Development of ZnO Nanoparticle-Embedded Waste-Derived Polysaccharide–Protein Biocomposite Films with Enhanced Antimicrobial Activity and Food Preservation Efficacy

Abstract Nature has sustained life on Earth through inherently balanced and biodegradable systems. Inspired by these natural processes, this study employed waste valorization to develop biodegradable biopolymer films by integrating natural polymer components through supramolecular interactions. To achieve this objective, banana peel waste and corn peel waste were utilized as sustainable resources and combined with gelatin to fabricate a biodegradable banana peel-corn peel-gelatin (BCG) film. Zinc oxide NPs (ZnO NPs) fabricated in a greener way were incorporated into the biomatrix to develop a ZnO-reinforced nanocomposite film (ZnBCG) with enhanced functional properties. The developed films were systematically characterized using UV–Visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), thermogravimetric analysis (TGA), dynamic mechanical analysis (DMA), and tensile strength measurements. The incorporation of ZnO nanoparticles improved the optical shielding ability, surface characteristics, mechanical flexibility, and thermal behavior of the BCG matrix through improved nanoparticle–polymer interactions. Furthermore, ZnBCG exhibited enhanced antimicrobial, antioxidant, and anti-inflammatory activities compared with the pristine BCG film. Soil burial studies confirmed the environmentally benign nature of the developed films under natural conditions, while grape preservation experiments demonstrated their potential for extending grape shelf life over a 10-day storage period. Overall, the ZnO-reinforced waste-derived biopolymer film represents a sustainable active packaging material with combined structural, functional, and environmental advantages.