Impact of combined single- or mixed-strain sourdough fermentation and enzyme treatment on the physicochemical, nutritional and baking performance of highland barley-wheat bran flour composite bread

In this study, the combined effect of single- or mixed-strain sourdough fermentation and enzyme treatment on the physicochemical, nutritional, and baking performance of highland barley–wheat bran composite bread was investigated. Key enzymatic activities during sourdough fermentation of highland barley-wheat bran (HW) substrate were reported. The rheo-fermentation properties in dough; the specific volume, crumb firmness, sensory acceptance, staling properties and in vitro starch digestibility of the corresponding bread were reported. The results showed that sourdough fermentation increased the acidity, soluble dietary fiber, water-extractable arabinoxylan, and exopolysaccharide contents of HW substrate. Higher contents were observed in the mixed-than single-strain-fermented sourdough, associated with the higher activities of in situ -synthesized xylanase, β-glucanase, and β-glucosidase enzymes. In dough, compared to unfermented highland barley–wheat bran (HWB) and enzyme-treated highland barley–wheat bran (EB), combined sourdough and enzyme treatment increased the total gas production (higher in enzyme-treated and mixed-strain ( Weisella confusa QS813 and Kluyveromyces marxianus , EQKB) than in enzyme treated and single-strain ( W. confusa QS813 (EQB) or K. marxianus (EKB)). In bread, specific volume increased, crumb firmness decreased, and sensory acceptance greatly improved in the order of EQKB, EKB, EQB, EB, and HWB. Furthermore, in vitro starch digestibility decreased, while the anti-staling properties were enhanced in bread were enhanced. These findings reveal that there was better synergy in the improvement of the nutritional and baking performance of highland barley–wheat bran composite bread when mixed-rather than single-strain sourdough was combined with enzyme treatment. • Combined enzyme and sourdough enhanced nutritional and baking performance of bread. • Better outcomes in mixed-strain than single-strain sourdough with enzyme in bread. • Increased synergy of acidification and enzyme hydrolysis in substrate material. • Increased soluble fiber, EPS, WEAX which stabilized dough, more gas retained. • Improved quality, lower starch digestibility, and staling properties of the breads.