Rheological Properties of Dough During Mechanical Dough Development

Abstract

During mechanical development dough is subjected to both shear and extensional deformations. Thus, it is expected that both flow conditions contribute to the development of dough. In order to monitor rheological changes, occurring during mixing, shear and extensional properties of dough prepared with two flours of different strength and various levels of mixing energy were determined using fundamental rheological methods. Rheological measurements included: small deformation and large deformation (shear test), planar extensional flow and a combined shear/extensional flow test, namely extrusion test. Results obtained in this research showed that, during mixing, dough develops with an increase in both apparent shear and extensional viscosities. For all the tests, plots of the measured rheological properties as a function of the mixing energy resembled typical mixing curves. This indicated that the increase in the power drawn by the mixer motor is due to the increase in both apparent shear and extensional viscosities. After peak dough development these properties decreased synchronously with the mixing curves. Results from small deformation shear tests exhibited large variability, particularly when non-mixed and underdeveloped doughs were tested. This variability was associated with poor water distribution in the sample due to insufficient mixing. Results of large deformation tests, including shear, planar extensional flow and the extrusion test, were less variable and showed that mixing and type of flour affect the rheological properties of dough.