Abstract
The rheological behaviours of aqueous solutions of gum arabic were investigated in this study. The gum arabic solutions at concentrations of 10 wt% and 30 wt% showed shear thinning flow behaviour. Viscosity of the non-centrifuged solution was higher than that of the centrifuged solutions at low shear rate region, suggesting that the air bubbles in the solution contribute to increasing of viscosity. The gum arabic solution can contain many air bubbles in the dissolving process, since the gum arabic has high surface activity in the aqueous solution. Air bubbles in the solution of gum arabic can be partially removed by centrifugation of the solution. The Newtonian regime can be observed at high shear rate region in the both non-centrifuged and centrifuged solutions and the viscosity of non-centrifuged solution was the same as that of centrifuged solutions. In dynamic rheological behaviours, the storage modulus of non-centrifuged solution was higher than that of centrifuged solution at low frequency region. The storage modulus of both non-centrifuged and centrifuged solutions increases with time when temperature is changed from 10℃ to 32℃, as in the gelling process.
