Proving of bread dough I - Modelling the evolution of the bubble size distribution

Models for the growth of bubbles are reviewed. A model of the growth of bubbles during proving of bread dough is then presented, based on diffusive mass transfer of carbon dioxide gas into a population of bubbles. The model incorporates the rate of gas production by yeast and the bubble size distribution, and is solved to simulate the dynamic growth of these bubbles. The effects of the number and size of bubbles and the proving temperature and yeast concentration on the growth of the dough piece are simulated. A greater number of bubbles in the dough, which would be achieved by mixing at higher pressures, results in an initially more rapid transfer of gas into the bubbles. Consequently there is a slower increase in carbon dioxide concentration in the liquid dough phase, such that later during proving the rate of bubble growth slows. Increasing yeast level increases the rate of gas production and hence the growth of the dough piece. Increasing temperature similarly increases the rate of growth of bubbles, partly due to the increased rate of gas production, but also as a result of the decreased gas solubility at higher temperatures.