Characterization of wheat flour-water doughs.: Part I:: Rheometry and microstructure

The results presented in this paper concern doughs prepared from an industrial soft wheat hour mixed with water using the traditional Brabender farinograph. These doughs are characterized using dynamic rheometrical measurements. In parallel, an innovative microscopy study, the Environmental Scanning Electron Microscope (ESEM) is investigated and found to be very well-suited for the observation of such doughs. A change in the slope of the curve giving the maximum of consistency is observed at a typical water content, due to the presence of excess free water. The main rheometrical characteristics \eta*\ and tan delta are exhibited for this kind of dough. Their adequacy to differentiate between various doughs is emphasized. Parameters such as mixing time, water content and rest time are shown to influence both the rheometrical properties and the microscopic structure of doughs. Changes generated by mixing are interpreted at the molecular level. It is shown that the study of the microstructure is essential to compare the evolution of different doughs. (C) 1999 Elsevier Science Ltd. All rights reserved.