EFFECTS OF MICROFLUIDIZATION ON THE FUNCTIONAL-PROPERTIES OF XANTHAN GUM

The effects of microfluidization on xanthan gum were studied by flow b ehaviour, hydration rate, water uptake and molecular weight determinat ions. The effect of pressure and number of passes on the xanthan solut ion produced a decrease in all these functional properties. Consequent ly the thickening and, stabilizing properties were reduced. We argued that the high shear, turbulence forces and cavitation involved in the microfluidization process produced ordered-disordered conformational t ransition (by opening of the molecule) and polymer degradation. The op ening of the molecule occurred first, followed by polymer degradation due to mechanical stress. Differences observed in viscosity between tr eated xanthan dispersion and their spray-dried powders is associated w ith reorganisation of xanthan aggregates during heating and cooling, w hich occurred in spray-drying, but these phenomena do not change the h igh pressure effect on the biopolymer. (C) 1998 Published by Elsevier Science Ltd. All rights reserved.