or mode of manufacture of an extract, an average 

 nitrogen content is desirable. 



All nitrogen determinations were made by T. C. Trescot. 



Several new determinations were applied to the analysis of meat 

 products. These include the separation and estimation of the meat 

 bases by a modification of the Schjerning tannin-salt method, 6 the 

 determination of kreatin and kreatinin by the colorimetric method of 

 Folin, c the determination of xanthin bases by the method of Schitten- 

 helm/ the estimation of ammonia by the magnesium oxid method," 



« U. S. Dept. of Agr., Bureau of Chemistry, Bui. 54, page 7. 



b J. Amer. Chem. Soc, 1906, 12:1485. 



cZts. physiol. Chem., 1904, 41:223. 



^U. S. Dept. Agr., Bureau of Chemistry, Bui. 90, page 129. 



«U. S. Dept. Agr., Bureau of Chemistry, Bui. 107, page 9. 



