Bacterial cellulose and photothermal material from biomass-based zero-waste biorefinery functionalized chitosan film for sustainable active food packaging

In this study, a multifunctional food packaging film was developed using distillers' grains (DG) through a sustainable, zero-waste biorefinery approach. The objectives were to reduce foodborne contamination, lower manufacturing costs, and enhance the value of DG. Bacterial cellulose (BC) was produced by fermenting the hydrolyzed DG supernatant and then oxidized to form oxidized bacterial cellulose (OBC). OBC was combined with chitosan (CS) to create a CS/OBC composite film. Additionally, a photothermal material, FeDL, was synthesized from DG's enzymatic residue (primarily lignin) and ferrous sulfate heptahydrate. Various concentrations of FeDL were incorporated into the CS/OBC matrix. Characterization using scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and thermal analysis confirmed good compatibility between FeDL and CS/OBC, with slight improvements in thermal stability and tensile strength (TS). The film containing 0.3 mg/mL FeDL achieved a 37.21% reduction in UV transmittance, a 26.81% decrease in water vapor permeability (WVP), and a 175.08% increase in antioxidant activity compared to the CS/OBC film. Under brief near-infrared light (NIR) exposure, the film enabled pasteurization, extending the shelf life of strawberries by approximately 1.75 times. The films also demonstrated biosafety and biodegradability, offering a novel zero-waste biorefining solution from waste biomass.