EFFECT OF THERMAL PROCESSING ON MINCED FISH GEL TEXTURE

Abstract

ABSTRACT Effects of rate of heating and final internal temperatures on the texture of fish gels were studied using mechanically deboned fish tissues of 2 species and 2 harvest locations. Generally, rapid heating to 85°C internal temperature (using 100°C steam) produced a firmer, more springy texture in fish gels in comparison with those heated slowly to 70°C internal temperature. However, these thermal effects on gel textures were species and harvest location dependent. Degradations of tropomyosin and myosin observed in cooked fish gels were highly related to gel textural properties. Results further suggested that changes in muscle proteins during heating were caused by proteolytic factor(s) in the sarcoplasmic fraction. The proteolytic crude fraction was isolated and partially characterized. Optimal temperature for proteolytic activity was 60°C; optimal pH was between pH 8.0 and pH 8.5; calcium ion activated the proteolytic activity and the optimal calcium ion concentration for activation was 1 mM; metal chelators, EDTA and EGTA, inhibited the proteolytic activity. A thorough understanding of these proteolytic factors and their subsequent control is important for the utilization of mechanically deboned fish tissues.