Relationship between the molecular characteristics of Acacia gum and its functional properties

International audienceAcacia gum, known as gum Arabic (GA), is a hydrocolloid complex, polysaccharide-based gum exudate. The gum is secreted by the trunk, branches or fruit of Acacia trees (i.e Acacia senegal and Acacia seyal) in response to a scission, injury or fungal infection. Acacia trees are natives to dry areas of the sub-saharian region, from Senegal to East Africa, of which Sudan, Chad, and Nigeria produce nearly 95% of GA exported to the world market. The dried gummy exudate, consisting of soluble fibers of low viscosity, is an interesting edible ingredient for several industrial applications (Williams & Phillips, 2009). Thanks to its technological features, the GA is extensively used in the food, pharmaceutical, printing, textile, and cosmetic industries. Added to liquid food systems, they can adjust and improve their rheological properties. GA generally function as stabilizer, emulsifier, film former, thickener, flocculant and surfacefinishing agent. These intrinsic properties make GA a recognized food additive (E414). They are found in the production of beverages, confectionery, emulsions, flavor encapsulations, bakery products and brewing (Verbeken, Dierckx, & Dewettinck, 2003). These exceptional functional properties are thought to be tightly related to the composition and characteristics of molecular structure of GA. The molecular structure of GA consists of a mixture of highly branched and acidic polysaccharides. The main linear chain is composed of a core of 1,3linked β-D-galactopyranose monomers with branches linked through C-6 but also C-4 or C-2. The branched chains consist of galactose and arabinose terminated by rhamnose and glucuronic acid (Al-Assaf et al.