Comparative effects of chitosan and nanochitosan coatings enriched with green tea)Camellia sinensis L.( extract on quality of Costal trevally fish (Carangoides coeruleopinnatus) during refrigerated storage

In this study, comparative effects of chitosan and nanochitosan coatings enriched with green tea extract were analyzed on quality of Costal trevally fish (Carangoides coeruleopinnatus) during refrigerated (4±1 ºC) storage at 12 days. For this purpose, the costal trevally fillets were coated into three groups, 2% chitosan solution containing 0.5% green tea extract, nanochitosan (2% chitosan, 2% polyphosphate) containing 0.5% green tea extract and acetic acid solution as control sample. Antimicrobial effect of chitosan and nanochitosan coatings enriched with green tea extract was evaluated by count of aerobic mesophilic bacteria and psychrophilic bacteria, physicochemical properties including pH, TBARS, TVBN and FFA. Sensory evaluation determined by 15 persons who asked to evaluate the flavor, odor, overall acceptability of samples in days 0, 3, 6, 9, 12. The results of physicochemical and bacterial analysis showed that samples treated with chitosan and nanochitosan coatings enriched with green tea extract were lower changes compared to control group. TVB-N, FFA, TBA and pH content in the samples of chitosan and nanochitosan coatings enriched with green tea extract were 20.30, 19.40 mgN/100g, 1.46, 1.05 % Oleic acid and 0.66, 0.42 mg MDA/kg and 7.61, 7.49, respectively. The results of sensory characteristics were showed that treated fillets had high score compared to control samples. Both chitosan and nanochitosan coatings were effective for the preservation of costa trevally fillets during refrigerated storage. However, nanochitosan exhibited higher antimicrobial and antioxidant activity than chitosan during the storage period. Therefore, to extend the shelf life and delay the deterioration of fresh costal trevally fillets during refrigerated storage, nanochitosan coating is more effective.