Effect of some protein additives on proteolysis and gel-forming ability of lizardfish ( Saurida tumbil)

Abstract

Effect of beef plasma protein (BPP) and egg white (EW) on proteolysis and gelling properties of lizardfish ( Saurida tumbil) was investigated. Both BPP and EW showed the inhibitory activity toward heat-activated sarcoplasmic proteinases and autolysis of lizardfish mince and washed mince at 60 °C in a concentration-dependent manner. BPP was more effective in proteolysis prevention than EW as shown by more retained myosin heavy chain (MHC) on SDS–PAGE. Effect of BPP and EW (1, 2 and 3%) on the properties of lizardfish surimi prepared under different heating conditions (40/90 °C, 60/90 °C and 90 °C) was also studied. Regardless of heating conditions, incorporation of BPP and EW resulted in the increased breaking force and deformation of surimi gels. Nevertheless, BPP showed higher gel strengthening effect than EW. Addition of BPP resulted in a lower whiteness, while no changes in whiteness were observed with gels added with EW. Therefore, proteolysis of lizardfish muscle or surimi, associated with endogenous proteinase, can be retarded by the addition of BPP or EW, leading to the increased gel strength.