Nanolignin-infused biopolymer films from pine wood extracted using deep eutectic solvent: Investigation of UV-blocking efficiency, structural properties, and shelf-life extension of strawberry

Abstract

The development of sustainable active packaging materials with multifunctional performance remains a major challenge for food preservation applications. In this study, pine wood-derived nanolignin was extracted using deep eutectic solvents (DES), and the conventional Kraft process was incorporated into pectin-xanthan gum films to investigate the influence of lignin extraction chemistry on film functionality and strawberry preservation. DES-derived nanolignin exhibited a smaller particle size (255 nm), higher colloidal stability (_ 34.8 mV), and lower structural condensation than Kraft lignin, resulting in improved dispersion and stronger interfacial interactions within the polysaccharide network. Consequently, DES-lignin films demonstrated enhanced mechanical strength, reduced water vapor permeability, improved UV-shielding capacity, and superior antimicrobial activity. The DES1800 film exhibited the lowest water vapor permeability (1.22 & times; 10_6 mm/mm2 day kPa) and effectively inhibited microbial proliferation by reducing the survival of Escherichia coli, Staphylococcus aureus, and Candida albicans to 27.14%, 22.21%, and 17.73%, respectively. During refrigerated strawberry storage, DES1800 films reduced weight loss compared with the unwrapped control and effectively maintained physicochemical quality, color stability, and microbial safety over 12 days. The enhanced preservation performance was attributed to the high phenolic hydroxyl content, improved nanoscale dispersion, and stronger hydrogen-bonding interactions of DES-derived lignin, which collectively improved moisture barrier and antimicrobial functionality. These findings highlight the potential of DES-extracted nanolignin as a multifunctional bioactive nanofiller for sustainable food packaging applications.