Fabrication of gallic acid crosslinked chitosan/poly(1-vinylpyrrolidone-co-vinyl acetate) antioxidant films for green chilli packaging

Abstract

In this study, chitosan (CS)/poly(1-vinylpyrrolidone-co-vinyl acetate) (PVP-co-VAc) films were fabricated by incorporating different weight fractions of gallic acid (GA), abbreviated as CPG, using the solvent casting method. The prepared films were investigated for their physicochemical properties. Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM) micrographs revealed the effective interaction between the added GA and the CS/poly(1-vinylpyrrolidone-co-vinyl acetate) polymer matrix. The resultant films demonstrated good barrier properties against water and oxygen, which were further supported by water contact angle (WCA) findings. Also, the films exhibited excellent mechanical properties with a tensile strength (TS) of 54.71 ± 0.62 MPa, which is more substantial than those of traditional polythene plastics (10–16 MPa). Compared with the CP film, the CPG-IV film with the highest weight percentage of GA exhibited a strong DPPH radical scavenging activity of 77.18% ± 0.020 and displayed vigorous antimicrobial activity against Staphylococcus aureus, Escherichia coli, and Candida albicans. Also, the packaging study revealed that chillies packed with the CPG-IV film containing the highest amount of GA showed a limited weight loss percentage in comparison with unpacked chillies and those packed with a polyethylene film over 14 days of storage. The above results suggested that the prepared films meet the essential requirements of green chilli packaging applications.