Oxymyoglobin in bovine muscle systems as affected by oxidizing lipids, vitamin E and metmyoglobin reductase activity

Oxymyoglobin and lipid oxidation were examined in low and high vitamin E (a lpha -tocopherol) bovine M. longissimus thoracis et lumborum (LD) homogenat es and in subcellular fraction of LD. Investigation of the effects of tempe rature (4, 22, 37C) and pH (5.5, 6.4, 7.2) on lipid and oxymyoglobin oxidat ion indicated that oxymyoglobin oxidation increased with increasing tempera ture (P less than or equal to 0.05) and was higher at the low pH (P less th an or equal to 0.05). Lipid oxidation increased with temperature (P less th an or equal to 0.05) only at pH 5.5. The inclusion of 45 muM FeCl3/ascorbat e (1:1), at pH 5.5 and 4C, led to significant increases (P less than or equ al to 0.05) in lipid oxidation bur significant oxymyoglobin oxidation occur red only when the extent of lipid oxidation exceeded a threshold level. Oxy myoglobin and lipid oxidation were significantly lower in LD fractions deri ved from high vitamin E muscle compared to low vitamin E muscle. alpha -Toc opherol did not interact directly with oxymyoglobin to suppress oxymyoglobi n oxidation but a positive unit effect of muscle alpha -tocopherol on metmy oglobin reductase activity was observed.