Fish protein hydrolysate (FPH) was prepared from fish scrap of five marine species by enzymatic treatment for the effective utilization of fish wastes. The major components of the FPH were peptide (82.3-85.8%) with other nitrogenous compounds (11.5-16.3%). Lizard fish Saurida wanieso surimi containing FPH (5.0%, dried weight/wet weight) was stored at -25∞C and the suppressive effects of FPH on the decrease in the gel-forming ability, unfrozen water content and CaATPase activity were determined during the frozen storage. FPH maintained a high gel-forming ability and Ca-ATPase activity were determined during the frozen storage. FPH also suppressed the decrease of unfrozen water content of surimi. These results suggest that FPH can be used as a cryoprotectant to suppress the denaturation of muscle protein of lizard fish surimi during frozen storage.KEY WORDS: Ca-ATPase activity, fish protein hydrolysate, frozen surimi, gel-forming ability, lizard fish, storage period, unfrozen water.

In order to utilize low-cost squid effectively as a functional material for food processing and preservation, squid protein hydrolysate (SPH) was prepared from 4 species of squid by protease treatment. Peptides are the major components (84-88%) of SPH. The protective effect of 5% SPH (dry weight/wet weight) on the freeze-induced denaturation of lizardfish Saurida wanieso myofibrillar protein (Mf) was evaluated on the basis of Mf Ca-ATPase activity and the amount of unfrozen water in Mf, which was determined by differential scanning calorimetry (DSC); the effect was compared with that of sodium glutamate. Mf with SPH showed markedly higher Ca-ATPase activity than did Mf without SPH (control) during frozen storage. Mf with SPH had a higher amount of unfrozen water than the control. These findings suggest that SPH stabilized water molecules in the hydration sphere of Mf and thus, suppressed freezeinduced denaturation of Mf. The effect by SPH was less than that by sodium glutamate.