Mechanical robust, pH responsive hemicellulose-based PVA film with barrier performance for fruit preservation and monitoring

Barrier films are essential for food packaging, but conventional solutions hinder the circular economy. This study introduces hemicellulose-based antioxidant crosslinked composite films as a sustainable alternative. We develop pH-responsive films (K-B/PVA/OA) using polyvinyl alcohol (PVA), silanized hemicellulose (KHC), blueberry anthocyanin (BA) as a pH indicator, and oxalic acid (OA) as a crosslinker. The films exhibit excellent oxygen and water vapor barrier properties and can be easily fabricated via solution casting with food-safe dispersions. The oxygen permeability ( OP ) decreases from 13.22 ± 0.65 × 10 −14 to 3.24 ± 0.98 × 10 −14  cm 3 ·μm/(m 2 ·d·Pa), and the water vapor permeability coefficient ( Pv ) drops from 15.43 ± 0.85 × 10 −13 to 7.27 ± 0.46 × 10 −13  g·cm/(cm 2 ·s·Pa). Tensile strength and modulus increase from 32.63 MPa and 765.80 MPa to 41.24 MPa and 1281.39 MPa. Esterification between PVA and hemicellulose raises surface energy, increasing the contact angle from 39.4° to 78.34°. Strawberries packaged in these films maintain their structure and exhibit a visible color change after 7 days, offering sustainable, real-time monitoring packaging.