Durum wheat dough torque measurements: characterization and study of the mixing process parameters as a function of water and salt amounts

Different physicochemical phenomena are involved in breadmaking, which produce perceptible changes in the rheological properties of dough. In this regard, the kneading phase is crucial for the assessment of the quality of the final product. Indeed, the determination of the optimal time in the mixing process allows to optimize the rheological properties of the dough and the energy consumption. In this work, torque measurements were carried out on durum wheat commercial semolina using a Brabender Mixer 350 (Brabender® GmbH, Duisburg, D) where semolina was mixed with water in different amounts (from 40% to 60% of semolina weight). Each sample was mixed for 20 minutes. The salt effect was instead investigated by adding a variable amount of salt (from 0% to 2.5% of semolina weight). The optimal mixing time value, which occurs at the maximum torque value, was determined and studied with respect to salt and water quantity. Additionally, spectrograms of the torque time series data were computed in order to provide the magnitude (and frequency) of the torque oscillations with time. The results showed a significant influence of water amount on the torque maximum value and on the mixing time, with the latter that linearly depends on water amount. Also, the amplitude oscillations resulted to be related to the water amount, as their amplitude decreases when the water amount increases. On the other hand, the salt effect is less evident but an influence on optimal mixing time is however detected.