Characterization and antibacterial properties of biodegradable films based on CMC, mucilage from Dioscorea opposita Thunb. and Ag nanoparticles

The biodegradable films, composed of carboxymethyl cellulose (CMC), glycerol, mucilage from Dioscorea opposita (DOM) and Ag nanoparticles, were prepared by a casting method and characterised including colour measurement, solubility, mechanical and water barrier properties etc. to fit the requirements for food packaging. The films were also analysed by fourier transformed infrared spectroscopy, thermal analysis, scanning electron microscopy, and rheometer etc., meanwhile, the antimicrobial activities and acute toxicity of the films were investigated. The addition of Ag nanoparticles and DOM decreased the tensile strength, water solubility and transparency value, while increased the elongation at break. The functional groups and thermal analysis of films presented no significant differences, and the film-forming solutions showed similar shear-thinning properties. Antimicrobial evaluation revealed that the films achieved significant antibaterial effects against both Gram-positive (S. aureus) and Gram-negative (E. coli) bacteria. The biodegradable films presented a compact and uniform structure with antibacterial properties and without toxicological responses, which has excellent potential to be applied in food packaging.

Keywords: Ag nanoparticles; CMC; Chinese yam; Mucilage.