MEAT AND MEAT PRODUCTS. 11 



age of meat fiber or coagulated proteids. (In case the connective tissue is deter- 

 mined, a corresponding correction must be made in the percentage of coagulated 

 proteids.) 



(c) DETERMINATION OF CONNECTIVE TISSUE. 



Extract 10 grams of the sample with cold water as directed above, then boil the 

 exhausted residue repeatedly with about 100 cc of water until the total extract 

 amounts to about 1 liter. Filter the extract, concentrate by evaporation, and deter- 

 mine the nitrogen content. Multiply the nitrogen so obtained by 5.55 for the per- 

 centage of nitrogenous substances of connective tissue. 



(d) DETERMINATION OF COAGULABLE PROTEIDS (FOR UNCOOKED MEAT ONLY). 



Almost neutralize the filtrate from the coagulated proteids, leaving it still faintly 

 acid, boil until the globulins are coagulated, filter, wash, transfer the filter paper 

 and contents to a Kjeldahl flask, and determine nitrogen as directed above under 

 "Total nitrogen." Multiply the percentage of nitrogen obtained by 6.25 for the 

 percentage of coagulable proteids. 



(e) DETERMINATION OF PROTEOSES, PEPTONES, AND GELATIN. 



(1) First method. 



This is a combination of Bomer's a method with that of Allen and Searle, 1 ' as mod- 

 ified by Wiley. 



Evaporate the filtrate from the globulins to small volume, add 2 or 3 drops of 1-3 

 sulphuric acid, and saturate with powdered zinc sulphate. The excess of zinc sul- 

 phate added should not be large, as otherwise serious "bumping" is likely to ensue. 

 About 80 grams of the salt are required for each 50 cc of liquid. Allow the coagu- 

 lated proteids to subside, filter, and wash with a saturated solution of zinc sulphate. 



Acidulate the nitrate from the zinc sulphate precipitate with 2 or 3 drops of strong 

 hydrochloric acid, dilute with an equal volume of water, add about 2 cc of liquid 

 bromin, and shake the contents of the flask vigorously. (This can be most conven- 

 iently done in a Kjeldahl flask. ) If the bromin be all taken up, add more until 

 about 0.5 cc of liquid bromin is left undissolved and the supernatant liquid thor- 

 oughly saturated. Allow the mixture to stand over night, decant the supernatant 

 liquid through a filter paper, and wash with water, so directing the jet that the glob- 

 ule of bromin is stirred up and saturates the wash water. Return the filter paper 

 and precipitate to the flask, add the zinc sulphate precipitate and filter paper con- 

 taining it, and determine the nitrogen as directed under "Total nitrogen." The per- 

 centage of nitrogen so found, multiplied by 6.25, gives the percentage of proteoses, 

 peptones, and gelatin, including gelatin peptone. 



(2) Second method.' 1 



Heat the filtrate from albumen and globulins, add a slight excess of tannic acid 

 and a few drops of a saturated solution of alum, allow to cool, filter, and wash with 

 cold water. Heat the filtrate from the tannic-add precipitate almost to boiling, add 

 an excess of phospho-tungstic acid, e separate the precipitated proteids by filtration 



Ztschr. anal. Chem., 1895,5,562. 



b.The Analyst, 1897, 22, 258-263. 



U. S. Dept. Agr., Div. of Chem., Bui. 54. 



Mallet, U. S. Dept. of Agr., Div. of Chem., Bui. 54. 



Mallet employs two solutions, one containing 50 and the other 100 grams of crystalline phospho- 

 duodeci-tungstic acid dissolved in 1 liter of 2i per cent of hydrochloric acid. He also recommends the 

 addition of sand or pulverized glass to prevent the foniDition of the coagulated proteids in a deuso 

 clot. Owing to the liability of "bumping" in the presence of such substamvs. however, during the 

 determination of nitrogen it would seem that such addition should be avoided if possible. 



