Effect of LBG on the gel properties of acid-induced SPI gels

- LBG significantly changes the rheological and microstructural properties of SPI gel.
- Creep/recovery rate and elasticity increases with LBG addition.
- SPI-LBG gel shows a typical Type I network behavior in LAOS test.
- LBG addition lowered the strain amplitude at which the non-linear behavior occurs.
- Presence of LBG increased the volume of pore between protein networks.

The effect of the addition of locust bean gum (LBG) on the rheological properties, microstructure and fractal dimension of glycono-δ-lactone induced soy protein isolate (SPI) gels were studied (LBG concentration = 0.01%-0.04%, SPI concentration = 6%). Both the small and large amplitude oscillatory shear measurements were carried out to characterize the rheological properties of SPI and SPI-LBG gels. The G′ of SPI-LBG gels was highly frequency dependent within the frequency range of 6.28 rad/s to 62.8 rad/s. Fourier transform rheology was used to analyze the higher harmonic signals from nonlinear stress waveform. SPI-LBG gels showed typical Type I network behavior similar to that of SPI gel at strain amplitude >2% in LAOS tests. Creep/recovery tests showed that the addition of LBG increased both the elastic and viscous moduli of SPI-LBG gels. The image of the microstructure captured by confocal laser scanning microscopic (CLSM) was used to determine the fractal dimension. The protein network structure of SPI-LBG gels showed greatly bigger pore volume, better scale behavior than SPI gels, and the chaos and complexity of the protein aggregates in SPI-LBG gels were much less than that in SPI gel. LBG was found to play an important role in a SPI-LBG gel system.