Dynamic behaviors of protein and starch and interactions associated with glutenin composition in wheat dough matrices during sequential thermo-mechanical treatments

Abstract

To clarify the detailed behaviors of protein, starch and interactions during complex dough processing, structural changes in dough protein and starch during continuous Mixolab processing were investigated using wheat near-isogenic lines carrying high-molecular-weight glutenin subunits 1Dx5 + 1Dy10 (5 + 10) or 1Dx2 + 1Dy12 (2 + 12) at the Glu-D1 locus. A more stable gluten network including disulfide bonds and hydrophobic interactions, was formed in the 5 + 10 dough before dough weakening at 53.5 °C, than in the 2 + 12 dough. Thereafter, thermo-mechanical treatment induced the depolymerization of gluten until starch gelatinization peak at 74.6 °C; however, from the peak to trough viscosity at 82.8 °C, additional monomeric proteins were incorporated into the repolymerized proteins characterized by increased disulfide bonds, hydrogen bonds, and β-sheets. Generally, the protein aggregates of 5 + 10 showed a higher degree of polymerization and better stability than those of 2 + 12 during dough processing, which significantly slowed starch gelatinization and recyclization. Moreover, stronger interactions between monomeric proteins and amylose/short-branch starch via glycosidic and hydrogen bonds were found in 5 + 10 dough during starch pasting and retrogradation. The findings demonstrate the feasibility of optimizing the texture and digestibility of wheat-based food products by regulating the behaviors and interactions of proteins and starch during dough processing.

Keywords: Gluten network; High-molecular-weight glutenin subunits; Mixolab; Protein–starch interaction; Starch gelatinization.