The role of the proteinaceous component on the emulsifying properties of gum arabic

Gum arabic has been separated into five molecular mass fractions using gel permeation chromatography. Each fraction was shown to be present in varying proportions. A high proportion of the proteinaceous material (60%) is associated with one high molecular mass component, which constitutes <10% of the total gum. This fraction can be degraded enzymically to give products with similar molecular masses to the other fractions. Although gum arabic solutions of >12% (w/w) were required to give stable 20% (w/w) orange oil emulsions of small droplet size, it was demonstrated that only 1-2% of the gum actually adsorbed at the oil-water interface. Further investigation revealed that it was the high molecular mass, protein-rich fraction which predominantly adsorbed and hence is responsible for the gum's emulsifying ability. Stable emulsions could not be produced using enzyme-degraded gum arabic.