Abstract:

The purpose of this study was to optimize complex preservatives consisting of tea polyphenols, lysozyme and
chitosan using response surface methodology based on Box-Behnken experimental design to improve quality preservation
of pomfret fillets and prolong their shelf life. A quadratic polynomial regression model was established with total volatile
basic nitrogen (TVB-N) as the response value. The results indicated that the best formulation of complex preservative was
composed of 1.35% tea polyphenols, 0.054% lysozyme and 1.38% (m/m) chitosan by analysis of variance and regression
fitting. Tea polyphenols and chitosan, as well as lysozyme and chitosan had a significant interactive effect on the quality
of pomfret fillets during storage (P < 0.05). TVB-N, aerobic plate count (APC), thiobarbituric acid (TBA), trimethylamine
(TMA), pH and K value of pomfret fillets treated with the optimized complex preservative were determined and their sensory
scores were evaluated during storage at 4 ℃. The results showed that the optimal complex preservative could significantly
reduce the contents of TVB-N, TBA and TMA, and inhabit the growth of microorganisms (P < 0.05). Hence the complex
preservative could effectively delay the deterioration of pomfret fillets, prolonging the shelf life to 12 days compared to 5–6
days for the control group.

Key words: aquaculture, freshness preservation, response surface methodology, biopreservative, tea polyphenols, lysozyme, chitosan