Quality and shelf life extension of refrigerated Oncorhynchus mykiss fillets: Comparison of the double layer and monolayer edible biogenic gelatin-chitosan coating incorporated with Origanum vulgare essential oil, nisin, EDTA

This study aimed to compare monolayer and bilayer biodegradable edible coating incorporated with gelatin (3% w/v), chitosan (1% w/v) and Origanum vulgare essential oil (30 mg/l) in Oncorhynchus mykiss fillets during 16 days of refrigerated storage. Nisin (10,000 IU/g) and ethylenediaminetetraacetic acid (0.16% w/w) were used to increase the antimicrobial properties and reduce the organoleptic changes caused by essential oils in the food. Characterization of these two coatings was evaluated through microbial analysis (total viable bacterial count, lactic acid bacteria, Enterobacteriaceae, specific spoilage organisms), chemical analysis (essential oil analysis, sample approximate analysis, pH, total volatile basic nitrogen, peroxide value, free fatty acids, thiobarbituric acid reactive substances) and sensory analysis. Results showed an increasing trend in bacterial growth pattern. The bacterial load in the control treatments was above the permissible limit. Bacterial load was significantly lower in monolayer fillet coatings than bilayer fillets (p<0.05). There was an increasing trend in total volatile basic nitrogen and free fatty acid index in the control treatments than in the treated sample (p<0.05). Samples with monolayer coating had lower peroxide and thiobarbituric acid content than those with bilayer coatings. The monolayer coating was able to reduce the lipid oxidation in fillets (p<0.05). Results of sensory analysis of monolayer-coated samples showed improvement in fish quality during storage. Thus, gelatin-chitosan monolayer coatings containing nisin, EDTA and Origanum vulgare essential oil can be used as an active packaging and a safe preservative for fish.

Quality and shelf life extension of refrigerated Oncorhynchus mykiss fillets: Comparison of the double layer and monolayer edible biogenic gelatin-chitosan coating incorporated with Origanum vulgare essential oil, nisin, EDTA Keywords:

Edible biogenic coating , Origanum vulgare essential oil , Nisin , Ethylenediaminetetraacetic acid