EFFECTS OF COATINGS OF POLYETHYLENEIMINE AND THYME ESSENTIAL OIL COMBINED WITH CHITOSAN ON SLICED FRESH CHANNA ARGUS DURING REFRIGERATED STORAGE

The coating effects of polyethyleneimine (PEI) and thyme essential oil (T) combined with chitosan (Ch) on the quality of sliced fresh Channa argus during refrigerated storage at 41C were investigated. Solutions of Ch, Ch+PEI (2% w/v Ch+1% v/v PEI) and Ch+T (2% w/v Ch+1% v/v T) were used as coatings. The treatments were compared by analyzing changes in sensory characteristics, total viable count and physicochemical parameters (texture, pH, thiobarbituric acid and total volatile basic nitrogen). The results indicated that all three treatments retarded the decay of the fish fillets and significantly extended the shelf life by approximately 4-5 days compared with control treatment (without treatment). Based on microbiological, physicochemical and sensory evaluations, the Ch/PEI treatment exhibited superior preservation ability in maintaining the quality of C.argus among the three treatments. And the preservation ability of the Ch/T treatment was better than that of the Ch treatment. Practical ApplicationsIn the recent years, people have paid more attention to health and food quality throughout the world. Bacterial contamination reduces the shelf life of fish products. In order to meet the consumers' demand, the antibacterial coating has been applied to the field of food. This paper gives a report on the changes of quality of Channa argus treated with coatings of polyethyleneimine (PEI) and thyme essential oil combined with chitosan. From the results obtained, C.argus without treatment deteriorates much quicker than samples treated with coatings because of antimicrobial action of coating solution, and PEI combined with chitosan has the best effect on maintaining the quality. The outcome demonstrates that the combination of PEI and chitosan is significantly effective in limiting microbial spoilage in sliced fresh C.argus and enhancing the shelf life. This work will provide useful information for fish preservation.