Interaction of Sucrose and Zinc for Cryoprotection of Surimi

Stabilization of fish myofibrillar proteins by low molecular weight carbohydrates and polyols during frozen storage forms the basis of the surimi process. Studies have shown that certain divalent cations, notably zinc, may enhance the effectiveness of cryoprotective solutes for stabilizing labile enzymes. This study investigated the interaction of sucrose and zinc for cryoprotection of fish actomyosin (AM). Initial freeze−thaw studies, using a model actomyosin system, showed addition of ZnSO 4 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 demonstrated the dual effect of sucrose, that of stabilizing the AM proteins while depressing the gelation properties of the surimi. Prior to freezing, ZnSO 4 reversed the effects of sucrose somewhat and improved gelation properties when high levels of sucrose were present.