The mechanical behaviour of dough, gluten and starch was studied in an effort to
investigate whether bread dough can be treated as a two phase (starch and gluten)
composite material. Mechanical loading tests revealed rate dependent behaviour for
both the starch and gluten constituents of dough. There is evidence from Cryogenic
Scanning Electron Microscopy (Cryo-SEM) that damage in the form of debonding
between starch and gluten occurs when the sample is stretched. In addition, the Lodge
material model was found to deviate from the tension and shear stress-strain test data
by a considerably larger amount than from the compression test data. This could
indicate that ‘damage’ is dominant along the gluten-starch interface, causing
debonding; the latter occurs less under compression loading, but is more prevalent in
tension and shear loading. A single-particle finite element model was developed
using starch as a filler contained in a gluten matrix. The interface between starch and
gluten was modelled using cohesive zone elements with damage/debonding occurring
under opening/tension and sliding/shear modes. The numerical results are compared
to experimental stress-strain data obtained at various loading conditions. A
comparison of stress-strain curves obtained from 2D and 3D single-particle models
and a multi-particle model led to good agreement, indicating that the single-particle
model can be used to adequately represent the microstructure of the dough studied
here. Finally, the simulation of extrusion was performed using the finite element
method, where demonstration of the predictive capability of a continuum numerical
model with small scale experimental results was performed.