Optimization of antibacterial and physical properties of chitosan/citronella oil film by electrostatic spraying and evaluation of its preservation effectiveness on salmon fillets

Response surface methodology was applied to optimize the effect of different concentrations of chitosan (CH), citronella oil (CNO) and surfactant tween 80 (TW) on antibacterial and physical properties of edible films prepared by electrostatic spraying (ES). In addition, the preservation effectiveness of the optimal formulation (OF) on salmon fillets was evaluated over a 10-day storage at 4 °C. Physicochemical and microbiological properties of salmon fillets were analyzed during storage. Results showed that TW contributed to the decrease of droplet size during ES, and antibacterial property was mainly attributed to CNO. The OF were obtained at CH concentration of 0.50%, CNO concentration of 0.50% and TW concentration of 0.30%, which improved the storage quality of salmon fillets (P < 0.05). The total number of bacteria of the uncoated salmon sample was 6.42 log CFU/g at day 10, while the value of OF treated group was 4.78 log CFU/g. The thiobarbituric acid (TBA) and total volatile basic-nitrogen (TVB-N) contents of the OF treated samples were only 38.4% and 48.6% of the values of the control sample, respectively. The OF treated group also retains better hardness and color at the end of storage. It was indicated that CH-essential oil coating applied by ES was effective for the preservation of salmon fillets. • Chitosan (CH)/citronella oil (CNO) coating was prepared by electrostatic spraying. • Antibacterial property of coating was mainly attributed to CNO. • Optimal coating formulation improved the storage quality of salmon fillets. • Addition of surfactant tween 80 (TW) contributed to the decrease of droplet size. • Optimal coating formulation contained 0.50% CH, 0.50% CNO and 0.30% TW.