Evaluating the effect of salt on gluten protein interactions in dough via solvent solubility profiling

Abstract

To investigate how sodium chloride (salt) influences protein-protein interactions in wheat flour dough, protein solubility was measured in 1-propanol, acetic acid, and urea to assess the relative strength of hydrophobic interactions, electrostatic forces, and hydrogen bonds, respectively. Results of size exclusion high performance liquid chromatography and two-dimensional fluorescence difference gel electrophoresis showed that salt promotes high molecular weight glutenin to aggregate through electrostatic and hydrophobic interactions and become insoluble at early stage of dough mixing, and through electrostatic interactions after the mixing peak. Higher amount of salt did not cause the proteins to aggregate through hydrogen bonds. With the increase of salt concentration, free SH groups in monomeric proteins decreased but not in polymeric proteins. Addition of salt resulted no formation of additional disulfide bonds between polymeric proteins. Salt affects dough properties mostly through its influence on electrostatic interactions between polymeric proteins, and hydrophobic interactions at the early stages of dough mixing.