COLORING MATTER OF RAW AND COOKED 

 SALTED MEATS 



By Ralph Hoagland, 

 Laboratory Inspector, Biocketnic Division, Bureati of Animal Industry 



INTRODUCTION 



The red color of fresh lean meat, such as beef, pork, and mutton, is 

 due to the presence of oxyhemoglobin, a part of which is one of the con- 

 stituents of the blood remaining in the tissues, while the remainder is a 

 normal constituent of the muscles. When fresh meat is cooked or is 

 cured by sodium chlorid, the red color changes to brown, owing to the 

 breaking down of the oxyhemoglobin into the two constituents, hematin, 

 the coloring group, and the proteid, globin. 



On the other hand, when fresh meat is cured by means of a mixture 

 of sodium chlorid and a small proportion of potassium nitrate, or salt- 

 peter, either as a dry mixture or in the form of a pickle, the red color of 

 the fresh meat is not destroyed during the curing process, the finished 

 product having practically the same color as the fresh meat. • Neither 

 is the red color destroyed on cooking, but rather is intensified. 



The practical value of saltpeter in the curing of meats is so well known 

 that its use for this purpose may be said to have become practically uni- 

 versal ; such use is not confined to the commercial meat-packing industry, 

 but it is used in the home curing of meats as well. 



It is only within comparatively recent j'ears, however, that anything 

 very definite has been known concerning the nature of the color of salted 

 meats or the process of the color formation. The work which is reported 

 in this paper was undertaken for the purpose of obtaining more complete 

 information concerning the color of raw and cooked salted meats. 



HISTORICAL SUMMARY 



Weller and Riegel (1897),' in the examination of a number of samples 

 of American sausages, obtained a red coloring matter on extracting the 

 samples with alcohol and other solvents, which color they concluded to 

 be in some manner due to the action of the salts used in curing upon the 

 natural color of the meat. On account of similaritj' of spectra, this 

 color was considered to be methemoglobin. 



Lehmann (1899) observed that when fresh meat was boiled in water 

 containing nitrites and free acid or in old meat broth the surface of the 

 meat turned bright red in color, in contrast to the brown color which 

 fresh meat takes on when boiled in water free from nitrites. The addi- 



^ Bibliographic citations in parentheses refer to "Literature cited." p. 225- 



Journal of Agricultural Research, Vol. Ill, No. 3 



Dept. of Agriculture, Washiitfiton, D. C. Dec. 15. 1914 



(21 1 ) A— 10 



