Rheological behaviour of blood orange juice concentrated by osmotic distillation and thermal evaporation

Fruit juices concentrated by osmotic distillation are characterized by higher organoleptic and sensorial properties than those of juices concentrated by thermal evaporation as confirmed by several research studies. On the other hand, no literature is readily available about the rheological characterization of juices concentrated by osmotic distillation. This work aimed at investigate the rheological behavior of the concentrated blood orange juice prepared from the clarified juice by using thermal evaporation and osmotic distillation processes as a function of solids concentration in the range 115 - 614 g/kg of total soluble solids (TSS) within a range of 20 - 70°C. The effect of the temperature and concentration on the juice viscosity was studied. Arrhenius-type correlation equations for viscosity were used to represent the temperature dependence of viscosity. Values of the Arrhenius equation parameters (flow activation energy) were calculated for the measured viscosities of juices as a function of concentration. Results indicated no significant differences in the rheological behavior for orange juices concentrated with both methods. The juices exhibited a Newtonian behavior regardless of the concentration method.