Effects of water-unextractable arabinoxylan from wheat processing wastewater on the quality characteristics of multigrain bread

The water-unextractable arabinoxylan (WUAX) was extracted from the wheat processing wastewater to replace the flour in the bread formula and improve the quality characteristics of the multigrain bread. We investigated the effects of WUAX substitution concentration (0, 2.5, 5, 7.5 and 10 g/100 g high gluten flour weight) on multigrain bread texture, microstructure, color difference variation, relative crystallinity, moisture distribution, and sensory evaluation. Within the specified range, the bread hardness increased by 4.0 N, a negative effect on the bound water in bread and significant changes in the color difference were observed. The optimal substitution level was 7.5%, increasing the crude fiber content by 33% (dry weight ratio) and reducing the starch content by 10%, maintaining the specific volume and hardness similar to the control group. The scanning electron microscopy X-ray diffraction (XRD) measurements showed that WUAX affected the aggregation of protein and starch, and reduced the relative crystallinity of bread, retarding bread staling. The WUAX replacing flour (7.5% replacement level) also provided good sensory evaluation. Overall, WUAX boosts bread's dietary fiber content while lowering its starch proportion. Although WUAX had negatively impact on bread texture, a 7.5% substitution level could minimize these effects. This study offered insights for the dietary applications of WUAX from wheat processing wastewater.