A parametric and microstructural study of the formation of gluten network in mixed flour–water batter

Abstract

The mechanism of gluten network development is still unclear and remains difficult to study since gluten network formation in bread dough is a rather quick process. In order to better characterize this dynamic event, we slowed down its kinetics by increasing the dough water content. During mixing, performed with a planetary mixer at variable mixing speeds and flour/water ratios, the torque was recorded. Common flours from wheat cultivars Orvantis, Caphorn and Isengrain, similar in composition and Farinograph parameters, were studied. At low flour/water ratios, mixing curves showed a lag phase preceding the increase of torque to the maximum dough resistance peak. Lag phase duration increased with dough water content, whereas increasing the mixing speed decreased time for optimal dough development. For the three flours studied, the time for optimal dough development was found to be related to the instantaneous power delivered to the dough during the lag phase and not to the specific mechanical energy required to get the maximum torque. Besides the effect of this common control parameter, flours exhibited wide variations in response to a given instantaneous power delivery, with dough development times varying by a factor of 6. Orvantis was always faster to develop than Caphorn or Isengrain. Optical microscopy observations of batters, using a protein stain, showed that gluten network development resulted from two successive phenomena. The first one involved the formation of microscopic gluten lumps, and the second one consisted of the development of gluten strands starting at the end of the lag phase. The very different behaviours observed for the three flours are discussed in relation to the batter structure and to the colloidal properties of gluten proteins.