Energetical and rheological approaches of wheat flour dough mixing with a spiral mixer
Résumé
Wheat flour dough was mixed in a spiral mixer for different operating conditions, at a speed ranging from 80 to 320 rpm, for a period of 7-15 min. The specific mechanical energy E, delivered and the dough temperature T-d were continuously recorded and varied from 7 to 82 kJ/kg and T-d of 13.5 to 36 degrees C, respectively. E-s and T-d were strongly correlated because of viscous dissipation but variations of ingredients initial temperature allowed to uncouple them. The energy balance during mixing process was set through a simple model assuming constant heat transfer (h = 75 W/(m(2) degrees C)) which took into account thermal losses. Shear viscosity curves of the dough were determined by correlating volumic power to angular speed; by comparison to typical dough shear flow curve, a constant characteristic of the mixer geometry (K-s = 1.55) was determined like for models of mixer power consumption. The impact of mixing on small deformation rheological properties was assessed by DMA and the variations of the ratio, of maximum (75 degrees C) to minimum (50 degrees C) elastic modulus, was interpreted in relation with gluten network development. (C) 2011 Elsevier Ltd. All rights reserved.