  We investigate the structure of gluten polymer-like gels in a binary mixture
of water/ethanol, $50/50$ v/v, a good solvent for gluten proteins. Gluten
comprises two main families of proteins, monomeric gliadins and polymer
glutenins. In the semi-dilute regime, scattering experiments highlight two
classes of behavior, akin to standard polymer solution and polymer gel,
depending on the protein composition. We demonstrate that these two classes are
encoded in the structural features of the proteins in very dilute solution, and
are correlated with the presence of proteins assemblies of typical size tens of
nanometers. The assemblies only exist when the protein mixture is sufficiently
enriched in glutenins. They are found directly associated to the presence in
the gel of domains enriched in non-exchangeable H-bonds and of size comparable
to that of the protein assemblies. The domains are probed in neutron scattering
experiments thanks to their unique contrast. We show that the sample
visco-elasticity is also directly correlated to the quantity of domains
enriched in H-bonds, showing the key role of H-bonds in ruling the
visco-elasticity of polymer gluten gels.
