Gliadins

Gliadins are a group of alcohol-soluble storage proteins found in wheat and related cereals. They are monomeric proteins that, together with glutenins, form gluten, the protein network that gives dough its characteristic viscoelastic properties.

There are four main classes of gliadins: alpha-, beta-, gamma-, and delta-gliadins. They are rich in the amino acids proline and glutamine and contain repetitive sequence motifs. Most gliadins are small to medium polypeptides, generally in the 30- to 50-kilodalton range.

In dough, gliadins contribute viscosity and extensibility, while glutenins provide elasticity. The balance and composition of gliadins influence dough handling, crumb structure, and bread volume. Their properties interact with those of glutenins to determine the overall texture of baked products.

Health relevance is a major area of study. Some peptides derived from gliadins can trigger immune responses in susceptible individuals. In celiac disease, certain epitopes, notably within alpha-gliadin, stimulate intestinal T cells; a highly immunogenic fragment known as the 33-mer has been highlighted for its robustness to digestion. Gliadins are also implicated in wheat allergies and may contribute to non-celiac gluten sensitivity in some people.

Genetic and agronomic aspects: The composition of gliadins varies among wheat species and cultivars. Breeding and biotechnological approaches aim to reduce or modify specific immunogenic gliadin sequences while preserving desirable dough functionality.