Solid-State Fermentation Using Mushrooms Enhances Wheat Bran Functionality and Whole-Wheat Bread Quality

Wheat bran (WB), a by-product of wheat milling, limits the quality of whole-wheat bread because of its high insoluble dietary fiber (IDF) content. This study aimed to investigate the effects of solid-state fermentation on the nutritional and functional properties of WB, using four different mushroom strains, including Pleurotus pulmonarius, Ganoderma lucidum, Pleurotus citrinopileatus, and Hericium erinaceus. Fermentation with P. pulmonarius for 4 days decreased IDF content by 20.2% and increased soluble dietary fiber (SDF) content by 82.17%. Fermentation with G. lucidum for 8 days enhanced phenolic compound content 10.98-fold. Incorporating P. pulmonarius-fermented WB into the dough increased the specific volume of bread by 4.24-15.60% and reduced hardness and chewiness by up to 49.2%. WB fermented with P. pulmonarius displayed greater improvement than WB fermented with the other strains under identical conditions. Correlation analysis revealed that SDF was correlated positively with phenolic compounds and bread volume, but negatively with IDF and dough viscoelasticity, suggesting its key role in improving bread quality. These findings highlight that P. pulmonarius-based fermentation is a sustainable strategy for valorizing WB into high-quality functional ingredients for whole-wheat bread.