Radiation induced degradation of xanthan gum in the solid state

• Radiation-induced degradation of xanthan gum (XG) described.
• The influences of dose rate on the radiation degradation of XG were examined.
• G(S) and degradation rate of XG were calculated by using molecular weights data.

In this study, the effect of ionizing radiation on xanthan gum was investigated. Xanthan samples were irradiated with gamma rays in air at ambient temperature in the solid state at different dose rates and doses. Change in their molecular weights was followed by size exclusion chromatography (SEC). Chain scission yield (G(S)), and degradation rate constants (k) were calculated. The calculated G(S) values are 0.0151±0.0015, 0.0144±0.0020, 0.0098±0.0010 µmol/J and k values are 1.4×10−8±1.4×10−9, 1.3×10−8±2.0×10−9, 8.7×10−9±1.0×10−9 Gy−1 for 0.1, 3.3 and 7.0 kGy/h dose rates, respectively. It was observed that the dose rate was an important factor controlling the G(S) and degradation rate of xanthan gum.Considering its use in food industry, the effect of irradiation on rheological properties of xanthan gum solutions was also investigated and flow model parameters were determined for all dose rates and doses. Rheological analysis showed that xanthan solution showed non-Newtonian shear thinning behaviour and ionizing radiation does not change the non-Newtonian and shear thinning flow behaviour of xanthan gum solutions in concentration ranges of this work. It was determined that, Power Law model well described the flow behaviour of unirradiated and irradiated xanthan solutions.