The Effect of Heating Temperature on the Prooxidant and Hydroperoxide Decomposition Activity of Myoglobin

Abstract

Solutions of myoglobin from the heart of a horse were heated at various temperatures to assess the effect of heating temperature on the prooxidant and hydroperoxide decomposition activity of myoglobin. The solutions of the heated myoglobin were incubated with linoleic acid in various systems and the prooxidant activity was evaluated by measuring the absorbance at 234 nm and thiobarbituric acid (TBA) value. H₂O₂ was added to the reaction mixture to activate the myoglobin. To observe the lipid hydroperoxide decomposition activity of the heated myoglobin, the heat-denatured myoglobin was incubated with oxidized linoleic acid and the residual hydroperoxides were assessed fluorometrically. Both the absorbance at 234 nm and TBA values gave similar results and the incubation of heated myoglobin with linoleic acid resulted in a rather weak prooxidant activity regardless of the heating temperature. The supplementation of H₂O₂ activated myoglobin, whose activity was greatest when heated at 74°C, decreased when heated at 100°C. As a model of pre-cooked frozen foods, a part of the heated myoglobin solution was frozen and reheated. The prooxidant activity of the reheated myoglobin was similar and greatest by heating at 74°C, but when heated at 100°C it was less prominent than that of the control (unheated). The lipid hydroperoxide-decomposition activity of the heat-denatured myoglobin (heated or reheated under the same conditions) showed a slight alteration up to 74°C, however, heating at 100°C significantly lowered this activity.