1Kochi Prefectural Industrial Technology Center, Nunoshida, Kochi 781-5105, 2Department of Aquaculture, Faculty of Agriculture, Kochi University, Nankoku, Kochi 783-8502, Japan
The fish (five species of surface fish and five species of bottom fish) caught off Kochi Prefecture were used for preparing the sarcoplasmic proteins. These were fractionated with ammonium sulfate. Inhibiting ability of each fraction to serine protease and cysteine protease was examined. The 50-60% saturated fraction (Sp-60) in all species showed inhibition to serine protease and that in six species to cysteine protease. In order to examine the inhibitory effect of Sp-60 on modori and protein molecular behavior around 40°C, Sp-60 was added to walleye pollack frozen surimi gels. Sp-60 from every fish species except spotted-tail grinner inhibited modori and degradation of myosin heavy chain, though the inhibiting degree varied with species. Sp-60 of bottom fish, especially of redbanded searobin and longwing searobin, was more effective than that of surface fish.