Physicochemical, microstructural, antioxidant and antimicrobial properties of active packaging films based on poly(vinyl alcohol)/clay nanocomposite incorporated with tea polyphenols

Active poly(vinyl alcohol)/clay nanocomposite films incorporated with tea polyphenols (TP) was prepared by solution casting method. The effects of TP concentrations including 0%, 0.5%, 1%, 2%, 3% and 4% (based on dry weight of PVA) in the film-forming solution on the film properties were determined by measuring structural, physicochemical, mechanical, antioxidant and antimicrobial properties of the active films. X-ray diffraction (XRD) patterns and transmission electron microscopy (TEM) results showed that the MMT were well dispersed and mainly exfoliated in the PVA matrix. TP was well dispersed in the films as whole and no obvious aggregation was observed from scanning electron microscope (SEM) results. The results suggested that incorporation of TP into the films improved tensile strength, gas barrier (water vapor and oxygen) and water resistance properties. Fourier transforms infrared (FTIR) spectra indicated that interactions between TP and PVA were involved in the films. The antioxidant activity of the films was significantly improved and raised with increasing content of TP. It was demonstrated that these films incorporated with TP could inhibit bacterial growth. The antimicrobial capacity of the films against E. coli and S. aureus grew with increasing TP. This study revealed the benefits of incorporation of TP into the films and the potential application used as active packaging films or coating material to develop active packaging material.