MEAT AND <\i KAT PK< >1>1 H'TS. 



1 i: 



Preservatives," page 17!). In p-neral, preservatives may be separated from 

 meat by digesting a lV\v minutes in warm water made slightly acid or slightly 

 alkaline, according as the nature of the preservative is basic or acid. 



(a) SULPHUROUS ACID. 



The distillation method for the detection of sulphurous acid (see page 187, 

 d-M- "XXVII. Food Preservatives") may bo employed for the examination 

 of meat, using 20 cc instead of 5 cc of the 20 per cent solution of phosphoric 

 acid. Mere traces should be ignored. According to Ostertago the microscopic 

 examination of meat that has been preserved with sodium or calcium sulphite 

 often discloses the presence of crystals of sodium or calcium sulphate, due to 

 partial oxidation of the sulphite. 



In the absence of chlorids and nitrates, Kammerer a employs potassium iodate 

 paper in the following manner: Place the sample of meat on potassium iodate 

 paper and moisten it with dilute sulphuric acid (1:8) free from oxids of nitro- 

 gen. In the presence of even minute traces of sulphites a deep blue color is 

 immediately formed, while in the absence of sulphites only a faint blue color is 

 produced, and that after a considerable time. This method is of limited applica- 

 tion, since it can not be used with meats containing salt or saltpeter. 



13. Detection of Coloring- Matter. Provisional. 



Sausages and other preparations in which chopped meat is employed rapidly 

 became discolored on exposure to the air. This change does not take place to a 

 marked extent with meat that has been cured in a pickle containing saltpeter. 

 With fresh chopped meat, and sometimes with corned meat, especially that cured 

 without saltpeter, coloring matter is sometimes added to prevent the change of 

 color which would naturally take place. The coloring matter may often be 

 extracted by heating for fifteen or twenty minutes with 50 per cent alcohol, with 

 50 per cent glycerin slightly acidified, with a mixture of alcohol and glycerin,* 

 with ammonium hydroxid, or with a 5 per cent solution of sodium salicylate c in 

 water. Approximately equal weights of meat and solvent may be used. 



In case the filtered extract by any of these methods is colored red or deep 

 yellow, evaporate it nearly to dryness, slightly acidify with hydrochloric acid, 

 and boil a few minutes after the addition of a thread of fat-free wool. If the 

 wool is dyed, examine it as directed under "XXVIII. Coloring Matter," page 

 190. If the wool is not dyed, examine the solution spectroscopically. 



If too dilute, the solution may often be concentrated by precipitating the color- 

 ing matter as a lake,<* that is, allow it to settle, decant the water, dissolve in 

 hydrochloric acid, and make alkaline with ammonium hydroxid. 



In extracting with 50 per cent alcohol, the proteids of the meat are coagulated, 

 with the formation of a pale, almost white, color. If the meat is not discolored 

 during this extraction, it is probable that some foreign color is present. 



Marpmann e examines sausages microscopically for the presence of coloring 

 matter after dehydrating with alcohol and xylol consecutively, removing the 

 xylol with carbon tetrachlorid, and immersing in cedar oil until the natural 

 .colors of the meat have disappeared. 



Handbuch der Floischbeschau, 3d ed., p. 82C. 

 "Klinger and Bujard, Zts. angew. Them., 1891, 515. 

 c Spaeth, Pharm. Centralh., 1897, 38: 884. 

 A Bremer, Forschungs-Ber. Lebensm., 1897, 4: 4f>. 

 'Zts. angew. Mikros., 1895, 1: 12. 



