The molecular mechanism of enhanced heat-induced polymerization behavior of gluten by mixed β-conglycinin and hydrolysates of glycinin

Abstract

The selectively hydrolyzed soy protein composed of β-conglycinin (7S) and glycinin hydrolysates (GH) can improve the quality of cereal products by enhancing the polymerization behavior of gluten. To clarify the potential mechanism, 7S and GH were isolated and combined in varied ratios to examine the effects on the thermal polymerization of gluten. The results demonstrated that both 7S and mixed 7S and GH promoted thermal polymerization of glutenin and gliadin by facilitating the formation of disulfide (SS) bonds, with the optimal effect observed at equal level of 7S and GH. 7S primarily promoted the formation of SS bonds by unfolding the gluten molecular structure upon heating, while the synergistic effect of 7S and GH enabled the polymerized gluten to adopt a more folded conformation with stronger stability than that of 7S. The mixed 7S and GH significantly enhanced the polymerization capacity of α-/γ-gliadins into glutenins, especially for γ-gliadin. The polymerization of gliadin and high molecular weight glutenin subunits (HMS) was promoted by mixed 7S and GH, while the involvement of low molecular weight glutenin subunits (LMS) was inhibited. By promoting gliadin unfolding, 7S and GH enhanced the polymerization tendency of γ-gliadin D2, while the folding behavior suppressed LMS PTDUCD1 participation in cross-linking. This study could provide theoretical support for optimizing the gluten network in wheat-based products supplemented with soy protein and for developing efficient improvers to enhance the techno-functionality of cereal products.