Thermoplastic starch-ZnO nanocomposites: A comprehensive review of their applications in functional food packaging

The increasing demand for environmentally friendly food packaging solutions has driven extensive research into biodegradable materials, particularly thermoplastic starch (TPS), which is an eco-friendly alternative to petroleum-based plastics. Despite its eco-friendly attributes, TPS exhibit limitations, including inadequate mechanical and thermal properties, high water sensitivity, and insufficient antibacterial activity. Although strategies such as chemical modification, blending, and the use of compatibilizers have been employed to enhance TPS for packaging applications, they often fail to address the fundamental material deficiencies. The incorporation of zinc oxide (ZnO) nanoparticles is a complementary strategy that significantly improves the mechanical strength, thermal stability, and antimicrobial properties of TPS. This review focuses on TPS-ZnO nanocomposites, a promising subcategory of bio-nanocomposites recognized for their enhanced functional properties in food packaging applications. It highlights the renewability, biodegradability, and processability of TPS while also examining the synthesis and characterization of TPS-ZnO nanocomposites, particularly their mechanical, thermal, antimicrobial, and antioxidant properties. The synergistic effects of TPS and ZnO nanoparticles yield composites with functional characteristics that enhance food preservation and extend the shelf life. Furthermore, this review explores the various applications of TPS-ZnO nanocomposites in active, intelligent, and sustainable food packaging, emphasizing their potential to address the pressing challenges of food waste and environmental impact.