Thermoplastic starch-based films loaded with biochar-ZnO particles for active food packaging

Foods with extended shelf life motivate the development of active packaging materials. The addition of functional fillers to polysaccharide-based films is a promising approach. In this line, biochar-ZnO (C–ZnO) composites were obtained from sucrose and glucosamine pyrolyzed in the presence of ZnO particles, resulting in Suc-ZnO and GlcN-ZnO composites, respectively. The influence of different amounts (10%, 30%, and 50 wt%) of C–ZnO structures on the properties of thermoplastic starch-based films was studied, demonstrating that 50 wt% of C–ZnO decreased by 30% the film's water solubility while its stiffness increased by 1.5 times. The highest GlcN-ZnO content allowed to obtain the best electrical conductivity (6.7 × 10−4 S/m), antioxidant activity (around 70% of ABTS•+ inhibition in 8 h), and antibacterial activity against Escherichia coli and Staphylococcus aureus. These starch/C–ZnO films showed the potential to extend food shelf life as a promising active and electrically conductive food packaging system.