Black rice flour‐induced changes in gluten conformation in fresh, pre‐fermented and frozen dough

Summary Black rice flour greatly enriches the nutrition of flour products, and also alleviates the quality deterioration of frozen dough to a certain extent, but the gluten‐influenced mechanism remains unclear. The effects of black rice flour with different particle sizes on protein molecular weight distribution, secondary structure, fluorescence characteristics, thermogravimetric properties, and chemical interaction of the fresh dough (FD), pre‐fermented dough (PD), and thawed dough (TD) were investigated. The addition of black rice flour resulted in the breaking of disulfide bonds in the FD and an increase in the content of total SDS‐extractable protein. However, the depolymerization of large glutenin polymers in the PD and TD of the composite flour system was lower than wheat flour system, especially in the dough with small particle size black rice flour. As the particle size of black rice flour decreased, the intermolecular force of the composite flour dough system is more prominent, of which the hydrophobic interaction force contributes the most considerable value. In addition, TD in the composite flour system has less weight loss than that of wheat flour system. Therefore, adding black rice flour reduced the deterioration of gluten protein, and the small particle size of black rice flour showed advantages.