Penaeus Vannamei Quality Evaluation And Classiifcation Technology

China’s shrimp catching amount in the world is in the first place. Penaeus vannamei is accounted formore than84%in Chinese shrimp market. The thesis comprehensive studies the quality indices Penaeusvannamei during storage. The changing of cooled and chilled whole and peeled shrimp’s quality indiceswith days was studied. The getting datum was analyzed by SAS software. We optimized the indices andchoose optimized11quality indicators as final indices to evaluate and grade the shrimp through qualityindex method (QIM). The conclusions of this thesis as following:(1) The chemical indices’ changing law of cooled and chilled whole and peeled shrimp: pH value (aslight decrease of chilled sample in the second assay point), TVB-N value, electrical conductivity, IMPand HxR content are increasing with the storage days; crude protein content, muscle fiber protein, Ca2+-ATPase’ activity, ATP and ADP content are decreasing with the storage days; activity of PPO enzymeand amino acid nitrogen content have slight decline in the initial and then upward; TBARS value hasbeen on the rise, but a slight decline before the end of storage is found; K value and Hx content is risingon the early stage and then to keep on a relatively stable value; sulphydryl content and AMP contenthave lower value in the early and late stage with the highest peak value in the middle storage period.The physical indices’ changing law: the value of the hardness, elastic index, chewiness, cohesive andadhesive of texture’ indices are decline with the increase of storage day, while adhesion value rise inprevious-medium period and decline in late stage; L value rise in the early stage and drop in late stage;sensory evaluation scores are increase with the growth of storage day. The total number of colonies ofhygiene indices is slightly increases with the increase of storage day.(2) Volatile substance of cooled and chilled whole and peeled shrimp is determined and we findvolatile compounds mainly including alcohols, aldehydes, ketones, hydrocarbons, esters andnitrogen-containing heterocyclic compounds; the alcohol peak area of cooled sample is about18.4%,while chilled is14.6%; aldehydes are mainly4,6,8,9,10carbon aldehydes; hydrocarbons focus onalkane, alkene and less alkyne, with less than10carbon. In non-volatile substances, the shrimp musclehas higher levels Gly, Arg, Ala, Val, Hyp and Pro amount, accounting for90%to total free amino acidcontent; non-volatile flavor compounds of nucleoside see the conclusion (1) of ATP and its relatedcompounds’ variation.(3) In the investigation of the sensory evaluation of QIM, the weights of sensory indicators, physicaland chemical indicators and other indicators were0.42,0.35,0.23respectively; in the sensory indicators,appearance, color, smell, taste and flavor were0.30,0.27,0.17,0.26respectively; in physical andchemical indicators, PPO values, ATPase, TBA value, amino acid nitrogen content, ADP content,TVB-N value, pH, and texture were0.18,0.10,0.06,0.14,0.10,0.20,0.12,0.10respectively; in otherindicators, microbial indicators and the other right were0.65,0.35respectively. Sensory evaluation teamassess the sub-class sensory indicators of whole and peeled shrimp, with sum score of16points and9 points respectively, and find the scores rise with the increase of storage day.(4) Through principal component analysis and cluster analyzing the indices of whole and peeledshrimp, we ultimately determine11parameters to grade shrimp. Using selected indicators to setassessment model, we carry quality rating calculation combined with the QIM weight. Final shrimp aredivided into five grades.