Study on the mechanism of structure modification of amylopectin co-crystalized by sodium chloride to promote disulfide bond formation of alkali-soluble glutenin

Abstract

Strength and stiffness are the main characteristics of high-quality dough products. As one of the key components to endow those functions to noodles, formation of disulfide bonds in alkali-soluble glutenin (ASG) is very important. Interaction of ASG and co-crystalized wheat amylopectin with NaCl could prompt formation of disulfide bonds of ASG and its mechanism was deduced in the paper. The results showed that the disulfide bonds contents of ASG were increased significantly by interaction with co-crystalized wheat amylopectin. The co-crystalized wheat amylopectin with 2% NaCl for 24 h at 30 °C was distinguished by the Mn distribution of 0.55–0.95 × 106 g/mol, more chains with 18∼24 glucose residues being grafted from chains of 4∼7 glucose residues during the eutectic process, presence of the weak resonance enhancement at 96.5 ppm, molecular aggregate diameter less than 120 μm, and only one of X-diffraction angles 2θ at 20.2°. In the process of interaction, Qβ, Qδ, Yγ, Yε of ASG and C1, C6 of what amylopectin involved in the formation of disulfide bond, the contents of intermolecular β-sheet decreased and those of intra-molecular aggregation extended β-sheet and random coils increased. The peak melting temperature and melting enthalpy of the mixture decreased significantly after co-crystallized wheat amylopectin interacted with the ASG. Co-crystalized wheat amylopectin with NaCl can be used as a reinforcing agent of wheat flour.