Preparation and characterization of carboxymethyl-gellan and pullulan blend films

Abstract

This manuscript described the detailed characterization of edible films made from two different polysaccharides - carboxymethyl-gellan (CMGe) and pullulan (Pu), added with glycerol. CMGe/Pu blend films with different ratios were developed, and their effects on films' physical properties were assessed. Fourier transform infrared (FTIR) spectroscopy techniques, thermogravimetric analysis (TGA), X-ray diffraction (XRD), and Scanning electron microscope (SEM) were used to highlight the interaction between the two polysaccharides. The results suggested that the interactions between CMGe and Pu existed, indicating that this two polymers had excellent blend miscibility. Moisture sorption isotherms were also studied and Guggenheim-Anderson-de Boer (GAB) sorption models were tested to fit the experimental data. Changes in the sorption parameters, particularly such as the decrease in monolayer moisture content (Mo), reflected the trend of reduced hydration capacity with increased addition of Pu. The addition of Pu to CMGe improved the elongation at break (EAB), decreased the tensile strength (TS), decreased values of water vapor permeability (WVP) leading to an improvement of barrier properties of the films. Therefore, different CMGe/Pu ratios could be used to tailor edible films with enhanced barrier and mechanical properties.