INTERACTION OF SUCROSE AND ZINC FOR CRYOPROTECTION OF SURIMI

Stabilization of fish myofibrillar proteins by low molecular weight ca rbohydrates and polyols during frozen storage forms the basis of the s urimi process. Studies have shown that certain divalent cations, notab ly zinc, may enhance the effectiveness of cryoprotective solutes for s tabilizing labile enzymes. This study investigated the interaction of sucrose and zinc for cryoprotection of fish actomyosin(AM). Initial fr eeze-thaw studies, using a model actomyosin system, showed addition of ZnSO4 generally destabilized AM with a loss of Ca(2+)ATPase activity. This was confirmed by making surimi and comparing denaturation (Ca(2)ATPase, salt-soluble protein) and loss of gel-forming ability before and after freeze-thaw treatment. In addition, the surimi studies demon strated the dual effect of sucrose, that of stabilizing the AM protein s while depressing the gelation properties of the surimi. Prior to fre ezing, ZnSO4 reversed the effects of sucrose somewhat and improved gel ation properties when high levels of sucrose were present.