Use of Aloe Vera-based Edible Coating Containing Nanoemulsion of Ginger Essential Oil to Extend Trout Fillet Shelf-life

Background and Objectives:  Edible coatings containing natural antimicrobial compounds are appropriate approaches to control the microbial growth and thus improve the quality and shelf-life of fresh, frozen and processed fish products. The aim of this study was to assess effects of aloe vera gel coating containing nanoemulsion of ginger essential oil to extend the shelf life of trout fillets during 12 days of storage in refrigerator (4° C).  Materials and Methods: To achieve the optimal nanoemulsion by ultrasonic method and solve Ostwald ripening phenomenon in nanoemulsions, lecithin was used in concentrations of 0, 0.5 and 1% (w/w) and Tween 80 in concentrations of 5 and 10% (w/w). Results: Analyses of particle size, zeta potential and polidispersity indices showed that the prepared nanoemulsions with 10% of Tween and 1% of lecithin included high stability scores and were assessed as the optimal nanoemulsion to extend the shelf life of trout fillets. The coatings containing essential oil nanoemulsion and pure essential oil significantly (p < 0.05) decreased total aerobic mesophilic count, psychrotrophic bacteria, Enterobacteriaceae and lactic acid bacteria compared to the control. Furthermore, spoilage changes were observed earlier in control and aloe vera coatings compared to other treatments. While the coating containing the essential oil nanoemulsion could significantly (p < 0.05) increase the trout fillet shelf-life by controlling microbial and chemical changes compared to other treatments. Furthermore, sensory evaluation showed that the overall acceptability for the nanoemulsion coating was satisfactory during the storage period under cold conditions. Conclusion: Results of this study verified that ginger essential oil was appropriately encapsulated in the nanoemulsion and increased antimicrobial and antioxidant characteristics could extend the shelf life of fish fillets.