Effects Of Cathepsins On The Quality Of Grass Carp Surimi

Grass Carp, as one of the most production economic kind of freshwater fish, it’sstill mainly marketing fresh in our country. The output value is low, and comparedwith marine fish the meat is less well, it’s difficult to achieve large-scale processing,the significant reason is that Grass Carp contains a lot of endogenous cathepsinwhich results in low fish quality. Grass Carp as the main research object in this paper.The effect of endogenous cathepsin on surimi quality was studied, and reasonableadditive agent as a protease inhibitor was seeked to control the activity of theendogenous cathepsin, the ratio of different additive agents was optimized to enhancethe surimi gel strength and the quality of minced fish was improved, the researchcovered the following four parts:1. Four Chinese fish was used as raw material. Four Chinese fish was washedthree times respectively, the activity of cathepsin B, H, L and several physical andchemical indicators of washed and unwashed Four Chinese fish surimi weremeasured, the quality of Four Chinese fish surimi was contrasted. Result as follows:Four Chinese fish surimi cathepsin H was almost washed off, its retention rate wasextremely low, and the residual rate of cathepsin B and L was high. The gel strengthof Four Chinese Carp were as follows: Black Carp> Silver Carp> Bighead Carp>Grass Carp, the performance of Grass Carp surimi gel strength was weakest.2. In order to improve the quality of Grass Carp surimi, Grass Carp was used asraw material, several saccharide category and protein category additive agents wereadded to the Grass Carp surimi. After additive agents were contrasted, collagenworked on inhibiting cathepsin B and L was better than others, Grass Carp surimi gelperformance was strongest after sucrose+sorbite was added, and the water-holdingperformance of surimi was best after potato starch was added. The results showed thatthe preferably saccharide category additive agents were potato starch and sucrose+sorbitol, and the best protein category additive agent was collagen.3. The SDS-PAGE atlas of Grass Carp surimi autolyzed under different conditions of temperature and pH was analysed, the optimum temperature of GrassCarp surimi autolyzed was at65℃, and the optimum pH value was at6.5. Aftersurimi had been autolyzed different times, SDS-PAGE atlas and gel strength wereanalysed, the ability of potato starch filling in surimi protein crosslinking structurewas better than the collagen, but collagen worked on inhibiting cathepsin was betterthan potato starch. By measured four types of chemical reaction of surimi afteradditive agents were added, The ionic bonding, hydrogen bonding, hydrophobicinteraction and disulfide bond in surimi were changed, thus achieved the goal ofimproving the quality of surimi.4. In order to make full use of the advantages of filtered additive agents, GrassCarp was used as raw material, the ratio of potato starch, sucrose+sorbite andcollagen was designed. The optimized proportion was got, the proportion of collagenwas1%, potato starch was3%, and sucrose+sorbitol was2%. The gel strength andwater-holding performance between optimized additive agent and whey protein hadno significant difference during freezing storage of Grass Carp surimi, but the gelstrength and water-holding performance of two additive agent groups weresignificantly better than the blank control group, they had good effect on keeping thequality of the surimi during freezing storage.