Suwari gel properties as affected by transglutaminase activator and inhibitors

Effect of transglutaminase activator and inhibitors on textural properties and cross-linking of myofibrillar proteins in suwari gel of surimi from four fish species, including bigeye snapper, threadfin bream, barracuda and bigeye croaker was investigated. Breaking force and deformation of suwari increased as calcium chloride added increased (P<0.05); however, a slight decrease was observed with an excessive amount of addded calcium chloride. With addition of calcium chloride, the concomitant decrease in solubility of suwari gel, in a mixture of sodium dodecyl sulfate, urea and β-mercaptoethanol, suggested increased non-disulfide covalent bond formation. Conversely, the addition of transglutaminase inhibitors, including N-methylmaleimide (NEM), ammonium chloride and EDTA, resulted in a marked decrease in breaking force and deformation, especially with increasing concentration. The decrease in gel-forming ability was associated with the decrease in non-disulfide covalent cross-linking, as indicate by an increase in solubility and more myosin heavy chain (MHC) retained. The results indicate that endogenous transglutaminase played an essential role in setting, at high temperature (40 °C), of surimi from tropical fish.