Fractionation and Physicochemical Studies of AcaciaSenegal Gums

Abstract

The chemical and physicochemical characteristics of five authenticated A. senegal gum samples from trees of varying age have been investigated. A. senegal was fractionated by a successive non-solvent fractionation technique using ethanol and acetone as a fractionation agent separately. The fractions were found to be different from the whole gum in terms of molecular characteristics. The molecular mass distribution was determined by gel permeation chromatography (GPC-MALLS) with on-line monitoring using light scattering, refractive index and UV absorbance detectors. The result shows that three main component designated arabinogalactane protein (AGP), arabinogalactane (AG) and glycoprotein (GP) known to be present in A. senegal could be present in their fractions. The weight average molecular weight of A. senegal ranged from 0.808 - 1.334 X 106 g/molwith Mw/Mn ranged from (2.89-4.42). The SG415-20 sample that from the 10-15 years old tree shows high molecular weight, high viscosity and produce emulsion which were stable under accelerate stress condition. All ethanol fractions and ( SG-F1A and SG-F3A) gave the best emulsification performance and stability than the starting material (SG-control) dependent on the protein distribution and its association with the high molecular weight fraction (AGP). All emulsion of ethanol and acetone fractions of A. senegal show low degrees of polydispersity and droplet size compared to the starting material indicating uniformity, clean fractionation and increased adsorption of protein on the oil droplet surface