gliadiini

Gliadins are a group of alcohol-soluble storage proteins found in wheat gluten, together with glutenins that form the gluten network in dough. They are prolamin proteins rich in proline and glutamine and are soluble in aqueous alcohol but not in water. Gliadins contribute to the viscosity and extensibility of dough, whereas glutenins provide elasticity and strength. In breadmaking, both classes interact to determine the viscoelastic properties of the gluten network.

Classification and structure: Wheat gliadins are divided into four major groups: alpha, beta, gamma, and omega gliadins. They vary in sequence, molecular weight, and electrophoretic mobility. The genes encoding gliadins are clustered in complex multigene families on wheat chromosomes and are highly polymorphic, contributing to the variability of gluten properties among wheat varieties.

Role in health and disease: Some gliadin peptides are highly immunogenic. In celiac disease, ingestion of certain gliadin peptides triggers an autoimmune reaction in genetically susceptible individuals, aided by deamidation of glutamine residues by tissue transglutaminase that increases binding to HLA-DQ2/DQ8. Gliadins also contribute to non-celiac gluten sensitivity and wheat allergies in some individuals. Their immunogenicity varies among gliadin types and individual peptides.

Occurrence and uses: Gliadins are specific to wheat and related cereals; not present in gluten-free grains. They are major components of the gluten complex that determines dough properties in bread, pasta, and other wheat products. Processing methods and wheat breeding aim to modify gliadin composition to adjust dough performance and, in some cases, to reduce health risks in sensitive individuals.