Citral Encapsulation to Chitosan-based Edible Films and Coatings Utilizing Nano-emulsion Approach

Active edible coatings may provide a natural safe and biodegradable alternative to synthetic preserving agent for prolonging shelf life of fruits and vegetables. In this study citral, a natural aroma and antimicrobial agent, was encapsulated to a chitosan-based coating formulation utilizing nano-emulsion approach. The properties and functionality of the nano-emulsions containing formulation were compared to those of the regular coarse emulsions containing formulations. DLS analysis showed that nano-emulsiosn had higher monodispersity than the coarse emulsion. The surface structure, seen from E-SEM studies was found to be more organized in edible films based on nano-emulsions. Encapsulation of citral generally impaired the mechanical properties of the films, however the negative effect of nano-emulsions is significantly smaller than that of the coarse emulsions. Moreover, nano-emulsions even increased the ‘elongation at break’ value. The water vapor permeability (WVP) of chitosan edible films was not significantly impaired by citral encapsulation. The effect of the active edible coatings was examined on fresh cut melons model. The nano-emulsions based coatings demonstrated advanced performance. The antimicrobial effect of the coatings was studied utilizing different concentrations of citral (0.8, 1.6, 2.4%). It was found that 1.6% and especially 2.4% citral significantly inhibited the microbial growth during all examination period (13 days).