Solution properties of conventional gum arabic and a matured gum arabic (Acacia (sen) SUPER GUM)

Dilute solution properties of two specially matured gum arabic samples (EM1 and EM2) were compared to the conventional gum (EM0) using static light scattering. The apparent molar mass (M-w,M-pp) and radius of gyration (R-g,R-app) for the three samples showed unusual concentration dependence. These data were satisfactorily interpreted by a simple association model that takes into account the repulsive interaction among clusters, which allowed us to obtain the true molar mass (M-w(0)) and radius of gyration (R-g(0)). A common power law relation was observed between M-w(0) and R-g(0), giving a somewhat higher exponent than expected for linear and branched polymers in a good solvent. M-w(0) and R-g(0) obtained for the three gums do not differ significantly from each other. However, the data showed clearly a constant increase of the association from EM0 to EM2 with increasing concentration. This is in accordance with the previously observed improved functional properties for the matured products.