Flour Quality effects on percolation of gas bubbles in wheat flour doughs

To investigate how flour affects crumb structures, we used Synchrotron X-ray tomography to scan and capture the growth of gas bubbles in leavened and unleavened bread doughs of two different flours. Bubbles were mobile in all doughs; they coalesced and disproportionated with the rate of coalescence being higher in leavened doughs. In unleavened dough, new bubbles were detected, attributed to arise from poro-visco-elastic relaxation of gluten as dough rested. In each yeasted dough, a single, massively inter-connected cluster formed which percolated at ~26% dough porosity irrespective of flour type in dough. Following percolation, dough expansion was driven primarily by growth of the percolating bubble. Between flours, the rate of coalescence was higher in Wylkatchem (Wylk), an Australian flour dough, than in Canadian Western Red Spring (CWRS) flour dough, known for superior proof and bake qualities. How the physical and rheological properties of dough liquors could have affected the stabilities of bubbles in these doughs have been discussed.