SUMMARY—Results in model Mb solutions were confirmed by tests on pork samples treated with the mentioned additives and heated. The content of nitric oxide chromogen (DNOMb) in the samples was determined according to Hornsey. It was found that optimum DNOMb formation required not less than 5 mols nitrite per mol Mb; this may be due partly to side reactions with cysteine and other components of meat. In the presence of sufficient sodium ascorbate (200 mols per mot Mb), 3 mols nitrite per mol Mb was optimum. A large excess of nitrite (500 mols per mol Mb) induced the formation of green pigments, and appreciably less DNOMb was found.Reheating meat containing denatured Mb with nitrite converted Mb to a red pigment, but the color intensity so obtained was 40–60 of that obtained with normal nitrite treatment before heating.Potassium nitrate did not influence the DNOMb formation. The higher the temperature to which meat is heated, the lower its DNOMb content.Exclusion of oxygen by means of carbon dioxide during the treatment of meat improved the final DNOMb content.Irradiation by light of meat containing DNOMb showed that the concentration of nitrite necessary for optimal DNOMb formation in the absence of ascorbate (5 mols nitrite to 1 mol Mb) also caused optimum stability to irradiation in air.Potassium nitrate did not affect this stability. The breakdown of DNOMb increased with the light intensity. In a carbon dioxide atmosphere the breakdown of DNOMb is much slower than in air and it is independent of the light intens
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