What Has Low-Intensity Ultrasound Informed Us about Wheat Flour Dough Rheology?1 The role of rheology in understanding the process behavior of dough and its predictive capacity with respect to breadmaking quality is of long-standing interest to cereal scientists. Over the past 12 years, we have undertaken a comprehensive examination of the rheology of wheat flour doughs using low-intensity ultrasound. Propagating shear waves at ultrasonic frequencies in conjunction with small-strain shear rheometry allowed us to show how a very broad distribution of relaxation times is necessary to define the complex shear modulus of wheat flour dough. When propagating longitudinal ultrasonic waves, three distinct regions are seen in the ultrasonic spectrum arising from the presence of bubbles in the dough. At low frequencies, where the properties of the bubbles–dough matrix “composite” are probed, the rheology of air-mixed doughs contrasts markedly with that of doughs mixed under vacuum. Therefore, all dough rheology is affected by the bubbles within the dough. |