Fabrication and characterization of the bionanocomposite film based on whey protein biopolymer loaded with TiO2 nanoparticles, cellulose nanofibers and rosemary essential oil

A bionanocomposite film based on whey protein isolate (WPI), cellulose nanofibers (CNFs), titanium dioxide (TiO2) nanoparticles and rosemary essential oil (REO) was prepared by casting/evaporation method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR). The effects of various concentrations of CNFs (2.5, 5, 7.5 and 10%), TiO2 (0.5, 1 and 1.5%) and REO (1.5 and 2%) were investigated on the physicomechanical, barrier analyses, antibacterial, and antioxidant properties of bionanocomposite films. The results showed that the simultaneous combination of mineral compounds (TiO2) and phytochemicals (REO) with WPI/CNFs films had remarkable effects on the studied properties. Water resistance of WPI/CNFs composite films increased significantly with the addition of TiO2 and REO. The results of FTIR spectroscopy showed suitable interactions between TiO2 and REO with WPI/CNFs blend, while the results of SEM confirmed good and homogeneous dispersion of TiO2 NPs into the films. Addition of CNFs (7.5%) and TiO2 (1%) has led to a significant increase in tensile strength (TS) and Young's modulus (YM), while elongation at break (EB) reduced. However, the addition of REO, regardless of TiO2 nanoparticles addition, decreased TS and YM, EB significantly increased. In addition, WPI/CNFs7.5% films that have been incorporated with both TiO2 and REO, had shown lower EB and higher TS and YM. On the other hand, TiO2 and REO incorporation reduced transparency and increased hydrophobicity of WPI/CNFs films. Simultaneous combination of TiO2 and REO into WPI/CNFs films, showed a strong antibacterial activity against pathogenic and spoilage bacteria, especially Gram posetive bacteria. The developed films exhibited good morphology features, improved physicomechanical properties and appropriate antibacterial and antioxidant behavior due to the excellent dispersion of the TiO2 and REO into the WPI/CNFs matrix, which are the important properties required for packaging applications. Finally, the results propose for the use of CNFs as a green reinforcement and good replacement for mineral reinforcement and use of these ecofriendly nanocomposite films in packaging industries.