A suspension model of the linear viscoelasticity of gluten doughs

We regard gluten dough as a mixture of gluten, starch and water. We show that stress intensification around the starch particles enables one to describe the rapid strain softening of dough at low strains. The starch is in the form of a combination of A-particles (close to oblate spheroids) and B-particles (almost spherical). This suggests that a suspension theory should be able to account for the linear viscoelastic properties of doughs. We develop a new representation for the prediction of the linear viscoelastic properties of a viscoelastic matrix (gluten) with embedded oblate spheroids and spherical particles. The calculations are compared with experiments on gluten mixes derived from an Australian Baker’s flour. We note that the non-sphericity of the A-particles is very important in stiffening the gluten matrix and also that the effective volume fraction of the starch is greater than that calculated by assuming a starch density of 1.4 g/ml.

► In gluten doughs we show that the rapid softening seen at small strains is due to stress intensification around the starch particles.
► A new suspension theory enables us to account for the behaviour in the linear viscoelastic region, but it is essential to factor into the calculation the two kinds of starch particles (A (oblate spheroids) and B (spheres)).
► Calculations are compared with experiments on gluten mixes derived from an Australian Baker's flour with reasonably good agreement.