Rheological Studies of Gum Karaya (Sterculia urens) and Gum Kondagogu (Cochlospermum gossypium)): Tree Gums of India.

Viscosities of different concentrations such as 0.2%w/v, 0.4%w/v, 0.6%w/v, 0.8%w/v and 1%w/v of aqueous Gum Karaya and Gum Kondagogu dispersions were studied at various shear rates. Rheological studies of Gum Kondagogu and Gum Karaya indicated a Non-Newtonian, Pseudo-plastic behavior of its dispersions. 0.6%w/v, 0.8%w/v, 1%w/v of both the gum dispersions were translucent with a slight thicker to thinner consistencies depending on their concentrations. 0.2%w/v and 0.4%w/v concentrations appeared like a fine (Colloidal) dispersions. The Exponential constant ‘N’ values observed for Gum Karaya and Gum Kondagogu dispersions having 0.6%w/v, 0.8%w/v and 1%w/v concentrations were found to be 1.145, 1.285, 1.395 and 1.142, 1.240,1.440 respectively.The yielded Exponential constant values were found to increase with the increase in concentration of the gums. The values of the concentrations for both the gums 0.2%w/v and 0.4%w/v found to be less than ‘1’ indicating the ‘Dilatant’ flow. The Apparent Viscosity (η¹) of Gum Karaya concentrations of 0.6%, 0.8% and 1% were found to be 5.38.8.45 and 16.38 and that with Gum Kondagogu concentrations of 0.6%, 0.8% and 1% were found to be 5.32, 7.54 and 11.72 respectively. The viscosities of both the gum dispersions when treated with different biological buffer solutions were found to decrease slightly with the increase in pH.