Abstract: In order to improve the emulsification performance of gum arabic (GA), in the present work, glyceryl monolaurate (GML) was grafted with GA. The emulsifying properties and the effect on the stability of oil-in-water emulsions of various grafted products (GML-GA) prepared at different mass ratios of GML to GA of 0%, 5%, 10% and 20% were contrastively investigated. Bulk rheological results indicated that both GA and GML-GA aqueous solutions behaved as Newtonian fluids. The emulsifying properties of GML-GA and the stability of oil-in-water emulsions with GML-GA were significantly enhanced in comparison with GA. The emulsifying properties of GML-GA were improved and then decreased with increasing the GML content, and the best emulsification performance was obtained at a GML to GA ratio of 10%. The emulsification activity of GA was attributed to its content of arabinogalactan protein (AGP). As GML molecules were probably mainly grafted onto AG, the most abundant component in GA, the improved emulsification of the GML-GA products was due to the presence of both AGP and GML-grafted AG.

Key words: gum arabic, glyceryl monolaurate, emulsifying properties, emulsion stability, grafting modification, natural emulsifier