Advanced biodegradable starch-based nanocomposite films incorporating zinc oxide nanoparticles: Synthesis, characterization, and efficacy in antibacterial food packaging applications

This study explores the development of biodegradable packaging system incorporating Zinc oxide nanoparticles (ZnO NPs) at concentrations of 1 %, 2 %, and 3 % within a starch matrix. ZnO nanoparticles improve starch biofilms' mechanical properties by strengthening their structure, tensile strength, and durability. As the concentration of ZnO nanoparticles increases, they fill the gaps between starch molecules, making the films more robust and rigid. Additionally, they act as heat-resistant fillers, extending the films' thermal endurance. We created cost-effective, sustainable, chemical-free, and biodegradable biofilms for food packaging. After being treated with ZnO nanoparticles, these films showed improved mechanical, antibacterial, and UV barrier qualities. The antibacterial action arises from the generation of reactive oxygen species (ROS), which damage bacterial cells. ZnO NPs also provide UV protection by absorbing and scattering harmful UV radiation, thanks to their wide bandgap and high surface reactivity. The FESEM clearly showed that the Starch glycerol biofilms consist of ZnO nanoparticles. The WVP increased significantly from 1.16 g mm/m2 day kPa (pure starch film) to 2.25 g mm/m2 day kPa upon the addition of nano-ZnO. This occurred because the film's thick structure was broken, which accelerated the penetration of water molecules. When ZnO nanoparticles were introduced at higher concentrations (>= 1 %), the tensile strength increased dramatically; values rose from 6.2 MPa in pure starch films to 25.1 MPa at 3 % ZnO nanoparticle inclusion. Furthermore, there was no detectable antibacterial effect from the starch films. Minimum Inhibitory Concentration (MIC) values for S. aureus (28) and E. coli (29), which assesses antibacterial activity. These films were subsequently used to package grapes and tomatoes, with the quality of both wrapped and unwrapped produce assessed based on pH, TSS and acidity. This packaging effectively increased the food's shelf life. In four weeks, starch glycerol biofilms incorporated with ZnO nanoparticles decompose naturally.