With the demography growth, there is a huge pressure on protein demand, and the development of plant based proteins is required for a future sustainable food production. Plant proteins are efficient to stabilize interfaces in foams or emulsions, and the understanding of physical mechanisms at the origin of their interfacial behavior is important to develop new products. We investigate the adsorption of wheat grains (gliadin) and sunflower seeds (helianthinin) proteins, at air-water and oil-water interfaces, respectively. A combination of tensiometry, dilatational viscoelasticity and ellipsometry measurements is used to determine the adsorption mechanisms, and characterize the structure and properties of the interfacial protein films formed with different bulk protein concentrations. We demonstrate that a diffusion-controlled adsorption occurs at low bulk protein concentration for helianthinin whereas this mechanism occurs whatever the bulk concentration for gliadins. Surface pressure-induced film relaxation through conformation changes of proteins at the air-water interface is identified for gliadin whereas surface aggregation is observed at high helianthinin concentration. Overall, our experimental results highlight that structural flexibility of proteins appears as a key factor for their interfacial activity.

La possibilité pour un fluide viscoélastique de se fracturer a été mise en évidence pour la première fois dans les années 60 [1]] mais reste beaucoup moins documentée [2] que l’étude de la fracturation des matériaux solides Les hydrogels transitoires représentent une classe de matériaux viscoélastiques particulièrement bien adaptée pour l’investigation de fractures dans les fluides viscoélastiques, car leurs temps de relaxation et leur modules élastiques sont facilement modulables. Nous illustrons quelques aspects de la nucléation et de la propagation de fractures dans des réseaux transitoires modèles constitués de micelles se tensio-actifs pontées par des polymères téléchéliques en solution aqueuse. Deux géométrie seront considérées : cellule de Hele-Shaw [3] et rhéomètrie extensionnelle [4].[1] JF Hutton. Nature 200 (1963) 646
[2] C. Ligoure and S.Mora, Rheologica Acta, 52 (2013) 91-114 [3] , Foyart G., Ligoure C., Mora S., Ramos L. ACS Macro Letters, 5 (2016) 1080-1083 [4] , Arora S., Shabbir A., Hassager O., Ligoure C., Ramos L., JOR 61 (2017).1267-1275

The origin of the unique rheological properties of wheat gluten, the water-insoluble protein fraction of wheat grain, is crucial in bread-making processes and questions scientists since the 18th century. Gluten is a mixture of two types of proteins, monomeric gliadins and polymeric glutenins, formed by subunits linked via disulfide bonds. To better understand the respective role of gliadins (Gli) and glutenins (Glu) in the supramolecular structure of gluten and its link to rheology, we have developed a model gluten system using a food-grade solvent, which allows quantitative comparisons with theoretical models for synthetic polymers [1]. Thanks to an experimental protocol based on a liquid-liquid phase separation, we can extract, from industrial gluten, gluten protein fractions with contrasted mass ratios Glu/Gli (from 0.04 to 2). Stable gluten protein suspensions in a water/ethanol mixture solvent over a wide range of concentrations can be produced. Using scattering techniques, we demonstrate that blends of Gli and Glu exhibit features characteristic of branched flexible polymer chains in a good solvent, and form in a dilute regime large Glu-rich protein assemblies [2]. In the semi-dilute regime, we evidence the existence of large zones (of typical size 60 nm) rich in hydrogen bonds [3]. We show that hydrogen bonds are responsible for the spontaneous sample gelation, whose concentration dependence can be quantitatively accounted using percolation theories developed for polymer gels [4]. Overall, our experimental results illustrate the relevance of model gluten gels to unravel the unique and complex behavior of gluten. [1] Banc, Dahesh, Wolf, Morel, Ramos. Journal of Cereal Science 75, 175 (2017). [2] Dahesh, Banc, Duri, Morel, Ramos. J Phys Chem B 118, 11065 (2014). [3] Banc, Charbonneau, Dahesh, Appavou, Fu, Morel, Ramos. Soft Matter 12, 5340 (2016). [4] Dahesh, Banc, Duri, Morel, Ramos. Food Hydrocolloids, 52, 1 (2016).

Materials are the key roadblocks for the commercialization of energy conversion devices in fuel cells andsolar cells. Significant research has focused on tuning the intrinsic properties of materials at the nanometerscale. The soft template mediated controlled fabrication of advanced nanostructured materials isattracting considerable interest due to the promising applications of these materials in catalysis and electrocatalysis.Swollen hexagonal lyotropic liquid crystals (SLCs) consist of oil-swollen surfactant-stabilized1D, 2D or 3D nanometric assemblies regularly arranged in an aqueous solvent. Interestingly, the characteristicsize of the SLCs can be controlled by adjusting the volume ratio of oil to water. The non-polarand/or polar compartments of the SLCs can be doped with guest molecules and used as nanoreactorsfor the synthesis of various metals (Pt, Pd, Au, etc.), conducting polymers and composite nanostructureswith controlled size and shape. 1D, 2D and 3D mono- and bimetallic nanostructures of controlled compositionand porosity can also be fabricated. These materials have demonstrated impressive enhancementsof their electrochemical properties as compared to their bulk counterparts and have been identifiedas promising for further implementation in energy harvesting applications. In this review article,recent research materials are described regarding the development of functional materials with muchimproved performances for catalysis applications. This review addresses a brief overview of swollen hexagonalmesophases as nanoreactors, describes examples of nanostructured materials synthesized inthese nanoreactors, shows several examples of the energy conversion applications in solar light harvesting,fuel cells etc. and also summarizes the associated reaction mechanisms developed in the recent literaturefor enhanced catalytic activity.