Inhibition of proteases in surimi gels from jack mackerel (Trachurus murphyi)

The effects of 0-5% levels of beef plasma, egg white and potato extract as protease inhibitors of jack mackerel surimi (Trachurus murphyi) and their effects on functional properties were studied. Gel quality was evaluated measuring gel strength, deformation, rupture force, water holding capacity, color and sensory evaluation. Maximum proteolytic activity was round at 65 degrees C after 60 min where the gel quality was markedly deteriorated. At a level of 1% beef plasma, egg white or potato extract, protease inhibition of 91.9%, 82.7% and 74.4%, respectively, was found. Beef plasma at 1% was the most effective protease inhibitor and was the most acceptable for the judges, but produced a gel with a yellow hue. SDS-electrophoresis verified the action of inhibitors in preventing degradation of high molecular weight proteins which form the gel network.