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Emulsions de Pickering stabilisées par des poudres végétales : propriétés et rôle des paramètres de composition et de formulation

Abstract : This study aimed at valorizing vegetal byproducts while offering a bio-sourced, cheap and efficient alternative to conventional surfactants. Oil-in-water emulsions were obtained from finely ground plant powders as the only surfactant material. The resulting dispersed systems, stabilized by solid particles, are so-called Pickering emulsions. The first part of this manuscript describes the influence of the emulsification process (rotor-stator in turbulent regime, sonication and high-pressure homogenization) and of the formulation parameters on the properties of emulsions stabilized by cocoa powder. The role of the different fractions of the powder was determined and a phenomenon characteristic of Pickering emulsions, namely limited coalescence, was identified. We evidenced a structural evolution of the particles ("unwrapping") under the effect of the shear applied during the emulsification process, allowing to increase their performance as stabilizing agents. The influence of the vegetal origin was explored by extending the study to powders deriving from rapeseed and lupin oilcakes. The stability of these emulsions with respect to the elimination of the continuous phase was evaluated using 2 drying techniques, freeze-drying and spray-drying. Dry emulsions rich in oil and redispersable in water were obtained. Finally, the antioxidant properties of vegetable powders before and after the drying process were characterized.
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Submitted on : Monday, March 25, 2019 - 1:25:13 PM
Last modification on : Tuesday, May 26, 2020 - 3:13:08 AM
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Cécile Joseph. Emulsions de Pickering stabilisées par des poudres végétales : propriétés et rôle des paramètres de composition et de formulation. Chimie-Physique [physics.chem-ph]. Université de Bordeaux, 2018. Français. ⟨NNT : 2018BORD0313⟩. ⟨tel-02078469⟩

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