CHARACTERIZATION OF COMMERCIAL SAMPLES OF GUM-ARABIC

Six commercial gum arabic samples and authenticated samples of gum from Acacia senegal and Acacia seyal have been characterised using a range of chemical and physicochemical techniques including determination of specific rotation, sugar composition, nitrogen and amino acid content, and molecular mass distribution. Although some of the gums have slightly different chemical and physicochemical characteristics, gel permeation chromatography shows that each consists of essentially three molecular mass fractions classified as an arabinogalactan, an arabinogalactan-protein complex, and a glycoprotein. The proportions of each varied for the individual samples. The gums were tested using a specifically developed enzyme-linked immunosorbent assay which can identify gum from A. senegal and chemically related species. Their interaction with the antibody could be correlated with differences observed in their molecular compositions. Such evidence will assist in their chemotaxonomic classification.