Using an in-line rotating torque transducer to study the rheological aspects of malaxed olive paste

• A torque transducer was used to read in real time the torque value in a malaxer.
• Torque and rotational speed allow to predict mean viscosity values.
• The model gave good predictions of the experimentally measured apparent viscosity.
• Torque measurement allow to determine right malaxation process interruption time.

A torque monitoring system was implemented on a malaxer machine prototype to investigate the rheological parameters of olive paste. In this study, the correlations between torque values and apparent viscosities were studied. The torque – viscosity correlation is important for defining an in-line parameter that can directly monitor during the kneading process, to determine when the paste is ready to progress to the next phase, to optimise the process, and to achieve higher quality products. During the malaxation process, the torque on the reel was measured using a rotating torque transducer. Viscosity measurements were performed using a Brookfield rotational viscosimeter. A model that correlates torque with the viscosity coefficient and flow behaviour index was defined. The good correlation between the off-line viscosity measurements and viscosity, as calculated by the model, confirms that the predicted mathematical model is able to produce a reliable assessment of the viscosity and that the torquemeter may represent an efficient device to obtain quite accurate on-line viscosity measurements.