Studies On Cathepsin Of Silver Carp And Means Of Improving Gel Property Of Surimi

Our country freshwater fish breeding developed very quickly, yet processing fall behind relatively. At present freshwater fish oridinarily saled in fresh , seldom was used to process. Although the silver carp had very good processing and gel property, yet it was limited to use because of its protein tendding to morori. This thesis took the freshwater fish silver carp as the research target, by means of dominating endogenous cathepsin and increasing outward transglutaminase and cryoprotection to improve the gel strength of surimi and restrain the denaturalization.Research made known, endogenous cathepsin in the silver carp muscle took the significant action in surimi morori. Cathepsin L and cathepsin B presented descent tendency after slaughter, cathepsin H attained highness in 30min after slaughter. The optimum temperature of cathepsin L and cathepsin H was 55 ℃,but cathepsin B was 45 ℃. Cathepsin had strong resistant to high temperature, when the temperature overtook 65 ℃, the activation of cathepsin dropped very quickly, up to 85 ℃,it essentially completely losing lives. The optimum pH of cathepsin was 5~7. Washing and chopping with salt could cut down the activation of all 3 kinds of cathepsin. The experiment demonstrated that NaHCO3 solution was more ideal. Increasing non-muscle protein and E64 could reduce the activation of cathepsin.By means of SDS-PAGE electrophoresis, it was known that cathepsin had high activation at 55℃, at this temperature myosin degradation severely.30min after slaughter, myosin nearlly disappeared. By electron microscope, it was known cathepsin had an significant effect on microstructure of fish muscle.Increasing outward transglutaminase had an important effect on improving gel strength of surimi. It was demonstrated that the optimum dosage, optimum reaction temperature, optimum reaction time and reaction pH of transglutaminase was 6%, 40℃, 1.5h, and pH7 differently.Increaseing cryoprotection as oligosaccharides, sorbitol, sucrose, could resist denaturalization of protein in surimi effectively. Mixed phosphate improved the water-holding capability of surimi. Obtained by means of the experiment :the optimum dosage of 4 kingds of cryoprotection was that oligosaccharides was 4%, sorbitol was 2％,sucrose was 1%,mixed phosphate was 0.3% respectively. Postgraduate:Li Yanqing Specialty:Food Sciene Supervisor: Prof.Kong Baohua...