Chapter Wheat (Triticum aestivum) Allergens
Wheat grain endosperm contains 8%–12% of proteins. These proteins are divided into two groups: nongluten proteins (15%–20%) and gluten proteins, making up about 80%–85% of all proteins. Nongluten proteins (soluble proteins) are considered soluble in dilute salt solutions, and albumins (water soluble) and globulins (water insoluble) can be distinguished (Osborne, 1907); despite this some globulins are soluble in salt solutions only at increased temperatures (Singh and Shepherd, 1987), and some hydrophobic protein-binding lipids require more hydrophobic solvents (Singh
et al., 1990). Gluten, described as a ductile substance left after washing out soluble compounds and starch granules from wheat dough, which according to mass consists of 75%–85% of proteins, 5%–10% of lipids, and carbohydrates. It is assumed that gluten means wheat proteins that are insoluble in salt solutions: gliadins and glutenins (Osborne, 1907).