Abstract: In order to improve the dispersion of zinc oxide (ZnO) nanoparticles in konjac glucomannan (KGM)-based films, and enhance the anti-ultraviolet (UV) and antibacterial properties of nanocomposite films, ZnO nanoparticles modified with oleic acid (OAZnO) was used to prepare KGM/OAZnO nanocomposite films by a casting method, and the effects of OAZnO on the structure and physicochemical properties of KGM-based films were studied by rheological analysis, Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), microstructural observation, thermogravimetric analysis (TGA) and physicochemical measurements. The results showed that oleic acid (OA) improved the dispersity of ZnO nanoparticles. The FTIR analysis confirmed the formation of strong hydrogen bonds between ZnO nanoparticles and KGM. The XRD spectra showed that Zn2+ in ZnO nanoparticles formed coordination bonds with –OH on the KGM chain. Meanwhile, the appropriate amount (0.49 mL) of OAZnO nanoparticles enhanced the packaging-related mechanical and water barrier properties of nanocomposite films, decreasing water vapor permeability (WVP) by 35.62% and increasing tensile strength by 79.26% when compared with those of KGM films. In addition, KGM/OAZnO nanocomposite films had strong UV barrier and antibacterial properties. Therefore, addition of OAZnO especially at 0.49 mL could improve the overall performance of nanocomposite films, making it a candidate for use as a functional food packaging film to extend the shelf life of packaged foods.

Key words: konjac glucomannan; oleic acid; zinc oxide nanoparticles; antibacterial properties; nanocomposite antibacterial film