Effect of high-hydrostatic pressure and concentration on rheological characteristics of xanthan gum

The individual and interactive effects of pressure (80–400 MPa) and concentration (0.25–1.25%) of xanthan gum on rheological characteristics were studied by the application of the response surface methodology using a controlled stress rheometer. Pressurized xanthan gum exhibited pseudoplasticity with yield stress and flow was adequately described by Herschel-Bulkley model. Slight structural degradation was found between upward and downward curves of pressurized xanthan gum. A quadratic model developed for rheological parameters met all the criteria of good fit and provided useful information. It was observed that pressure and concentration individually affected consistency coefficient (P<0.05), while there was no effect of pressure on flow behavior index and yield stress (P>0.05) of xanthan gum. The concentration of gum and pressure level individually and in combination significantly (P<0.05) affected apparent viscosity at shear rate of 250 s−1. The concentration was the most effective factor and pressure was the least.