Biodegradable zein film composites reinforced with chitosan nanoparticles and cinnamon essential oil: Physical, mechanical, structural and antimicrobial attributes

Natural bio-based zein films were prepared by incorporating cinnamon essential oil (CEO) and chitosan nanoparticles (CNPs) at 2% and 4% (w/w) amounts, respectively, in order to provide mechanical and antimicrobial functionalities. The physical, mechanical, structural and antibacterial properties of the enriched zein films were also scrutinized. The results showed that the combination of CEO-CNPs significantly improves the tensile strength and decreases the elongation of zein film composite. According to X-ray diffraction (XRD) results, zein film experienced more crystallinity in the presence of CNPs and also combination of CNPs-CEO. Nano-scale size of CNPs and their uniform distribution within the zein film were monitored by scanning electron microscopy (SEM) and proved by dynamic light scattering (DLS) and transmission electron microscopy (TEM). The antimicrobial properties were investigated against Escherichia coli and Staphylococcus aureus, observing that their growth was considerably inhibited by addition of CEO alone and in combination with CNPs in zein films, while CNPs-loaded zein film had no significant effect on the growth of microorganisms. Thus, it can be concluded that the reinforced zein based composites could be suggested as potential degradable film-forming materials for food packaging applications.