2013 Volume 19 Issue 1 Pages 51-57
The role of disulfide bonding in the structure of gels formed from soybean proteins was investigated. Heat-induced gels of 11S globulin (11S) and soybean protein isolate (SPI) were prepared using magnesium chloride as a coagulant, and the effects of 2-mercaptoethanol (2-ME), which prevents the formation of disulfide bonds, on the viscoelastic properties and microstructures of these gels were determined. The effects of 2-ME were quantified using dynamic viscoelastic measurement (DVM) and confocal laser scanning microscopy (CLSM). DVM indicated that 11S gels showed higher storage modulus (G’) and lower mechanical loss tangent (tan δ) than SPI gels. CLSM was used to examine microstructures of 11S and SPI gels, and to determine their fractal dimension and the average density of network structures. The 11S gels showed lower fractal dimension and denser gel networks than SPI gels. These characteristic viscoelastic properties and microstructures of the 11S gel were lost with increasing 2-ME concentration, suggesting that the characteristic properties of 11S gels are due to disulfide bonding.
