Study On Processing Technology Of Ready-to-eat Silver Carp Surimi Product Stored At Ambient Temperature

Surimi products have many advantages,such as high protein,low fat and so on,and they now have become one of the most popular food among consumers.Therefore,ready-to-eat leisure food made from surimi can greatly improve the convenience.At present,there have been similar commercial products in the market with high-temperature sterilization which could inevitably damage the texture quality of the products,therefore,it is urgent to improve the processing technology of the products.This study focus on improvement of the quality of surimi.On the one hand,glucose acid lactone(GDL)was added to make surimi become acidified food(pH<4.6)and reduce the sterilization intensity.On the other hand,acid-resistant exogenous additives were added to further improve the strength of surimi gel and lower the expressible water content.Eventually,one ready-to-eat surimi leisure food was developed with long shelf life and better convenience as well as high nutrition,flavor,taste,and so on.1.The effect of GDL on the gel properties of surimi gel was studied.Firstly,according to the principle that the pH of acidified food must be lower than 4.6,it was determined that the addition amount of GDL was 2.0%(With a total mass of surimi gel as a baseline measurement).Secondly,the effect of setting temperature and time on the physicochemical properties of GDLinduced surimi gel were studied.The results showed that the acidification rate increased with the temperature increasing from 30°C to 50°C.Consequently,the time for the gel pH to stabilize was shortened.The gel strength,hardness,springiness of GDL-induced surimi gel declined,the expressible water content increased and not much differences in whiteness was observed.With reference to sensory evaluation,the optimal setting conditions was as follows: setting temperature was 35°C,setting time was 3.0 h.Through analyzing the mechanism of the gel,it was found that the water-soluble protein and the salt-soluble protein gradually changed into insoluble protein during gel formation.The trend of insoluble protein was the same with gel strength,which indicated that the insoluble protein was the basis of the formation of highstrength gel.The surimi gel mainly formed through hydrophobic interaction,disulfide bond,disulphide bond and all of them decreased with increasing of temperature,consistent with the trend of gel strength.The result of SDS-PAGE showed that myosin heavy chain contributed the most to the formation of surimi gel,but it was less affected by temperature.The result of SEM revealed a compact and fine microstructure with the condition of 30°C,3.5 h.2.The effect of soybean protein isolated(SPI),hydroxypropyl potato distarch phosphate(HPDP),locust bean gum(LBG)on properties of GDL-induced surimi gel were studied.The results indicated that three additives all have certain positive effect on the properties of the surimi gel.The optimum formulation was determined by orthogonal test,taking into account the gel strength,water holding capacity and sensory index.The optimum formulation was as follows: SPI 2%,HPDP 3% and LBG 1%(With a total mass of surimi gel as a baseline measurement).3.The optimization of sterilization technology was studied.The relationship between Fvalue and sterilization time(under different sterilization temperature)was determined according to the measurement the center temperature of the product.The safe F-value was determined to 6.5 min by combining with commercial sterility test.Finally,the effect of the different sterilization conditions(90°C,31.4 min.95°C,17.2 min and 100°C,10.8 min)with the same F-value(6.5min)on the quality of surimi gel were studied.The results showed that the gel strength,hardness and springiness of the product were relatively higher under the sterilization condition with high temperature and short time,the expressible water content was relatively lower and the whiteness not had much differences.The optimal sterilization condition was determined with the sensory evaluation: sterilization temperature was 100°C,sterilization time was 10.8 min.Through analyzing the mechanism of the gel found that the hydrophobic interaction,disulfide bond and disulphide bond content were all higher under the sterilization condition with high temperature and short time,this was also the reason why the gel strength was relatively higher;the higher TCA-peptide content indicated that the sterilization condition with high temperature and short time could reduce the degradation of protein.But the temperature had less impact on the MHC band intensity and insoluble protein content.4.The shelf life of product was predicted.Hardness and whiteness were verified to be the main factors that affect the quality of product by the correlation analysis between the pH,TVBN,gel strength,hardness,springiness,whiteness and sensory evaluation during the preservation.Through the first-order reaction kinetic model and Arrhenius equation,the shelf life of product were 241 and 213 days respectively under 25°C by the determination of hardness and whiteness.Considering the errors of raw material production and operation,the shelf life at ambient temperature was suggested as 180 days.