Cassava starch films with green-synthesized ZnO nanoparticles from date palm pits for active packaging

Cassava starch-based nanocomposite films were developed by incorporating green-synthesized zinc oxide nanoparticles (ZnO NPs) from date palm pits. ZnO NPs (0-4 wt%) were synthesized using a plant-mediated approach and embedded into starch matrices. XRD, UV-Vis, FTIR, and SEM confirmed successful synthesis and uniform dispersion of hexagonal ZnO NPs (≈63.7 nm). The films exhibited enhanced UV-light shielding and reduced moisture content. At higher NP loadings, surface roughness and agglomeration increased, reducing tensile strength. Differential scanning calorimetry showed a decrease in glass transition temperature (92.8 °C to 85.0 °C), suggesting increased molecular mobility. Antimicrobial tests revealed strong, dose-dependent activity against Staphylococcus aureus and Bacillus cereus, but not Escherichia coli or the fungi Botrytis cinerea and Alternaria alternata, likely due to limited ZnO release and bacterial cell wall differences. These results demonstrate the potential of cassava starch/ZnO films as sustainable, antimicrobial packaging materials to extend the shelf life of perishable foods.