The effect of glucono-δ-lactone on the gelation time of soybean 11S protein: concentration dependence

Abstract

Gelation kinetics of soybean 11S protein by glucono-δ-lactone (GDL) was investigated by dynamic viscoelastic measurements. The gelation time decreased with increasing GDL concentration at a constant 11S concentration (4%). The mechanical loss tangent at the final stage of the gelation decreased with increasing protein concentration, but was independent of the GDL concentration. The gelation time of systems which consist of 11S and GDL at a fixed ratio decreased with increasing 11S concentration. However, the time at which the gelation curve reached saturation did not decrease so much with increasing GDL concentration at higher concentrations of the protein. It was found that the decrease of pH by addition of GDL greatly contributes to the gelation time. The relationship between the gelation time and 11S concentration at low concentrations suggested that the minimum 11S concentration for gelation is 1.03% and the junction zones of the systems are formed by 2.6 single polymer chains.