MEAT AND MEAT PRODUCTS. 



109 



to boiling, add an excess of phosphotungstic acid,<* separate the precipitated 

 proteids by nitration and wash with hot water, being careful that the tempera- 

 ture of the solution and wash water shall no* be less than 90 C. at any time. 

 Transfer the filter papers containing the tannic acid and phosphotungstlc 

 acid precipitates to a Kjeldahl flask and determine nitrogen. The nitrogen so 

 obtained multiplied by C.25 gives the percentage of proteoses, peptones, and 

 gelatin. 



(f) MEAT BASES. 



Deduct from the total nitrogen the sum of the nitrogen obtained in the deter- 

 mination of insoluble proteids, coagulable proteids, proteoses, peptones, and 

 gelatin for the nitrogen of the meat bases. Multiply the result by 3.12 to 

 obtain the percentage of meat bases. 



8. Starch. 



(In chopped meat, sausage, deviled meat, etc.) 

 (a) QUALITATIVE DETERMINATION. PROVISIONAL. 



Treat 5 or 6 grams of the sample with boiling water for two or three minutes ; 

 cool the mixture, and test the supernatant liquid with iodin solution. In using 

 this test it must be remembered that a small amount of starch may be present 

 as the result of the use of spices. If a marked reaction is given, however, it 

 may be concluded that starch or flour has been added, and a quantitative deter- 

 mination may be made. The above qualitative method may be replaced by a 

 microscopic examination, by which not only the presence of added starch, but 

 also the variety employed may be determined.. 



(b) QUANTITATIVE DETERMINATION. 

 (1) AMBUHL'S METHOD. & PROVISIONAL. 



This method is short and convenient, but the results obtained by it are only 

 roughly approximate. 



Thoroughly macerate 2 grams c of the meat under examination with 50 

 times its weight of water. Boil for thirty minutes and dilute to 300 cc for every 

 grain of meat employed. Cool an aliquot of the liquid, treat with iodin, and 

 compare the depth of color with solutions containing a known amount of the 

 same kind of starch (the variety of starch in the sample is determined micro- 

 scopically), and boiled for the same length of time. 



(2) MAYRHOFER'S METHOD <* MODIFIED. PROVISIONAL. 



Treat from 10 to 20 grams of tlTe sample under examination (depending upon 

 tho amount of starch indicated by the iodin reaction) in a porcelain dish or 



'allet employs two solutions, one containing 50 and the other 100 grams of crystal- 

 lino phosphoduodecitungstic acid dissolved in 1 liter of 2.5 per cent hydrochloric acid. 

 He also recommends the addition of saud or pulverized glass to prevent the formation of 

 coagulated proteids in a dense clot. Owing to the liability of " bumping " in the presence 

 of such substances, however, during the determination of nitrogen it would seem that such 

 addition should be avoided if possible. 



6 Pharm. Centralh., 1881, 22: 438; Abstract Zts. anal. Chem., 1882, 21: 436. 



r Ambiihl directs that from 2 to 10 grams be employed, according to the size of the 

 meat particles. If the sample be macerated, however, as directed under the preparation 

 of sample, it is unnecessary to employ a large amount. 



d Forschungs-Ber. Lebensm., 1896, 3: 141; Ibid., 1897, 4: 47. 



