Antimicrobial activity of chitosan edible coating enriched with aqueous extract of Withania coagulans fruit on the shelf life of Silver carp fillet stored in the refrigerator

Antibacterial packaging materials are nowadays considered as one of the new technologies to prevent the spread of spoilage and pathogenic microorganisms through food. The present study was conducted to investigate the antimicrobial effect of chitosan coating with the aqueous extract of Withania coagulans to increase the shelf life of silver carp (Hypophthalmichthys molitrix) fillet. Fish fillets were kept in 6 treatments and 3 replicates for 18 days at 4°C. Treatments included: uncoated treatments (control), 0.5% extract, 1% extract, 1% chitosan, 1% chitosan with 0.5% extract and 1% chitosan with 1% extract. The microbial characteristics [Total Bacterial Counts (TBC) and Psychrophilic Total Bacterial Counts (PTC)] of the samples were studied at 0, 3, 6, 9, 12, 15 and 18. During the storage period, all treatments containing chitosan coating and extract had significant differences in bacterial evaluation with control treatment (p<0.05). The highest bacterial indices of TBC and PTC up to day 18 of silver carp fillet storage in the refrigerator were in the control treatment (8.03 ± 0.02 and 8.16 ± 0.02) and the lowest in the 1% chitosan coating with 1% Withania coagulans extract (5.79 ± 0.01 and 6.10 ± 0.03), respectively.The results of current study showed the strong antibacterial effect of 1% chitosan edible coating with 1% whey extract which had a significant effect on the reduction of TBC and PTC and also increasing the shelf life of the coated fillets.