Résumé
This work studies the role of dispersing and dispersed phases in the rheological properties of fruit juices during concentration operations. A special focus was given to the behavior of the dispersed phase (SS) when it is concentrated singly or simultaneously with the dispersing phase (TSS). The experimental strategy consisted in the characterization of the viscoelastic properties and the flow behavior of various orange juice suspensions containing different concentrations of soluble and suspended insoluble compounds. Results showed that the presence of solutes in the dispersing phase increases the cohesion energies between the particles of the dispersed phase and governs their viscoelastic behavior. As for the flow behavior, the concentration of dispersed particles proved to be the parameter controlling the consistency indexes in the TSS domain between 0% and 30%. Furthermore, results reveal a TSS threshold around 40%, at which great physical alterations may occur to the dispersed phase. This study provides new knowledge concerning the distinctive role of the dispersing and the dispersed phases in the viscoelastic properties and flow behavior of fruit juices. This information could be useful to predict and control the rheological behavior of fruit juices during concentration operations such as vacuum concentration and microfiltration.