Intensification of yam-starch based biodegradable bioplastic film with bentonite for food packaging application

Bioplastics are gaining more attention over synthetic plastics owing to their nonhazardous properties. Earlier studies had reported the biodegradation and solubility properties of yam starch-based bioplastic; however, its mechanical properties with reinforcement were not studied. The present work focuses on the development of yam (Dioscorea) starch-based bioplastic film with glycerol as a plasticizer. Different concentrations of bentonite (0.5, 1, 1.5 %w/w) was reinforced and the biofilms were prepared by solvent casting method. The developed bioplastic films were systematically characterized using the scanning electron microscope (SEM), Fourier transforms infrared spectroscopy (FTIR), contact angle, tensile testing, soil and water degradation, water vapor transmission rate (WVTR), swelling, solubility, and chemical testing. The SEM micrographs show the bentonite particles were homogeneously distributed in the starch matrix. The hydrophilicity of the bioplastic was increased with the addition of bentonite. The FTIR spectra revealed that the addition of bentonite in the bioplastic film strengthened the O-H bond and Si-O-Si bond, which improved the mechanical strength. It was observed that 1.5% bentonite concentration exhibited maximum soil degradation rate and lowest water molecule absorption. This is due to the intercalated silicate layer of bentonite in the bioplastic films. Also, the bioplastic films with bentonite were more impermeable in salt and acidic medium but remained ineffective in the basic medium. The study revealed that bentonite concentration has effectively improved the yam starch-based bioplastic property, making it a potential bioplastic to replace synthetic plastic in food packaging applications. (C) 2021 Published by Elsevier B.V.