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Etude de la coacervation complexe entre la beta-lactoglobuline et la gomme d'acacia en solution aqueuse

Abstract : Effects of total biopolymer concentration and protein polydispersity on the formation and stability of coacervates have been investigated in b-lactoglobulin/acacia gum/water mixtures. Blends consisting in native b-lactoglobulin (b-lg) or aggregated one (56% insoluble aggregates at pH 4.75) and acacia gum exhibited phase separation through complex coacervation between pH 3.6 and 5.0. The increase of the total biopolymer concentration reduced the effect of pH and protein to polysaccharide mixing ratio on the formation of coacervates in both mixtures. By contrast, a high polydispersity of the b-lg increased the area of the two-phase region on ternary phase diagrams obtained at pH 4.2. Coacervates and precipitates were formed in presence of protein aggregates, whereas only coacervates were obtained with native b-lg. The size of the coacervates was controlled by the aggregates because of their specific interaction with a fraction of the acacia gum present in the mixture. The structure of the coacervates is characterised by the presence of vacuoles due to the partial coalescence of small coacervates. After interaction with the acacia gum, circular dichroism measurements have shown a shift in the a helical structure of the b-lg. This region is characterised by a high positive charge density. Stability and structuration of coacervates resulted from an equilibrium between flocculation, coalescence and sedimentation phenomena as described by diffusing-wave spectroscopy and confocal laser scanning microscopy. The study of b-lg/acacia gum/water mixtures self-organisation using time-resolved small-angle static light scattering highlighted diffusion and hydrodynamic phenomena resulting in the growth of the structural domains. In some cases, it was possible to describe the complex coacervation kinetics by the spinodal decomposition theory.
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https://tel.archives-ouvertes.fr/tel-00007723
Contributor : Christophe Schmitt <>
Submitted on : Monday, December 13, 2004 - 11:36:21 AM
Last modification on : Tuesday, November 3, 2020 - 4:18:03 PM
Long-term archiving on: : Friday, April 2, 2010 - 8:57:51 PM

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  • HAL Id : tel-00007723, version 1

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Christophe Schmitt. Etude de la coacervation complexe entre la beta-lactoglobuline et la gomme d'acacia en solution aqueuse. Autre. Institut National Polytechnique de Lorraine - INPL, 2000. Français. ⟨tel-00007723⟩

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