EXTRUDATES OF STARCH XANTHAN GUM MIXTURES AS AFFECTED BY CHEMICAL-AGENTS AND IRRADIATION

Mixtures of starch, xanthan gum and either polyvinyl alcohol, epichlor ohydrin, valeric acid or adipoyl chloride were extruded. Properties of extrudates including apparent viscosity, water solubility, water abso rption indices and exrudate expansion were measured for different prop ortions of xanthan gum, 70% amylose starch (with or without irradiatio n) and chemical agents. Extrusion with chemical agents and irradiation changed physical properties of both starch and xanthan gum. Expansion s of extrudates were higher than that of starch. Viscosity of extrudat es increased with xanthan gum concentration. The addition of 1% (w/w) polyvinyl alcohol had the greatest effect of the chemical agents. Irra diation increased the apparent viscosity of starch-xanthan gum mixture s.