Heat mediated physicochemical and structural changes of wheat gluten in the presence of salt and alkali

To understand the heat mediated cross-linking mechanism of gluten in the presence of salt and alkali, the effects of heating on the physicochemical and structural changes of gluten protein was comparatively investigated in this study. Our results showed that the G′ value of gluten was mediated by heating, while alkali delayed the transition temperature by approximately 20 °C. Salt increased the extensibility of gluten. However, alkali improved gluten strength and toughness. Fluorescence spectroscopy, surface hydrophobicity, and AFM images demonstrated that hydrophobic interactions and aggregations of protein molecular chains were enhanced by both salt and alkali, and heating further promoted these interactions. In addition, alkali reduced the aggregation temperature of large glutenin polymers from 95 to 75 °C according to SE-HPLC profiles. RP-HPLC patterns confirmed that α- and γ-gliadin subunits were more susceptible to heat and polymerized after heating at 95 °C with alkali. QCM-D results showed that alkali promoted protein-protein interactions in gluten, which was positively correlated with temperature. This study consummates the understanding of heating mediated cross-linking mechanisms of gluten with salt and alkali and provides a more comprehensive theoretical basis for the control of gluten properties and quality of wheat products.