Abstract: Chitosan/microcrystalline sterol composite edible films were prepared by flow casting method using chitosan as a film-forming material, where phytosterols were added for their antioxidant and antimicrobial properties. With increasing addition of phytosterols up to 12% (relative to the mass of chitosan), the tensile strength and elongation at break of composite films declined gradually, the solubility and swelling degree gradually increased, and the water vapour permeability coefficient remarkably reduced, indicating an improved moisture barrier property after the addition of sterol. In addition, the superoxide anion and hydroxyl radical scavenging capacities of films were improved remarkably, and the antimicrobial activity against Staphylococcus aureus and Escherichia coli were significantly enhanced. The compatibility of composite films was analyzed by infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD) and thermogravimetry (TG). The films with 9% sterol added showed good performance. Moreover, chitosan-sterol complexes were formed by strong intermolecular hydrogen bonding interactions, and the blend system had good compatibility.

Key words: chitosan, phytosterols, edible composite film, performance, structural characterization