Cereal Chem 52:154r - 169r.  |  VIEW ARTICLE
Rheological and Thermodynamic Properties of Gluten Gel.

C. B. Funt Bar-David and C. H. Lerchenthal. Copyright 1975 by the American Association of Cereal Chemists, Inc. 

When specimens of wheat gluten gel were stretched under constant stress to small extensions (epsilon t- less than 1), the recovery following release of load was complete and mainly immediate, while the apparent modulus of immediate recovery was low and constant, similar to rubber elasticity. Beyond a certain extension, however, the recovery was no longer complete; the residual deformation was attributed to viscous flow; then, the apparent moduli of immediate and delayed recovery increased with the stress preceding recovery and the coefficient of apparent viscosity decreased with stress. Part of the energy of recovery or the conserved energy (Wie) was dissipated during sustained loading at a time-dependent rate. An increase of loading time from 5 sec to 5 min caused an energy decay at a ratio of 25:1. Since the material changed during the experiment from a linear viscoelastic solid (full recovery) to a nonlinear elasticoviscous liquid (flow and full stress relaxation) it is proposed to call it rheologically unstable. This instability is described by a rheological model based on a modified Kelvin body in series with a Hooke body. The modification consists in a Newton element bridged by a shear pin, in series with the Hookean element of the Kelvin body, the shear pin accounting for the solid-liquid transition beyond a yield point.