Effects of Ascorbic Acid on the Formation Process for a Heat-induced Gel of Fish Meat (Kamaboko)

The effects of ascorbic acid (AsA) on the formation process for a heat-induced gel offish meat (kamaboko) were examined. An investigation of the bonds influenced by adding AsA indicates that the aggregation of protein by noncovalent binding decreased and that by cross-linking, except for disulfide bonding, significantly increased in comparison with the control during a 30- min incubation at 40°C (suwari process). The results from the same investigation on a heat-induced gel incubated at 90°C for 30 min without using the suwari process, and the effects of AsA on the activity of transglutaminase indicate that this difference was derived not from activation of the enzyme by AsA but from the direct effect of AsA on the proteins. No effect of AsA on the increase in surface hydrophobicity of crude actomyosin at 40 and 90°C was found. Moreover, when the surimi with modified sulfhydryl groups was used, the disappearance of aggregation influenced by adding AsA and an accumulation of aggregates by noncovalent bonding during the formation of a heat-induced gel occured. These results suggest that polymerization during the formation of a heat-induced gel proceeded as follows: native proteins were first aggregated by noncovalent bonding, next by disulfide bonding, and finally by cross-linking apart from disulfide bonding, and that AsA improved the quality of a heat-induced gel by accelerating the formation of disulfide bonds.