Preparation and characterization of antioxidant soy protein isolate films incorporating licorice residue extract

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

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.

Characterization of Soybean Protein Adhesives Modified by Xanthan Gum

The aim of this study was to provide a basis for the preparation of medical adhesives from soybean protein sources. Soybean protein (SP) adhesives mixed with different concentrations of xanthan gum (XG) were prepared. Their adhesive features were evaluated by physicochemical parameters and an in vitro bone adhesion assay. The results showed that the maximal adhesion strength was achieved in 5% SP adhesive with 0.5% XG addition, which was 2.6-fold higher than the SP alone. The addition of XG significantly increased the hydrogen bond and viscosity, as well as increased the β-sheet content but decreased the α-helix content in the second structure of protein. X-ray diffraction data showed significant interactions between SP molecules and XG. Scanning electron microscopy observations showed that the surface of SP adhesive modified by XG was more viscous and compact, which were favorable for the adhesion between the adhesive and bone. In summary, XG modification caused an increase in the hydrogen bonding and zero-shear viscosity of SP adhesives, leading to a significant increase in the bond strength of SP adhesives onto porcine bones.

Preparation and characterization of soy protein isolate-collagen self-assembled nanomicelles

This paper describes the preparation and characterization of soy protein isolate (SPI)-collagen self-assembled nanomicelles. Novel SPI-collagen self-assembled nanomicelles via hydrogen bonding and electrostatic interactions were developed. SPI-collagen soluble complexes were formed at pH 6.4, which was lower than the isoelectric point of collagen (pI = 7.8) and higher than that of SPI (pI = 4.5). This research mainly focuses on the intermolecular force between the SPI and collagen. The diameter distribution, critical association concentration, and stability of the SPI-collagen self-assembled nanomicelles were investigated in this research. It was found that the SPI and collagen had hydrogen bonding and electrostatic interactions, and then formed natural complex nanomicelles in a weakly acidic environment. The preparation of SPI-collagen self-assembled nanomicelles was performed in an aqueous environment without surfactants or toxic agents. As a fixing agent, transglutaminase (TGase) promoted the intra- and intermolecular cross-linking of the nanomicelles, which improved the stability of the self-assembled nanomicelles. The SPI-collagen nanomicelles had a good stability. This research may provide a reference for the utilization of SPI-collagen self-assembled nanomicelles.

This paper describes the preparation and characterization of soy protein isolate (SPI)-collagen self-assembled nanomicelles.