CITRAL ENCAPSULATION TO CHITOSAN-BASED EDIBLE FILMS AND COATINGS UTILIZING NANO-EMULSION APPROACH

Application of edible coatings for preserving fruits and vegetables after harvest is a well known alternative for the commercial synthetic wax. The purpose of this study, except for prolonging the shelf life, is also to improve the quality of the fresh produce by encapsulating natural active agents, like aroma compounds with antimicrobial activity, to a coating formulation based on chitosan. Citral is one example for such a material. We utilized the nano emulsion method as the encapsulation process and compared its properties with coarse-“regular” emulsion. Dynamic light scattering (DLS) analysis showed that formulation of citral in nano emulsion had higher monodispersity than the coarse emulsion, therefore the surface structure, seen from environmental scanning electon microscope (e-SEM) pictures, is seemed to be more organized in edible films based on nano emulsion. With respect to mechanical properties, encapsulation of citral impaired the elastic modulus of chitosan edible films, however nano emulsion based films affected less than the coarse emulsion and even increased the ‘elongation at break’ value. The water vapor permeability (WVP) of chitosan edible films was not impaired significantly by citral encapsulation. Further on in the study, we wanted to find the optimal concentration of citral (0.8, 1.6, 2.4%) in the nano-emulsion based chitosan coating that inhibits microbial growth on fresh-cut melon. We found that 0.8% citral encourages microbial growth while 1.6% and especially 2.4% inhibit the growth after 13 days.