Shear-induced conformational changes and gelation of soy protein isolate suspensions

Abstract

Effects of high shearing (5 × 104 s-1) on the conformational change and shear-induced gelation of soy protein isolate suspension and the physico-chemical properties of the resultant gels were studied. The turbidity, viscosity and hydrophobicity were parameters used to monitor the conformational changes of soy protein isolate. The penetration strength and matrix structure were used to characterize the gel properties. The results showed that the turbidity, viscosity and hydrophobicity of 20 g/L soy protein isolate suspension or its supernatant increased with increasing shear time. Gel formed as 170 g/L soy protein isolate suspension was sheared at 50 °C and then cooled, or formed directly when it was sheared at 60 °C without cooling. The penetration strength of sheared suspension increased with increasing shear time. Scanning electron micrographs showed that a fibrous structure developed gradually from globular aggregates of soy protein isolate induced by shearing and elevated temperatures. © 1998 Academic Press Limited.