Participation of the Superoxide Radical in the Beneficial Effect of Ascorbic Acid on Heat-induced Fish Meat Gel (Kamaboko)

Abstract

The influence of ascorbic acid (AsA) on the proteins in raw meat paste (surimi) of walleye pollack during the formation of a gel by incubating at 40°C, or 40°C and 90°C was examined by SDS-polyacrylamide gel electrophoresis. AsA significantly enhanced the decrease in the amount of myosin heavy chain (MHC), by promoting the polymerization of MHC via disulfide bridging. Diethylenetriaminepentaacetic acid, a chelator, and tiron, a scavenger of the superoxide radical, both inhibited the promoting effect of AsA on MHC polymerization in surimi. Therefore, the superoxide radical generated via the metal-catalyzed autoxidation of AsA participated in the polymerization of MHC. The production of the cysteine (Cys) thiyl radical due to superoxide in a 10 mM Cys solution was confirmed by electron spin resonance spectroscopy, in which superoxide was generated by photo-activation of riboflavin. These results suggest that the polymerization of MHC by AsA proceeds through a radical-radical reaction of the thiyl radicals of Cys residues that are generated by superoxide radicals.