Regulation of Gluten Protein Structure by Soy Milk to Enhance Wheat Bread Quality

ABSTRACT Background and Objectives Soybean flour has been used to improve the nutritional quality of starch‐based foods, but the addition often negatively affects the volume and texture of bread. This study aimed to investigate the effects of soy milk on wheat gluten proteins and to compare the impact of soy milk with that of conventional soybean flour on bread quality. Findings Compared with the control group (consisting of 500 g wheat flour, 300 g water, 40 g sugar, 5 g salt, and 5 g yeast), the specific volume of bread with 30.0% soy milk increased from 2.88 to 3.68 mL/g, whereas hardness, staling rate, and retrogradation enthalpy decreased. Soy milk addition increased the dough's storage modulus ( G ′) and loss modulus ( G ″), making its elastic properties more dominant. As soy milk concentration increased, the α‐helix content in gluten proteins increased, whereas β‐sheet content decreased. Furthermore, soy milk enhanced the extractability of gluten proteins in SDS solution and inhibited the formation of insoluble protein macropolymers. Conclusion Soy milk reduced the overall aggregation of gluten proteins by inhibiting the formation of intermolecular disulfide bonds, and had a significantly better effect than soybean flour on the specific volume, texture, and staling rate of bread. Significance and Novelty This study filled a research gap on the application of soy milk in bread, suggesting its potential as a natural and healthy additive in industrial bread production.