Preparation and Characterization of Soy Protein Isolate Films Incorporating Modified Nano-TiO2

Abstract

Abstract Antimicrobial films were prepared by incorporating nano-titanium dioxide (TiO2) modified by silane into soy protein isolate (SPI) films. The effects of different concentrations of modified nano-TiO2 (TiO2-NM) on the physical properties, antimicrobial properties, and microstructure of the SPI-based films were investigated. Attenuated total reflectance Fourier-transform infrared spectroscopy indicated that the interaction between the SPI and TiO2-NM was via hydrogen bonds. Scanning electron microscopy and atomic force microscopy both showed that the microstructure of SPI-based films with TiO2-NM was compact. Moreover, as the content of TiO2-NM increased from 0 to 1.5 g/100 mL, the water vapor permeability and oxygen permeability were decreased from 5.43 to 4.62 g· mm/m2d· kPa and 0.470 to 0.110 g· cm−2· d−1, respectively. An increase from 6.67 MPa to 14.56 MPa in tensile strength and a decrease from 36.53% to 27.62% in elongation at break indicate the optimal mechanical properties of all groups. TiO2-NM films had excellent UV barrier properties, with a whiter surface with increasing TiO2-NM content. In addition, the SPI-based films with TiO2-NM showed antimicrobial activity, as evidenced by an inhibitory zone increasing from 0 to 27.34 mm. Therefore, TiO2-NM can be used as an antimicrobial agent in packaging films.