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Avis de soutenance de Thèse _ Justine Pincemaille

Justine Pincemaille

Soutiendra sa Thèse

Interactions et Assemblages de Protéines du Gluten/Interactions and assemblies of wheat prolamins

Le 22 novembre 2018 à 9h30 dans la salle 104 dans le château de  l'école Montpellier SupAgro (2 place Pierre Viala, 34060 Montpellier Cedex)


Devant le jury composé de :

Antoine BOUCHOUX, INRA Toulouse (Rapporteur)
Denis RENARD, INRA Nantes (Rapporteur)
Christophe CHASSENIEUX, Université du Mans (Examinateur)
Marie-Hélène Morel, Montpellier SupAgro (directrice de thèse)
Laurence Ramos, Université de Montpellier (directrice de thèse)
Amélie Banc, Montpellier SupAgro (co-encadrant)
Paul Menut, Montpellier SupAgro (co-encadrant)


Abstract :

The aim of this thesis is to provide structural and functional knowledge on wheat gluten proteins. For that, we use the physical methods and the concept of soft matter. We optimize an extraction protocol based on a liquid-liquid phase separation. With this protocol, we obtain protein batches with different glutenin/gliadin mass ratios, which we then study in a 50/50 water/ethanol solvent (v/v). We show that proteins behave like polymer chains in θ solvent in dilute and semi-dilute regime, whose characteristic size are extracted by small angle X-ray and neutron scattering. Moreover, two sizes of objects are evidenced in dilute regime by dynamic light scattering: monomeric proteins with a size around 10 nm which can be associated to α/β, and γ-gliadins and polymeric glutenins with low molecular weight and polymeric assemblies with a size around 100 nm composed of ω-gliadins and glutenins polymers with high molecular weight. These assemblies are revealed by a combination of size exclusion chromatography and asymmetric flow field flow fractionation and allow one to rationalize the phase diagrams of the protein mixtures with temperature. The study of the dynamics of the phase separation of these protein mixtures by small angle X-ray scattering shows that the phase separation proceeds through a spinodal decomposition phenomenon. An arrested phase separation is observed for deep quenches but also at all temperature quenches for the most glutenin rich samples, which are gels in the monophasic regime, as confirmed by rheology.