Effect of sesbania gum on the rheological, textural, and microstructural characteristics of CaSO4-induced soy protein isolate gels

This study evaluated the rheological, textural, and microstructural characteristics of CaSO4-induced soy protein isolate (SPI) gels in the presence of various sesbania gum (SG) concentrations. The results showed that SG significantly increased the storage modulus (G′), loss modulus (G″), and mechanical strength, especially, in adding 0.3 wt% SG. Furthermore, the gel microstructures varied from homogenous to slight phase separation with a continuous protein phase followed by significant phase separation, depending on SG concentration. The fractal dimension of the gels calculated from confocal laser scanning microscopy (CLSM) images decreased gradually with increased SG concentrations. The denser microstructure in the local regions is related to improving the water-holding capacity (WHC). Fourier transform infrared spectroscopy (FTIR) spectra confirmed that hydrogen bonds are crucial in maintaining the three-dimensional network structure of the SPI-SG gels. A lower concentration (0.1–0.3 wt%) of SG facilitates the formation of the gel; however, if the concentration of SG becomes 0.4 wt% or 0.5 wt%, SPI-SG interactions are inhibited by the entangled galactomannan chains, resulting in significant phase separation. Our findings suggested the great potential of SG in modulating the properties and structure of CaSO4-induced SPI gels, obtaining novel SPI-based food gel products with improved texture.