Autolysis and Characterization of Sarcoplasmic and Myofibril Associated Proteinases of Oxeye Scad (Selar boops) Muscle

Abstract

ABSTRACTThe autolytic profile of oxeye scad mince was characterized. Mince showed higher proteolytic activity than washed mince. The highest autolysis was observed at 65 and 60°C for mince and washed mince, respectively. Both mince and washed mince showed the optimum pH for autolysis at pH 9.0, and their activities decreased with increasing NaCl concentration (0–3.5%). Autolysis of washed mince was markedly inhibited by soybean trypsin inhibitor (SBTI), suggesting that myofibril-associated proteinase was serine proteinase. Sarcoplasmic proteinase was characterized to be heat-activated alkaline proteinase having the optimal pH and temperature of 9.0 and 60°C, respectively. The activities were stable at pH range of 8.0–11.0 at 20–40°C. The crude proteinase was inhibited by N-p-tosyl-L-lysine chloromethyl ketone, SBTI, and phenylmethanesulfonyl fluoride, suggesting the predominance of serine proteinases, especially trypsin. NaCl suppressed the activity while β-mercaptoethanol, dithiothreitol, and CaCl2 activated the activity. Therefore, trypsin-like proteinase is a major endogenous proteinase responsible for autolysis in oxeye scad muscle. The present results can be used as scientific guidelines to predict the gel strength of surimi made from oxeye scad muscle.