Résumé
Producing wheat gluten gels with tunable mechanical properties via simple sol-gel routes would facilitate their processing into plant protein-rich food products. However, a standard gluten is a very elastic mass with a high concentration of proteins in water and is hardly processable except using high shear harsh extrusions. The wheat proteins, which are responsible for the viscoelastic properties of gluten, are among the most complex proteins families, with extremely broad polymorphisms and polydispersities, and are moreover insoluble in water, rendering rational studies difficult. We use here a novel extraction protocol that allows the formulation of stable ethanolic suspensions of gluten proteins over a wide range of concentrations. Viscoelasticity measurements show a spontaneous and concentration-dependent gelation of the suspensions, which we find to be driven by the slow formation of hydrogen bonds. We successfully rationalize our data using percolation models and relate the viscoelasticity of the gels to their fractal dimension measured by scattering techniques. The novel gluten gels display self-healing properties and their elastic plateaus covers several decades. In particular very soft gels suitable for processing can be produced.