Antioxidant activity of chitosan edible coating enriched with aqueous extract of Withania coagulans fruit on chemical changes and sensory properties of silver carp (Hypophthalmichthys molitrix) stored in refrigerator

The present study was conducted to investigate the antioxidant effect of chitosan coating with the extract of Withania coagulans on chemical changes and sensory properties of silver carp fillet. Fish fillets were kept in 6 treatments and 3 replicates for 18 days at 4°C. Treatments included: control, 0.5% extract, 1% extract, 1% chitosan, 1% chitosan with 0.5% extract and 1% chitosan with 1% extract. The chemical factors and organoleptic properties of the samples were studied at 0, 3, 6, 9, 12, 15 and 18 days after storage in the refrigerator. During the storage period, all treatments containing chitosan coating and extract had significant differences in chemical factors and organoleptic properties evaluation compared to control treatment (p<0.05). The highest chemical indices of pH, PV, TBA and TVB-N up to day 18 of silver carp fillet storage in the refrigerator were in the control treatment [7.21±0.01, 6.70±0.04(meq/kg), 1.37±0.02(mg MDA/kg) and 38.69±0.01(mg/100g)] and the lowest in the 1% chitosan coating with 1% Withania coagulans extract [6.61±0.03, 3.17±0.02(meq/kg), 0.68±0.01(mg MDA/kg) and 18.43±0.03(mg/100g)], respectively. The total utility index of the treatment decreased in day 15 below the acceptability (3.82 ± 0.75), but the treatment with chitosan coating 1% and extract 1% had the highest total desirability score by the end of the period (4.77 ± 0.77). The results of the current study showed that the strong antioxidant effect of 1% chitosan edible coating with 1% whey extract, had a significant effect on the reduction of chemical changes and also increasing the sensory properties, extend the shelf life and delay the deterioration of silver carp the coated fillets.