Exploring lignin nanoparticle incorporation to develop multifunctional cellulose nanofibril films for active...

Films of cellulose nanofibrils (CNF) incorporating lignin nanoparticles (LNPs) were synthesized and evaluated for their potential as active and multifunctional packaging materials. The barrier and functional properties of the films (UV-blocking, antimicrobial, and antioxidant activities) were investigated alongside comprehensive chemical, morphological, mechanical, thermal, optical, and surface characterizations. LNPs self-assembled on the film surface during filtration-based dewatering, influencing surface roughness and wettability. However, LNP incorporation had minimal impact on bulk properties, preserving the mechanical strength (105-126 MPa), thermal stability (313-325 °C), and oxygen barrier performance (2.7-4.4 cc³.m^-2.day^-1.0.1 MPa^-1) provided by CNF. UV-blocking capacity (> 87 %) and antioxidant activity (8.55-27.89 RSA%) increased with higher LNP loading, while microbial growth assays suggested some antimicrobial effects, particularly at low LNP concentrations. LNP migration remained within regulatory limits for packaging materials (< 60 mg/kg), varying with lignin concentration and food simulant type. In food packaging simulations, CNF/LNP films outperformed commercial plastics, significantly extending the shelf life of raspberries. Overall, the incorporation of LNPs imparted unique functional properties to CNF films without compromising their structural integrity, demonstrating their strong potential for active packaging applications.