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Emulsions Stabilized by Gum Arabic: Composition and Packing within Interfacial Films

Atgié, Marina and Masbernat, Olivier and Roger, Kevin Emulsions Stabilized by Gum Arabic: Composition and Packing within Interfacial Films. (2019) Langmuir, 35 (4). 962-972. ISSN 0743-7463

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Official URL: https://doi.org/10.1021/acs.langmuir.8b02715

Abstract

Gum arabic is a heterogeneous natural hydrocolloid commonly used in the agro-food industry to provide metastability to oil-in-water emulsions. Since aqueous solutions of gum arabic contain a complex mixture of protein/polysaccharide conjugates, the composition of interfacial films is expected to differ from the bulk composition. Here, we investigate the composition of interfacial films in oil/water emulsions stabilized by gum arabic at various concentrations, pH and salinity. Using both size exclusion and hydrophobic interaction chromatography separations, we show that the interface is enriched in protein-rich species displaying a broad range of sizes. These species are irreversibly adsorbed as monolayers at the oil/water interface. We observe that the surface coverage density, or packing, of the adsorbed species at oil/water interfaces drastically increases with both the increasing gum concentration and decreasing ionic repulsions, through increasing the ionic strength or decreasing the pH. Strikingly, these packing changes correspond to only minor composition changes in the adsorbed layer. We thus conclude that the key parameter modified in different formulations is the conformation of the adsorbed species rather than their composition distribution. These findings can be readily used to adjust the amount of gum arabic necessary to produce metastable emulsions.

Item Type:Article
HAL Id:hal-02284642
Audience (journal):International peer-reviewed journal
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - INPT (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UPS (FRANCE)
Laboratory name:
Funders:
Agence Nationale de la Recherche - ANR (FRANCE)
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Deposited By: Loetitia MOYA
Deposited On:12 Sep 2019 06:46

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