Bread dough rheology and recoil I. Rheology

A new set of experiments on a bread dough includes small-strain oscillatory behaviour, larger-strain oscillatory behaviour, simple shearing beginning from rest, uniaxial elongation beginning from rest, relaxation after sudden shear and recoil from elongation. We believe this is the most complete set of rheological data yet reported for a bread dough. Analysis of these soft-solid experiments proceeds from a Lodge-type rubberlike material with a power-law memory function. The model suggests that the response to steady shear and elongational flows may be described as a product of (strain rate)(P) times a function of strain; the exponent p is found to be about 0.2-0.3 from small-strain oscillatory measurements. Experiments confirm this finding. The model overestimates stresses, and in order to improve predictions, the use of a KBKZ model and a damage function model are investigated. Due to the eventual fracture of the soft-solid material, the idea of a damage function was adopted to produce a simple accurate, integral-type constitutive model for small-strain oscillations, simple shearing and elongation. Further analysis of reversing strains, for example, larger-strain oscillatory flows and recoil, is needed. (c) 2007 Elsevier B.V. All rights reserved.