Aeration during bread dough mixing: II. A population balance model of aeration

A novel model for the aeration of dough during mixing is presented. A population balance model was used to model bubble entrainment, break-up and disentrainment over the whole duration of a mix. Following a series of simplifying assumptions, including that all bubbles are entrained with the same volume, the model parameters were fitted to original and previously published experimental dough voidage profiles over the duration of a mix involving a pressure step-change. The assumption that no bubble break-up occurred during mixing enabled a simple model to be derived which quantitatively represented the experimental data, for both a pressure step-up and down midway through mixing, with two mixing parameters: The volumetric entrainment rate and the disentrainment coefficient. Assuming that instantaneous bubble break-up occurred enabled a model to be derived which, with the same two parameters, could qualitatively represent experimental bubble number densities calculated through measurements of dough bubble size distributions. © 2004 Institution of Chemical Engineers.