Crust density in bread baking: Mathematical modelling and numerical solutions

A model for the formation of a “crust” during bread baking is presented. The crust is the outermost part of the loaf where the final bread density is significantly higher than in the “crumb”, the interior of the loaf. The model is based on a collapse mechanism, whereby raised pressures due to thermal expansion and water evaporation squash bubbles in the bread as the dough sets and fractures; the latter process allows vapour within bubbles to escape.A preliminary analysis of some aspects of the model and an indication of the numerical solution are also presented. Fuller results and their implications for bread manufacture will be given in a second paper.