44 MEAT EXTRACTS. 



tive reactions showed in 6 cases a slight trace and in 8 cases a very 

 strong reaction, indicating that the "liquor" from the parboiling of 

 corned beef was used in their preparation. (See p. 13.) 



UNDETERMINED MATTER. 



Under this head are included nonnitrogenous organic matter as 

 well as glycerol and carbohydrates. Glycerol has been considered 

 under a separate caption. The amount of undetermined matter 

 present depends on the mode of preparation of the extract; not 

 more than 10 per cent should be present in a meat extract. Inosite 

 and various amido acids, from which the nitrogen has been split off, 

 also constitute a portion of the undetermined matter. 



Several of the samples which gave a high per cent of undetermined 

 matter were tested for starch, reducing sugar, and glycerol. The 

 following qualitative results were obtained: 



Qualitative tests for starch, reducing sugar, and glycerol. 



The albumose and peptone products which are high in undeter- 

 mined matter, according to the tables, contain carbohydrates (starch 

 and sugars). In the case of several of the fluid meat extracts, or 

 juices, and in one or two solid extracts, glycerol is present. 



HISTORICAL NOTE ON NUTRITIVE VALUES. 

 GELATIN. 



It has long been known that gelatin is present in various amounts 

 in meat extracts. The collagen of the muscle on hydration yields 

 gelatin, and if the hydration be carried far enough soluble gelatin, 

 gelatoses, and gelatin peptones are found. Gelatin, while rich in 

 nitrogen, is not capable of keeping the body in nitrogenous equilib- 

 rium, since the nitrogen is not present in a form available to the body 

 as in all true proteids. This has lately been explained by Kaufl- 

 mann a on the ground that the gelatin molecule is lacking in the 

 tyrosin, cystin, and tryptophane groups and that by feeding these 

 amido bodies with gelatin animals are kept in nitrogenous equilibrium. 



KaufTmann states that one-fifth of the proteid of a ration can be 

 replaced by gelatin, but when used in large proportions the body is 



aPfluger's Arch., 1905, 109 :440. 



