AbstractBackground and objectivesIn this study,Kluyveromyces marxianuswith ability to produce β‐glucosidase was used to preferment wheat bran (WB) and release a mixture of natural enzymes for improving dough performance and bread quality. Five different enzyme activities were analyzed. The effect of the prefermented WB with enzyme mixture on stickiness and microstructure of dough, ferulic acid release in bread, and molecular weight distribution of arabinoxylan were evaluated using Texture Analyzer, scanning electron microscopy (SEM), HPLC, and high‐performance gel filtration chromatography (HPGFC).FindingsKluyveromyces marxianusexhibited abundant extracellular β‐glucosidase activity (up to 6.98 U/g). The main enzymes released in prefermented bran were endoglucanase and exoglucanase, β‐glucosidase, xylanase, and ferulate esterases. These enzymes were active during bread making (only prefermented bran added as improver or combined with xylanase) and affected solubility and molecular weight distribution of dietary fiber, which resulted in positive improvement of dough performance, release of phenolic acid, and overall quality of the breads. The changes observed were attributed to the extracellular enzymes fromK. marxianusand endogenous enzymes activated during prefermentation, thus enhancing the WB functionality in bread.ConclusionsWheat bran bioprocessing using high enzyme producing yeasts increases functional application of wheat bran in baked products.Significance and noveltyThis study added new knowledge for developing a natural enzyme‐based improver for bran‐enriched baked products in the food industry.