Sustainable, efficient graded extraction of chestnut burr polyphenols: Incorporating them into chitosan/polyvinyl alcohol active films to enhance grape preservation.

Abstract

In order to achieve high-value utilization of chestnut burr resources and develop novel food-active packaging materials, this study employed a green and sustainable method to extract polyphenols from chestnut burrs and incorporated them as functional components into chitosan/polyvinyl alcohol (CS/PVA) bio-based films. The propose of the study was to prepare two chestnut burr extracts with high polyphenol content: ice-water bath extract (CBEI, rich in gallic acid) and alkaline water ultrasonic extract (CBEA, rich in ellagic acid). Both extracts were incorporated into CS/PVA composite films at varying concentrations (1%, 5%, 10%), systematically investigating their effects on film color, thermal stability, barrier properties, mechanical properties, and bioactivity. Results demonstrated significantly enhanced physical, barrier, and mechanical properties of the composite films, with tensile strength reaching up to 9.29 MPa and elongation at break up to 293.76%, primarily attributed to the formation of a hydrogen-bonded dual-network structure. Additionally, the films exhibited outstanding antioxidant and antibacterial activity. In grape preservation experiments, films containing 10% CBEA (CPCA-3) effectively inhibited grape spoilage and significantly extended shelf life. This study provides a sustainable strategy for the stepwise extraction and high-value utilization of chestnut burr, laying the theoretical and technical foundation for developing CS/PVA active food packaging materials based on chestnut burr extracts.