Abstract: This investigation aimed to study the synergistic effect of a mixed meat tenderizer of calcium chloride, fig protease and kiwifruit protease on the structure of myofibrillar protein in rabbit hind leg meat. We measured and compared the myofibrillar fragmentation index (MFI), myofibrillar protein solubility, soluble protein content (SPC) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) profiles of myofibrillar protein in meat samples treated with each meat tenderizer alone and their combination. The results showed that the mixed tenderizer could degrade myofibrillar protein more effectively than the single tenderizers (P < 0.05). The surface hydrophobicity of myofibrillar protein in the calcium chloride group was significantly higher than that in other single treatments (P < 0.05). The solubility of myofibrillar protein and SPC in the single enzyme treatments were significantly higher than those in the calcium chloride group (P < 0.05). The SDS-PAGE showed that the myosin light chain and C-protein were mainly degraded by fig protease while the myosin heavy chain was mainly degraded by kiwifruit protease. The above results indicate that combined treatment with the meat tenderizers could synergistically enhance the degradation of myofibrillar protein, possibly due to the fact that calcium chloride could make myofibrillar protein unstable, resulting in its unfolding and exposure of more enzyme binding sites, and that the two proteases showed different specific substrate binding patterns prompting protein degradation and solubilization.

Key words: mixed tenderizer; calcium chloride; fig protease; kiwifruit protease; myofibrillar protein; synergistic effect