KINETICS OF PIGMENT OXIDATION IN BEEF FROM STEERS SUPPLEMENTED WITH VITAMIN-E

A model was developed for the mechanistic analysis of pigment oxidatio n on longissimus lumborum (LL) or gluteus medius (GM) from control and vitamin E supplemented cattle. Metmyoglobin (MetMb) formation present ed an induction period which generally increased with supplementation dose and duration, followed by a phase where MetMb accumulated faster than during the induction period. alpha-Tocopherol concentration only affected length of the induction period. Color stable LL had a longer induction period than color labile GM. The model included oxymyoglobin autoxidation to MetMb and superoxide anion, and oxidation of oxymyogl obin to MetMb by prooxidants arising from the superoxide anion. alpha- Tocopherol inhibition was interpreted as a competitive reaction betwee n the antioxidant and oxymyoglobin for lipid peroxy radicals.