CATALYSTS OF LIPID PEROXIDATION IN MEATS. 1. Linoleate Peroxidation Catalyzed by MetMb or Fe(II)‐EDTA

SUMMARY The possibility of catalysis of unsaturated fat oxidation by both hemoprotein and non‐heme iron components of meat has been pointed out. Model systems of these 2 catalysts have been compared. The hemoprotein MetMb accelerated linoleic acid peroxidation in pH range 5.6–7.8, the catalysis increasing with pH. A complex of ferrous ion and ethylenediaminetetraacetic acid [Fe(II)‐EDTA]–a non‐heme iron model–in a 1 to 1 ratio accelerated peroxidation at lower pH; no catalysis took place above pH 6.4. Most chelating agents eliminated Fe(II)‐EDTA catalysis, but had no effect on MetMb catalysis. Reducing agents, both ascorbic acid and thiols, on the other hand, accelerated Fe(II)‐EDTA catalysis but inhibited MetMb catalysis. Other sulfur compounds with ‐S‐ or ‐S‐S‐ groups, except thiodipropionic acid (TDPA) at concentration of 6 × 10 ‐3 M, showed no effect on either type of catalysis.