Abstract: In order to develop sustained-release films with excellent performance, this study used polyvinyl alcohol (PVA) and chitosan (CS) as a film-forming substrate, β-cyclodextrin (β-CD) as a sustained-release agent, and oregano oil (OEO) as an antibacterial and antioxidant to prepare β-CD/CS/PVA composite films with different amounts of added OEO. The effects of addition of different amounts of OEO on the basic properties, physicochemical structure, antibacterial and antioxidant properties, and slow-release performance of the composite films were investigated. Fourier transform infrared (FTIR) spectroscopy indicated that none of the components altered the structure of the composite film. Increasing the content of OEO improved the ductility, hydrophobic properties, and light barrier properties, and also significantly increase the antibacterial and antioxidant capacities (P < 0.05). The diameters of inhibition zones of the composite film with 2% OEO against Staphylococcus aureus and Escherichia coli was 8.42 and 9.24 mm, respectively, and its DPPH radical scavenging rate was 80.84%. The composite film had excellent sustained-release performance in 95% ethanol, and the active substance in the composite films with 0.5% and 1.5% OEO could be released continuously for 540 min in this medium. It was concluded that the composite film with 2% OEOs had good overall performance, showing great potential for development.

Key words: polyvinyl alcohol; chitosan; oregano oil; β-cyclodextrin; sustained release