Double-layered starch-based films containing citronella oil prepared by solution casting

The study aimed to determine the effect of drying time on the quality characteristics of the double-layer starch-based film and to evaluate the efficacy of citronella oil as a bioactive agent. The double-layered starch-based composite film was developed using a layer-by-layer solution casting method and dried for 15, 20, or 25 hours. The citronella oil as an emulsion was added as a bioactive agent to one layer (food contact surface) at different levels (0, 1, 3, and 5 %, w/w). The film was evaluated for various physico-mechanical characteristics, thermal stability and bioactive properties. The results showed a significant impact of the drying time on the physical characteristics of the film and the most optimum results were found for the film dried for 20 hours. The addition of citronella oil increased the thickness, water solubility, tensile strength, Young’s modulus and heat absorption of the film and decreased the WVTR and elongation at break. An effect of the concentration was found and the film containing the highest concentration (5 %) of citronella oil showed bigger-sized inhibitory halos and lower IC 50 values. Overall, this film proved to be effective in releasing citronella oil specifically on its inner active layer to inhibit microbial growth.