Effect of Rosemary Oil and an Emulsion of Essential Oils on Structure and Physical Properties of Chitosan Film

Abstract

The objective of this work was to study the effect of Rosemary oil (Resemary Officinalis) and an emulsion at 68 % of EOs (EA3) on chitosan (CH) film forming dispersion (FFD) and CH films properties. FFD were characterized in terms of rheological properties and particle size distribution. In order to study the impact of EOs into the CH matrix, microstructure (SEM), film thickness, equilibrium moisture content (EMC) and water vapour permeability (WVP) of the dried film were evaluated. Results showed that oil concentration did not affect particle size distribution whereas the type of EO have an effect on the particle size dimension. The rheological properties of the FFD were significantly affected by the presence of the EOs. While a continuous structure was observed for the CH film, the presence of EOs caused discontinuities associated with the formation of two phases in the matrix: lipid droplets embedded in a continuous polymer network. The dimension of the oil droplet were higher in the film respect to the FFD. Moreover, it was showed that the higher the EOs content, the higher the film thickness and the lower the film moisture sorption capacity. The WVTR of CH film has an average value of 2.3x10-3 g m-2 s-1. The study revealed that an active chitosan film could be obtained by using the EA3 emulsion of EOs.