Rheological characteristics of inulin solution at low concentrations: Effect of temperature and solid content.

The rheological properties of inulin solution was investigated at different solid content (Xs) ranging from 1 to 12 % at wide range of temperatures ranging from 10 to 85 °C. The rheological parameter shear stress was measured upto a shear rate of 300 s(-1) using concentric cylinders attachment by controlled stress rheometer. The investigation showed that the inulin solution behaved like Newtonian liquid and viscosity (η) was in the range 2.0998 to 3.2439 mPa s depending upon the concentration and temperature studied. The temperature dependency of Newtonian viscosity of inulin solution was described by Arrhenius equation (r > 0.88, p < 0.05) and activation energy (Ea) for viscous flow was in the range 2.111 to 3.013 kJ/mol depending upon the solid content studied. The flow activation energy (Ea) of inulin solution was significantly (p < 0.05) affected by solid content and described by exponential type equation (r = 0.9646, rmse% = 1.07, p < 0.001). Effect of solid content on Newtonian viscosity was described by linear as well as power law models depending upon the temperature studied. The combined effect of temperature and solid content on Newtonian viscosity of inulin solution was described by power law type equation and represented as η = 0.8835* (Xs)(0.0731) *Exp(296.410/T), (r = 0.9538, p < 0.001, rmse% = 0.15) Where η is Newtonian viscosity in mPa s, Xs is solid content in % and T is temperature in Kelvin (K).