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Influence of Shaping and Orientation of Structures on Rheological Properties of Wheat Flour Dough Measured in Dynamic Shear and in Biaxial Extension

¹Chaire de Biochimie Industrielle Agro Alimentaire, UMR SCALE 1211, Conservatoire National des Arts et Métiers, 292 rue Saint-Martin, 75141 Paris Cedex 3, France. ²Biophysics of Food Materials, Food Science Departement, UMR SCALE 1211, AgroParisTech, site de Massy, 1 Avenue des Olympiades, 91 744 Massy Cedex, France. ³Corresponding author. Phone: 33.1.69.93.51.27. Fax: 33.1.69.93.50.05. E-mail: Camille.michon@agroparistech.fr

Characterization of the rheological properties of wheat flour dough during mixing and baking without modifying its structure or mechanical properties is not easy. In this work, the effect of dough setting pre-orientation and strain orientation during characterization are assessed for differently structured wheat flour doughs (various water contents and addition of glucose oxydase). Rheological properties were measured in dynamic shear as rotational (CSL²100 fitted with a cone-plate geometry) or radial (CP20 fitted with a plate-plate geometry) small deformation mode and in lubricated squeezing flow and relaxation called large deformation mode. In comparison with radial shearing, rotational shearing induces a much larger preorientation of the network and thus a strain-hardening phenomenon that affects the rheological measurements (storage modulus is overestimated) but relaxes, at least partially, during a rest period. Consequently, a longer period of time has to be allotted (allowing stress relaxation) before starting measurements. Plate-plate geometry induces less preorientation and allows measurement a few minutes after setting. However, it has less discrimination of the differently structured dough than the cone-plate geometry used in rotational mode. Results which partially agree with those of the CP20 are obtained using the lubricated squeezing flow followed by stress relaxation.