Effect of mild thermal treatment on the polymerization behavior, conformation and viscoelasticity of wheat gliadin.

The physicochemical properties of gliadin upon mild thermal treatment were studied in terms of polymerization behavior, conformation and viscoelasticity. Gliadin samples were heated at 40, 60 and 90°C for up to 20min. Results showed that α-gliadin started to polymerize via disulfide (SS) bonds before γ-gliadin at 90°C, resulting in the extractability loss in aqueous ethanol. β-Turn and specific β-sheet structures were partially conversed to α-helices during thermal treatment. Rearrangement of non-covalent forces might contribute to viscosity loss of gliadin at 40 and 60°C. However, the elevated elasticity at 90°C was mainly due to gliadin polymerization while the viscosity variation was resulted from combined effects of non-covalent forces and covalent SS bonds. This study could offer insight into the variation of gliadin characteristics during the early baking process.