Sustainable lignin-curcumin functionalized PVA films crosslinked with citric acid for cherry tomato preservation.

Biodegradable active packaging is urgently needed to mitigate food spoilage and plastic pollution. In this study, polyvinyl alcohol (PVA) films were reinforced with alkali lignin (AL), crosslinked by citric acid (CA), and functionalized with curcumin (Cur) to integrate structural stability with bioactive functionality. The synergistic modification generated a compact and stable polymer network, leading to significant enhancements in mechanical strength and barrier performance compared with neat PVA. Furthermore, curcumin endowed the films with strong antioxidant, antimicrobial, UV-shielding, and pH-responsive colorimetric properties, while maintaining biodegradability. When applied to cherry tomato preservation, the composite films effectively reduced weight loss, maintained firmness, preserved nutrients, and delayed browning. Together, these effects significantly extended shelf life under ambient storage. This work demonstrates a synergistic strategy that transforms PVA into an active multifunctional packaging material, providing a green pathway for developing sustainable PVA-based films.