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Emulsions Stabilized by Gum Arabic: How Diversity and Interfacial Networking Lead to Metastability

Atgié, Marina and Chennevière, Alexis and Masbernat, Olivier and Roger, Kevin Emulsions Stabilized by Gum Arabic: How Diversity and Interfacial Networking Lead to Metastability. (2019) Langmuir, 35. 14553-14565. ISSN 0743-7463

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Official URL: https://doi.org/10.1021/acs.langmuir.9b02541

Abstract

Gum arabic is a natural hydrocolloid composed of adiversity of amphiphilic species consisting of protein chains covalently linked to multiscale porous polysaccharides. Gum arabic is notably used as a food additive (E414) to provide metastability to oil-in-water emulsions, even after extensive dilution. Here, we investigate the mechanism underlying the emulsion stabilizing properties of gum arabic, using a combination of scattering and chromatographic analyses and the design of a harvesting method to collect adsorbed species. Increasing the interfacial packing of amphiphilic species leads to their irreversible interfacial aggregation, which is driven by hydrophobic interactions between protein chains. This aggregation is promoted by the size diversity of amphiphilic species, with smaller species first aggregating at intermediate interfacial packings, followed by larger species at higher packings. The resulting adsorbed layer can be considered as a shell composed of a two-dimensional protein network, irreversibly cross-linked through hydrophobic interactions, which is covalently linked to hyperbranched polysaccharide chains displaying severe conformational changes compared to their bulk structure. This shell is strongly anchored at the oil−water interface by the protein network and provides steric repulsions through the hydrated polysaccharides. Consequently, if such a shell is adequately formed during emulsification, emulsions stabilized by gum arabic may resist extensive mechanical stresses and display a long-term metastability even after drastic environmental changes. This paves the way toward more rational uses of gum arabic as an emulsion stabilizer in formulations and processes.

Item Type:Article
HAL Id:hal-02396769
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Commissariat à l'Energie Atomique et aux énergies alternatives - CEA (FRANCE)
French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UT3 (FRANCE)
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Agence Nationale de la Recherche - ANR
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Deposited On:06 Dec 2019 10:02

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