Design of bio-based lignin-TiO₂/PVA composite films for active food packaging

The development of bio-based active functional additive materials for food packaging has emerged as a key area of research. Lipid oxidation in food products significantly compromises quality by inducing off-odors, rancidity, and eventual spoilage. To access this point, this study explores the practical application of a lignin-TiO₂ composite as an additive in packaging films. The Taguchi method, combined with grey relational analysis, was used to optimize lignin-TiO₂ composite for improving antibacterial, antioxidant, and UV-blocking properties. The 3% lignin-TiO₂/PVA film blocked 98.49% of UV light while maintaining 61.41% transparency, enhancing thermal management by reducing heat accumulation and keeping the temperature 1.33 °C lower than the bare film. Incorporation of 3% lignin-TiO₂ composite into the film was found to enhance barrier properties by creating complex pathways that restricted the permeation of water and oxygen molecules. Additionally, mechanical properties of the film improved, with tensile strength and elongation at rupture increasing by 14.09% and 8.95%, respectively. Moreover, the composite film effectively reduced lipid oxidation in lipid-rich foods, significantly delaying malondialdehyde (MDA) formation over a 30-day storage period and demonstrated biocompatibility with Vero cells, highlighting its potential for non-toxic application in food packaging. Overall, this study presents a promising strategy for extending the shelf life of food products while promoting the utilization of lignin, an otherwise wasted material, and contributing to environmental sustainability.