Effect of molecular weight and drying temperature on the physicochemical properties of chitosan edible film

Background: Chitosan is the second most abundant polysaccharide abundant in nature after cellulose. In this study chitosan edible films with three different molecular weights (low [LMW], medium [MMW] and high [HMW] molecular weights) were prepared by drying them at room (21 degrees C), 40 and 50 degrees C and their physicochemical properties were characterized. Results: Molecular weight had a positive effect on the thickness, tensile strength (TS), elongation at break (EAB) and swelling ability (SA) of the films. However, film solubility(S) and water vapor permeability (WVP) were negatively affected. Higher drying temperatures increased the TS of the films whereas lower drying temperatures increased the MC, S, WVP and the EAB of the films. All the films prepared were transparent; however, films made with LMW chitosan were yellowish color. FTIR spectra of the films were influenced by the molecular weight of chitosan and the drying temperature, which revealed that there was an interaction between MW and the drying temperature. Conclusion: This study demonstrated that films made with medium MW chitosan by drying at room temperature had the most favorable properties for food packaging applications.