In-situ lignin-integrated nanocellulose multifunctional composite films for fruit preservation applications.

Cellulose, one of the most abundant natural polymers on Earth, has attracted extensive attention in the field of food packaging due to its renewability, excellent mechanical strength, and environmental friendliness. However, the inherent hydrophilicity of cellulose limits its practical applications. Here, an innovative strategy was developed for nanocellulose modification by grafting ferulic acid onto the cellulose surface via Mitsunobu reaction, followed by in situ polymerization of lignin precursor. The resulting films exhibited a significantly improved water contact angle (74.8°) and tensile strength (26.32 MPa) compared to pure nanocellulose films. Meanwhile, compared with pure nanocellulose films, the water vapor permeability of the films decreased by 42.1%, while the antioxidant activity increased to 77.4%. Moreover, the composite film effectively extended the postharvest shelf life of cherry tomatoes. Given its multifunctionality, this bio-derived composite film demonstrates great potential as a sustainable alternative to conventional plastics in active food packaging and other environmentally conscious applications.