Résumé
Adsorption from Acacia gum of hyperbranched arabinogalactan-proteins (AGPs) to oil–water interfaces has been extensively studied and is known to contribute to colloidal stabilization of emulsions. Interfacial tension and rheological analyses revealed AGPs form a viscoelastic interfacial structure through a 3-phase mechanism. Yet, the role of water is generally not considered, even though it is the major and the most dynamic component of the oil-gum-water structure. This article aimed to explore the importance of oil–water interactions on the ability of hydrated Acacia gum to form a dehydrated structured oil-gum-water interphase. Interfacial tension and dilatational rheological measurements were performed using oils differing in hydrophobicity. While the hydrophilic characteristics of AGPs are largely predominant due to their polysaccharide content, their adsorption mechanism is similar to that of proteins, i.e. it is favored near highly hydrophobic interfaces. A volumetric Acacia gum adsorption mechanism is proposed based on the assumptions i) favored interaction energy between water and oil, in particular OH-containing oils involving hydrogen-bond, limits the AGPs interfacial properties, and ii) the surface pressure is a direct measure of the change in the interfacial thermodynamic activity of water molecules. An important issue is the possible emergence of a gel-like transient dissipative structure at the origin of the final elastic interface.