John Mitchell, Biopolymer Solutions Ltd

The hydrocolloid xanthan gum is modified by extrusion processing. The modified material behaves as a polyelectrolyte particle showing excellent dispersibility in water and   a strong salt dependence of the dispersion viscosity.  Comparison of the temperature dependence of the viscosity with the temperature of the order/disorder transition measure by differential scanning calorimetry suggests that the particulate structure is maintained by dihelical associates which rearrange during the extrusion process.  At salt levels appropriate to many food products the disruption of the particles on heating can result in a similar viscosity profile to that observed during the pasting of starch.  The potential for physically modified xanthan as a low calorie, soluble dietary fibre, replacement for starch is discussed.

Emailjohn.mitchell@nottingham.ac.uk