Physical properties of emulsified films based on chitosan and oleic acid

Abstract

Film-forming emulsions were formulated with chitosan (CH (g L−1): 7, 10, 15), oleic acid (OA (g L−1): 0, 3, 6) and glycerol as plasticizer (10 g L−1). The films were characterized on their physical properties (colour, water solubility, water vapour permeability and oxygen permeability (PO2)), in order to gain a better understanding of the functional properties of chitosan-lipid films. The incorporation of OA limited water vapour transfer in films obtained with 15 g L−1 CH, likely because the viscosity of the film-forming dispersion was high enough (η0 = 2.07 Pa s) to ensure the emulsion stabilization during the drying film process. The incorporation of OA did not generate significant (p > 0.05) differences of the PO2 values in the CH films; besides, they showed a slight yellow-green colour. The results of this study provide further evidence to promote the chitosan-lipid films to be used as biodegradable food packaging.