Effect of nanochitosan coating enriched with or without green tea extract (Camellia sinensis L.) on physicochemical, microbial and sensory properties of Costal trevally fish (Carangoides coeruleopinnatus) during stored at refrigerator

In This study, comparative effects of nanochitosan coating enriched with or without green tea extract (Camellia sinensis L.) on quality of Costal trevally fish (Carangoides coeruleopinnatus) during refrigerated storage (4 °C) at 12 days. For this purpose, the costal trevally fillets were into three groups, immersed in nanochitosan (chitosan 2% and polyphosphate 2%), nanochitosan coated 0.5% green tea extract and acetic acid solution (control sample). Antimicrobial effects of nanochitosan coating (with or without green tea extract) evaluated by aerobic mesophilic counts and psychrophilic bacterial counts, using PCA. Physicochemical properties of samples have been investigated through, pH measurement, spectrophotometric evaluation of TBARS and TVB-N content determination using Kjheldal and titration of FFA method. Sensory evaluation determined by 15 panelists who were asked to evaluate the flavor, odor, overall acceptability in days (0, 3, 6, 9, 12), of the sample. The comparative of mesophilic count and psychrophilic count showed that the highest amount of TVC and PTC was obtained in control (5.11 and 4.43 log cfu/g) and the least amount of t mesophilic count and psychrophilic count had treatment immersed at nanochitosan coating enriched with green tea extract (4.10 and 3.70 log cfu/g). The results showed that change of physicochemical and bacterial were significantly (p<0/05) lowest in the samples treated with nanochitosan coating enriched with green tea extract as compared to control group (p<0.05). Also, TBA, FFA, TVBN and pH contents of fish fillet coated with nanochitosan and green tea extract was 0.42 mg malonaldehyde/ kg tissue, 1.46 % oleic acid, 19.40 mg N/100g sample and 7.49 that has the lowest contents comparison with other treatments (p<0.05). TMA content and SH content of control and coated with or without greaan tea extract showed no significant difference (p>0.05) at the end of storage. The results of sensory analysis showed that coated fillets had higher scores comparison with control sample. The results indicated that both nanochitosan coating enriched with geen tea extract were higher antimicrobial and antioxidan activity than nanochitosan during the storage period..Therefore, to extend  the shelf life and delay the deterioration of fresh costa trevally fillets during refrigerated storage, nanochitosan coating is more effective.