A hypothesis for the structure and rheology of glutenin

Abstract

AbstractIt is suggested that because of the rapid lowering of the viscosity of its solutions by reducing agents the major, important fraction of glutenin consists of linear molecules made up of polypeptide chains linked to one another difunctionally by S.S bonds. When dough is stretched the natural tendency of the polypeptide chains to return to a contracted state of low free energy accounts for the elasticity. The interchain S.S bonds are essential for elasticity because inter‐chain adhesion between individual polypeptide chains will not overcome the stronger intra‐chain forces unless reinforced by the S.S bond. If extension exceeds the elastic limit, viscous flow occurs because steric hindrance and molecular slip will prevent a return to the original conformation. Disulphide interchange is believed to play an important part in stress relaxation. Mechanical scission of S.S probably occurs when molecules at their elastic limit are subjected to too much stress; this may explain the work maximum in the Chorleywood Bread Process. Explanations are advanced for mechanical and activated dough development and evidence in favour of the hypothesis is discussed.