Optimization of high-pressure-assisted xanthan gum dispersions for the maximization of rheological moduli: Application of time-pressure/ temperature superposition principle.

The influence of high-pressure (HP) treatment (300–600 MPa) on the rheological behavior of xanthan gum (XG) dispersions was studied at ambient temperature. The pressure-treated samples were thereafter isothermally heated in situ in a rheometer to include the thermal effect on the oscillatory rheology. The main objective of this work was to study the influence of three independent variables, namely concentration (0.75, 1 and 1.25%), pressure (0.1, 300 and 600 MPa), and temperature (40, 55 and 70 °C) on the maximization of the oscillatory rheological moduli (G′, G″ and η*) of xanthan gum using central composite design (CCD) method. The developed quadratic regression model indicated that all the linear, two quadratics (concentration and temperature), and two interactions (concentration-pressure and concentration-temperature) terms were significant (P < 0.05) for oscillatory moduli (R 2 = 0.99) and insignificant lack-of-fit. The mechanical rigidity produced by the pressure was higher than the thermally treated xanthan, which needs further in-depth structural analysis to confirm the pressure-assisted order-disorder transition. Both the time-pressure and time-temperature superposition principles were fitted well for the HP-treated xanthan dispersions. [Display omitted] • Rheology of High-pressure-treated xanthan gum were investigated using RSM design. • The concentration and temperature influenced the oscillatory moduli significantly. • Pressure-temperature resulted in a higher rigidity than the thermally-treated dispersions. • The pressure assisted higher moduli could be associated with the order-disorder transition. • The superposition principle fitted well for both the pressure and temperature with frequency. [ABSTRACT FROM AUTHOR]