The Study On The High Quality Tilapia Surimi

The chemical composition of tilapia and its surimi and the characteristics of surimi protein in the tissue, the optimal conditions of deodorization and the effect of enzymatic hydrolysates of cod fish skin on surimi frostresistance were researched. Research covered the following four parts:1. The chemical composition of tilapia meat and its surimi was determined in this article. The results showed that the protein content of tilapia fish is 15.28%, fat content is 2.25%, so it is a high protein, low fat fish. Myofibrillar protein with the highest content is the main protein of surimi. The characteristics of cathepsin in surimi protein were also researched. The results showed that residual activity of cathepsin L after rinsing was up to 80.96%, leading to the main gel degradation enzymes of tilapia surimi, while the residual activity of cathepsins B, H was 11.49% and 3.53% after rinsing, respectively.2. Take trimethylamine, sensory evaluation and gel strength as index,we studied the process of deodorization and the effect of deodorization on surimi quality, and determined the best conditions of deodorization by single factor and orthogonal experiment, and studied the whiteness, gel strength, cathepsin activity, myofibrillar protein ATPase activity and solubility of surimi The best conditions of deodorization and bleaching were: the inoculum of 1.5% yeast, 35℃, pH 6.5, fermentation for 40min . Washing with water two times, 0.25% salt water 1 times, washing time is 3min each. washing can not only alleviate the bad smell taste but also raise the gel strength of surimi. Odor removal little effect on enzyme activity, washing can go out almost all of cathepsin H, part of cathepsin B and a small amount of cathepsin L.3. The effect of different pretreatment on frozen surimi was studied. The surimi was treated under 50℃water bath for 30s, 60s, 90s; 60℃water bath for 30s, 60s; microwave with 137w for 30s, 60s. The effects of different pretreatments on the content of non-frozen water, protein denaturation temperature, rheology, protein interaction, salt solublity, myofibrillar ATPase activity of protein solution, gel and water holding capacity were researched comprehensively,and the results showed that the surimi treated by microwave for 60s was the best.4. The effect of addition of two hydrolysates on anti-freezing propertyof surimi were studied, water holding capacity, whiteness, and its non-freezing water content, salt soluble and myofibrillar ATPase activity of protein solution. acted as indicators, Commercial antifreeze agent used as control experiment. The result showed that effect of adding 5% protease enzyme hydrolysate was the best.