Development and characterization of bacterial cellulose reinforced biocomposite films based on protein from buckwheat distiller's dried grains.

Biocomposite films were manufactured by combining protein extracted from buckwheat distiller's dried grains with bacterial cellulose (BC). The film microstructures showed that BC is compatible with protein matrix and endows the film with high rigidity. Differential scanning calorimetry (DSC) showed that BC can promote thermal stability of the composite films. BC promoted the transition from a Newtonian to a non-Newtonian fluid and the shear thinning behavior of protein-BC solution. Fourier Transform Infrared (FTIR) spectroscopy showed the main functional groups' absorption peaks shifted to lower wavenumbers. Results of both FTIR and viscosity analysis proved the formation of intermolecular interactions through hydrogen bonds. These bonds affected film characteristics such as moisture content (MC), water solubility (WS), and water vapor permeability (WVP), which decreased with addition of BC. The WVP (6.68±0.78-5.95±0.54×10-10gm/Pasm2) of the films were lower than other protein films. Tensile strength (TS) values of films containing 1.8% and 2.0% BC (14.98±0.97 and 15.03±2.04MPa) were significantly higher than that of pure protein films (4.26±0.66MPa). Combination of proteins extracted from a waste product and BC led to composite films with low water vapor permeability and excellent mechanical properties.