Comparing compression and biaxial tests for bread dough

Due to the potentially anisotropic microstructure of bread dough, the pre-test deformation produced during the making of the specimens significantly affects the rheological properties of dough, and the resistance to deformation is increased. Some new experimental results for JANZ dough are reported in this paper. Lubricated compression tests have been made up to medium-size (order 1) Hencky strains, and we find that the stress response given by the compression test is consistent with the one given by the spherical bubble test if pre-strain is taken into account. Therefore a damage function model can be successfully used to describe the rheological behaviour of the dough for elongation, compression and biaxial stretching. The Mooney–Rivlin term in the model is very important for the biaxial stretching, but not for elongation and shear. The damage function used in compression is the same as that used in elongation and shear, when computed using the maximum positive Hencky strain in all cases. Thus the deformation mode does not make the damage function change; it depends only on the dough variety. Good agreement between the experimental data and the predictions given by the model is observed.