Antioxidant and antifungal effects of eugenol incorporated in bionanocomposites of poly(3-hydroxybutyrate)-thermoplastic starch

Traditional food packaging materials (e.g., polypropylene and polyethylene) serve to isolate foods from the environment. For this reason, there is growing interest in developing active food packaging materials that can extend shelf-life and interact with foods, which could also counteract the level of contamination by plastic in the environment using biodegradable polymers as packaging materials. For this purpose, poly(3-hydroxybutyrate) (PHB)-thermoplastic starch (TPS)/organically modified montmorillonite (OMMT)/eugenol bionanocomposites were prepared by melt blending. Morphological, thermal and mechanical properties were determined by comparing the influence of the eugenol and clay on the PHB-TPS blend and PHB. The X-ray diffraction (XRD) diffractograms and Transmission electron microscopy (TEM) micrographs indicated that the morphology of the bionanocomposites were intercalated-exfoliated. The presence of additives did not affect the decomposition temperature of PHB, but if the melting temperature decreased by approximately 10 degrees C, the degree of crystallinity increased with respect to PHB. Tensile test indicated that the elastic modulus decreased by 25% for the PHB-TPS (65:35) blend, while for the PHB-TPS (65:35)/OMMT bionanocompuestos increased by 12%, compare to pure PHB. Finally, bionanocomposites with eugenol exhibited antifungal activity against Botritys cinerea and antioxidant activity, as indicated by high percentages of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical removal. This study showed that bionanocomposites with eugenol could be used as food packaging materials.