Study On The Quality Improvement Technology Of The Peeled Penaeus Vannamei Shrimp During Freezing Preservation

Litopenaeus vannamei is mainly breeding shrimp in our country,the annual output up to 1.5 million tons,about 55%of the total shrimp breeding.In addition to fresh sales,Litopenaeus vannamei mainly by freezing processing to be processed into raw shrimp,peeled shrimp,fried fantail shrimp,shrimp ball products as low temperature circulation.The peeled shrimp is one of the important product.Frozen peeled shrimp will appear frozen juice erosion,lipid oxidation,fleshy become poor.Although traditional composite phosphate can improve the water retention of frozen shrimp,but it can't effectively restrain shrimp from lipid oxidation and deterioration caused by microbial breeding in the frozen processing,in addition,using phosphate excessivly could lead to poor product flavor,produce unpleasant metal astringency,and lead to the deterioration of the product flavor,organizational structure become rough,serious when still harm to human health.In this paper,achieved as the research object,and improving the storage quality of frozen shrimp in two ways,one is soaked the shrimp in the non-phosphorus water retention agent to achieve the purpose of holding water;One is to use the new type of garment of ice on the frozen shrimp glazing processing.The main research contents and also conclusions are as follows:1.Non-phosphorus water retention agent was determined by single factor experiment components and its concentration range.The concentration of sodium chloride is0.1%-0.5%?w/v?,the concentration of trehalose is 0.4%-0.8%?w/v?,the concentration of potassium bicarbonate is 0.1%-0.5%?w/v?,the concentration of agaro-oligo saccharide is0.1%-0.5%?w/v?.Based on the single factor experimental results,using neural network to optimize formula of non-phosphorus water retention agent,the optimal parameter of non-phosphate additive is that the concentration of agaro-oligo saccharide is 0.50%,the concentration of trehalose is 0.62%,the concentration of sodium chloride is 0.30%,the concentration of potassium bicarbonate is 0.17%.2.With shrimp as raw material,using the optimization non-phosphorus compare to traditional phosphate and untreated group,study the quality change of shrimp during freezing storage.Results show that the storage period of 80 days,unprocessed shrimp thawing water loss rate of 11.25%,significantly higher than that without phosphorus aquasorb combined treatment group?7.01%?and phosphate treatment group?7.92%?;Optimization of phosphorus aquasorb group cooking loss rate was significantly lower than without phosphorus aquasorb group;Untreated group shrimp moisture content was reduced by 25.85%,composite phosphate treatment group decreased by 22.48%,optimization of phosphorus aquasorb group decreased by 17.49%,no phosphorus aquasorb group effectively keep the moisture of frozen shrimps;Phosphorus compound phosphate treatment group and the optimization of super absorbent polymers treatment group of shrimp Ca²⁺-ATPase activity change is relatively close,to store the 80 th day,the active in0.325?mol Pi/mgprot/hour,significantly higher than that of untreated group activity.The above experimental results show that the optimized without phosphorus water retention agent can significantly increase,marina prawn frozen shrimp water retention,and can slow down the frozen shrimp quality deterioration during storage,can replace traditional phosphorous water retention agent.3.Chitosan?CS?and poly-?-glutamic acid??-PGA?as materials,ice clothing liquid was prepared using ionic-gelation method.The particle size of the prepared nanoparticles were examined by nano particle size analyzer;The size and morphology of particles were examined by transmission electron microsope?TEM?;The structure of particles was analyzed by infrared spectroscopy?FTIR?and compared it with the internal structure of chitosan,poly glutamic acid;The results showed that particle size distribution in around300nm?hydrate particle size?,the mean particle size of the dispersion system were100-200 nm under the TEM,and the morphology was spherical in shape.it was the nanometer particle system prepared by chitosan and poly glutamic acid with the concentration ratio of 1:1 that had the highest viscosity.It was found that the dispersion system had a good stability when concentration of chitosan and poly glutamic acid were0.15%?w/v?,and its best storage temperature is 4?,the optimal pH value of 6.3.4.Use of the new ice clothing liquid,namely chitosan/gamma-poly glutamic acid emulsion on frozen shrimp glazing process,studies its weight loss in the process of storage,pH value,TBARS,TVB-N value changes.Different liquid ice garment processing of ice frozen shrimps yield was no significant difference.After 90 days storage,different concentration of chitosan/gamma-poly glutamic acid emulsion treatment group,there was no significant difference respectively by 0.84g/100 g growth to and from 0.88g/100 g to1.64g/100 g and 1.68g/100 g.During the period frozen shrimp of pH value between6.85-7.18,suggesting that stored frozen shrimp meat pH change was not significant,but the chitosan/gamma-poly glutamic acid emulsion glazing shrimp pH always significantly lower than the control group,description of emulsion may be more effectively inhibit the growth of bacteria,thereby reducing the speed of the decomposition of protein.Storage at the end of the emulsion glazing treatment group of TBARS value of 0.14 mg/100 g,and chitosan/gamma-poly glutamic acid emulsion glazing of shrimp TVB-N value is only15.27 mg/100 g,is far lower than the other treatment groups,indicating that chitosan nano emulsion glazing process can effectively inhibit lipid oxidation in shrimp frozen storage,and can effectively control the growth of the value of TVB-N.