Effects Of Extract FromR.Philippinarumon Shrimp(Penaeus Vannamei)Melanosis Inhibitionduring Cold Storage

During the process of clam(R.philippinarum), a lot of liquor hasproducedand has been discarded, this results in a waste of resources and environment pollution. In the process of storage, the melanosis caused by polyphenol oxidase(PPO) affected the quality of shrimp. In this study, clam was chosen as the raw material, the clamextractions were extracted by four methods(ammonium sulfate precipitation, hydrolysis-ammonium sulfate precipitation, dialysis, hydrolysis-dialysis method), and their inhibition to mushroom tyrosinase was analyzed. Threemethods were used toget the water extraction liquor, cooked liquor and cooked liquor concentratefrom clam, and the inhibition effect of these extractionsonpolyphenol oxidase of shrimp(Litopenaeus vannamei) and the preservation effect on shrimp were studied. The results were as follows:1. By comparing the inhibition effectsto mushroom tyrosinase with four differentextractions ofthe clam,the hydrolysis-ammonium sulfate precipitation had the best inhibition effect to mushroom tyrosinase, its’ inhibition of PPO activity was 43%. Compared the inhibiton of the extractions with the ammonium sulfate precipitation and the dialysis method, the enzymolysised material were better thanthe raw material.The hydrolysis-ammonium sulfate precipitation optimum conditions were 2000U/g enzyme concentration, 2h enzymatic time, 80%ammonium sulfate concentration, 95%ethanol concentrationwhich used to extractthe clam contents, which were confirmed by the orthogonal test,under these conditions, the mushroom tyrosinase inhibtion was 54.55%.2. By comparing the inhibition that the extractions(water extraction liquor, cooked liquor and cooked liquor concentrate) effected on the shrimp’s PPO,IC50was8.60mg/mLby the water extraction, IC50 was 10.37mg/mLby the the cooked liquor and IC50 was 13.94mg/ml by the cooked liquor concentration, so the water extraction was the best. By comparingtheclam extractions(water extraction liquor, cooked liquor and cooked liquor concentrate)with diffrerent concentration effected on theexternal bacteriostasis of the pseudomonas fragi,the pseudomonas fluorescensand the brochothrix thermosphacta(Takifugy rubripes dominant spoilage organisms),these germ bacterias were beinhibition by three all extractions, andthe water extraction effectedfirm performanceonthe brochothrix thermosphacta and the pseudomonas fragi.3. The shrimphad been preservated with theclamextractions(water extraction liquor, cooked liquor and cooked liquor concentrate) at 4 °C, and analyzed its’ the pH, PPOenzyme activity, total volatile basic nitrogen(TVB-N). The PPO enzyme activity was inhibited by all three extractions from theR.philippinarum, and it was the highest after 1 day.At that moment the PPO activity inhibition by water extraction was 32.35%, and bycooked liquorwas 11.21%, cooked liquor concentration was 6.25%. The TVB-N was reduced by theseall extractions. The total bacterial count was effectively inhibited by the water extraction and cooked liquor. The sensory evaluation results show that the water extraction liquorwas betterthan the others during preservation, after 3 day, the comprehensive score of water extraction liquor, cooked liquor and cooked liquor concentrate was 19, 17 and 14. Therefore, water extraction liquorwas better than the others on the preservation of shrimp.The hydrolysis-ammonium sulfate precipitation’s inhibition of PPO activity was 54.55%.The inhibiton that water extraction liquoreffected on shrimp’s PPO was better than the others, and IC50 was 8.60 mg/mL.The shrimphad been preservated with the clamextractions(water extraction liquor, cooked liquor and cooked liquor concentrate) at 4 °C, the results show that water extraction liquor can be used for the preservation of shrimp.