Studies on Acacia exudate gums: Part VI. Interfacial rheology of Acacia senegal and Acacia seyal

The effect of concentration, ageing and enzyme degradation on the interfacial rheology at the liquid/air (L/A) and liquid/liquid (L/L) interface of aqueous solutions of the gum exudates from Acacia senegal and Acacia seyal have been studied. Both gums had film forming capabilities which increased as a function of time and concentration. The interfacial elasticity of the A. senegal gum samples was greater than that of the A. seyal gums and increased with increasing arabinogalactan protein (AGP) content of the A. senegal gums and their overall protein content. When the AGP was degraded by proteolytic enzyme the interfacial viscoelasticity was lost for both A. senegal and A. seyal gums. The different interfacial elasticity and viscosity of these two gums at the oil–water interface may reflect their well known differing abilities to maintain long term emulsion stability.