Study of the effect of deamidation on the properties of degraded wheat gluten

The aim of this study was to investigate the characteristics of the degradation of wheat gluten by deamidation using carboxylic acids (succinic acid). The changes in succinic acid deamidated wheat gluten (SDWG), during hydrothermal treatment, were characterized using physicochemical indexes such as the deamidation degree (DD), nitrogen soluble index (NSI), degree of hydrolysis (DH), thermal characteristics, molecular weight distribution (MWD), and secondary conformation of proteins. The results indicated that, during modification, the degradation of wheat gluten molecules occurred in a stepwise manner. During the first 10 mins, the DD (from 24.65% to 64.79%), NSI (from 11.55% to 91.31%), glass transition temperature (from 50.70 to 61.80), and enthalpy [from 1.73 to 2.35 J/(g·K)] all significantly increased, while the increase of DH was less than 1%. Additionally, sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and size exclusion-high-performance liquid chromatography (SE-HPLC) showed that SDWG had a tendency to degrade; infrared spectra indicated that the flexibility of SDWG generally decreased. In particular, significant changes in MWD and secondary conformation were observed at 6 min after the reaction started. These results indicate that succinic acid has a high specificity for the deamidation of wheat gluten upon hydrothermal treatment and that the degradation of wheat gluten is a stepwise process with different stages. ©, 2015, South China University of Technology. All right reserved.