Effects of tea polyphenols, lysozyme and chitosan on improving preservation quality of pomfret fillet

The purpose of this study was to evaluate the impact of different concentrations of tea polyphenols(A1: 0.1%(w/v), A2: 0.5%, A3: 1%), lysozyme(B1: 0.01%, B2: 0.05%, B3: 0.08%) and chitosan(C1: 0.5%, C2: 1%, C3: 2%, C4: 3%)on the quality of pomfret during;the storage in order to improve the quality of pomfret fresh preservation. The sensory evaluation, aerobic plate count(APC), trimethylamine(TMA), total volatile basis nitrogen(TVB-N), K value and pH value with different treatments were determined. The results showed that the shelf-life of the control group was 4 days under the cold storage, and the effect of fresh preservation was better with the increasing of the concentration of tea polyphenols, especially the APC could be significantly lower under the treatment groups of A2 and A3 than that under the control group from the 2nd day(P<0.05), the shelf-life was increased by 2 to 3 days. The treatments of B1 and B2 could restrain the increasing of gram-positive bacteria and reduced the contain of TVB-N, TMA-N and K value significantly(P<0.05), the shelf-life was increased by 1 to 2 days. The preservation effect of the treatment of C3 was better than those of control group and other groups with chitosan. The APC, TMA-N, TVB-N and K value could be significantly lower than those of the control group from the 2nd day, so the shelf-life was increased by 3 days. All of tea polyphenols and chitosan could improve the quality of aquaculture and prolong the shelf-life of pomfret by restraining the increasing of APC and the enzyme activity. The results will offer theory reference to the preservation of pomfrets and the application of bio-preservative.