Ultrasonic Characterization of Unyeasted Bread Dough of Different Sodium Chloride Concentrations

Abstract

Cereal Chem. 91(4):327-332Altering 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 sensi-tive 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.

Relation between ultrasonic properties, rheology and baking quality for bread doughs of widely differing formulation

“…The frequency‐dependent changes in both phase velocity and attenuation coefficient are very similar to those reported for strong breadmaking flours analysed by transmission experiments . The peak in attenuation coefficient, which occurs between 1 and 2 MHz for D, E and F, is indicative of a low‐frequency resonance arising from the bubbles entrained into the dough during mixing .…”

“…The frequency-dependent changes in both phase velocity and attenuation coefficient are very similar to those reported for strong breadmaking flours analysed by transmission experiments. 26,47 The peak in attenuation coefficient, which occurs between 1 and 2 MHz for D, E and F, is indicative of a low-frequency resonance arising from the bubbles entrained into the dough during mixing. 17,26 On the low-frequency side of the peak, velocity and attenuation are lower, indicative of the long-wavelength probing of an effective medium of matrix and bubbles that constitute the dough.…”

The entrainment and evolution of gas bubbles in bread dough—A review

“…Increased salt (NaCl) content in the dough has been observed to increase dough density at the end of mixing (Chin, Campbell et al, 2005; Koksel et al, 2014), indicating that increased salt decreases the volume of gas bubbles entrained into the dough during mixing. The negative effect of increased salt content on gas bubble entrainment is attributed to NaCl‐induced changes in the protein network (Beck et al, 2012).…”

“…Dough density was also observed to increase with increasing water content in the dough (Koksel & Scanlon, 2012), indicating that higher water content doughs had a lower volume of gas bubbles entrained during mixing (Peighambardoust et al, 2010). In terms of VF measurements, salt (NaCl) reduction leads to a higher volume of gas bubbles entrained into the dough (Bellido et al, 2006; Koksel et al, 2014).…”

“…When the mixing development time of dough is fixed (as opposed to mixing until optimal development), higher salt content doughs are relatively less developed, resulting in a lower volume of gas bubbles entrained (Koksel & Scanlon, 2012). An ultrasonic transmission technique has been used to measure BSDs in nonyeasted doughs varying in formulation, and the BSDs have been fitted with a lognormal distribution (Koksel et al, 2014;Leroy et al, 2008). The evolution of BSD was investigated by measuring the median bubble size and the width of a lognormal distribution function fitted to the BSD (Koksel et al, 2014;Leroy et al, 2008).…”