Effects of mixing speed and work input on dough development and aeration.

Mixing of the dough is the critical control point in the breadmaking process. Mixing aerates the dough and develops its rheology such that inflation and coalescence of the bubbles proceed in the correct fashion so as to create the desired bread structure and texture. The amount and rate of energy imparted to the dough during mixing affects both aeration and rheology, but these two facets of dough mixing have seldom been studied together. This paper investigates the effects of mixer speed and work input in a Tweedy-type mixer on the aeration of the dough and its rheology, using dough density measurements and bubble inflation rheometry. Increasing mixing speed had little effect on the gas-free dough density, but increased the void fraction of gas occluded in doughs made from either strong or weak flour. As mixing progressed, the air content tended to increase over the range of work inputs tested. For both flours, the strain hardening index, failure strain and failure stress increased with work input initially, followed by a decrease. The absolute values were all higher for the strong flour, while maximum values and the work input at which the maximum occurred depended on the mixing speed. These results demonstrate how both aeration and rheological characteristics of dough depend on both the total work input and the work input rate.