hordein

Hordein is a group of prolamin storage proteins found in the seeds of barley (Hordeum vulgare). Together with other gluten components, hordeins form the gluten fraction of barley and are responsible for the characteristic viscoelastic properties of barley dough. Hordeins are rich in proline and glutamine and are soluble in high concentrations of alcohol but poorly soluble in water. They are subdivided into several families, commonly referred to as B-hordeins, C-hordeins, and D-hordeins, which are encoded by multigene families in the barley genome. In the seed, hordeins are synthesized in the endosperm and accumulate in protein bodies as a storage protein reserve for germination.

Hordein proteins contribute to the allergenicity and immunogenicity of barley. They contain epitopes that can trigger celiac disease in susceptible individuals, and barley-specific allergy or non-celiac gluten sensitivity may be related to hordeins. For people with celiac disease, barley is typically avoided or carefully managed; many products labeled gluten-free exclude barley and its hordein.

In food and brewing, hordein content affects processing and quality. Barley gluten is generally less sticky and elastic than wheat gluten, influencing dough handling and beer foam stability. Some barley varieties or processed products aim to reduce hordein content to improve tolerability or to meet specialized dietary needs. Analytical methods such as immunoassays and proteomic techniques are used to detect and quantify hordein in barley-based foods and beverages.