Structure and rheological properties of acacia gum dispersions

The structure of acacia gum molecules was determined using size exclusion chromatography coupled to multi-angle laser light scattering, refractometry and viscosimetry. Results revealed the presence of many molecular species, including large aggregates, the arabino-galactan protein fraction (AraGP), the arabino-galactan fraction (AraG) and the glyco-protein fraction (GP). The Mw of the two major fractions AraGP and AraG were 2.3 106 and 2.7 105 g mol−1, respectively. The [η], Rg and Rh of the acacia gum sample were 0.23 dl g−1, 14.2 and 11.9 nm, respectively. From the determination of Rg/Rh ratio (1.2) or the exponent ν (0.55) of the power-law relationship between Rg and Mw, it was tentatively suggested that acacia gum molecules displayed a random coil shape.