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Ultrasonic Characterization of Unyeasted Bread Dough of Different Sodium Chloride Concentrations

¹Department of Food Science, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2. ²Department of Physics and Astronomy, University of Manitoba, Winnipeg, Manitoba, Canada R3T 2N2. ³Corresponding author. E-mail: martin.scanlon@ad.umanitoba.ca

Altering the properties of dough by reducing sodium chloride (NaCl) content affects aeration processes during mixing. The effect of NaCl concentration on the bubble size distribution (BSD) in unyeasted doughs was investigated by an ultrasonic transmission technique through analysis of frequency-dependent ultrasonic phase velocity and attenuation coefficient. As NaCl concentration was decreased, the volume fraction of gas in the dough increased, resulting in a larger attenuation coefficient for the dough. From the peak in attenuation coefficient, estimates of the median radius and the width of the lognormal BSD in the dough were extracted, both of which were sensitive to the dough's NaCl concentration. As NaCl concentration was reduced, the bubble radius decreased and the width of the distribution increased, in accordance with expectations arising from changes in the dough's consistency. Over the course of 150 min, the radius increased (40–50%) and the width decreased (4–8%) for all dough formulations, consistent with changes in the BSD arising from disproportionation. These dynamic changes demonstrate that dough is an interesting soft material whose formulation can be manipulated to enable it to possess different BSDs; the diffusively driven evolution in these bubble sizes can be investigated noninvasively with ultrasound.