Factors Decreasing the Gel-forming Ability of Threadfin Bream Surimi and Effect of Soybean Whey Addition

Abstract

　Factors that deteriorate the quality of the fish paste products containing threadfin bream and the ability to suppress these effects were investigated. The myosin heavy chain (MHC) in the gel of threadfin bream surimi was degraded by heating from 40 to 60℃. The gel strength of threadfin bream was softer than that of Alaska pollack. The protease activity in threadfin bream surimi was 799 mU/g, which was approximately 6-fold higher the activity of Alaska pollack surimi. One trypsin-like serine type protease and two metalloproteases were detected using threadfin bream surimi. MHC degradation in the gel was suppressed by the addition of protease inhibitor. These results indicate that the decrease in the gel-forming ability in threadfin bream surimi was caused by internal protease that decomposed MHC. The addition of the trypsin inhibitor (TI) and soybean whey containing TI was effective for suppressing these effects.