EFFECT OF SHEAR RATE ON THE VISCOSITY OF SOLUTIONS OF GUAR GUM AND LOCUST BEAN GUM

The apparent viscosities of aqueous solutions of guar gum and locust bean gum have been measured over a range of shear rates from 14 to 1142 s−1. Comparable measurements were also made on gum solutions to which glucose, sucrose or glucose syrup had been added. For all the solutions the variation of relative viscosity with shear rate fits a power law equation. Addition of sugar has no effect on the non‐Newtonian behaviour of the gum solutions. The relative viscosity of the gum in the sugar solutions is lower than in water. The ratios of the relative viscosities closely correspond with the ratios of the intrinsic viscosities. This is interpreted in terms of a smaller extension of the gum molecule in the sugar solution. Copyright © 1979 John Wiley & Sons, Ltd