Preparation of Modified Extruded Wheat Bran by Semi-solid Enzymatic Hydrolysis and Its Effect on the Quality of Bran-containing Steamed Bread

To increase the content of soluble dietary fiber in wheat bran and improve the edible quality of bran-containing flour products, the semi-solid enzymatic modification of extruded wheat bran was carried out with xylanase, and modified wheat bran was added to flour to make steamed bread. The optimum addition amount of modified wheat bran and the effect of modified wheat bran on specific volume, texture and flavor of bran-containing steamed bread were investigated. The results showed that the content of soluble dietary fiber in the modified wheat bran reached 6.24%, which was 89% higher than the original wheat bran, when the enzymatic hydrolysis time was 4 h, the amount of xylanase was 1000 U/g wheat bran, and the liquid-solid ratio was 1.0:1 mL/g. When the content of modified wheat bran was 7.5%, the specific volume of bran-containing steamed bread reached the maximum (3.08 mL/g), and the quality of steamed bread was the best. Compared with the original wheat bran, after adding the modified wheat bran, the hardness and chewiness of the steamed bread decreased by 41.19% and 42.35%, respectively, and the specific volume increased by 25.00%, which were not significantly different with the blank group. The modification of wheat bran not only effectively increased the concentration of pleasant volatile flavor components such as 2-methylpyrazine, but also reduced the unpleasant flavor of raw wheat bran bran-containing steamed bread such as diethylene glycol, dimethyl ether. Therefore, the semi-solid enzymatic hydrolysis of extruded wheat bran can effectively improve the quality of bran-containing steamed bread, and at the same time make it had a strong wheat flavor, which provided a new view for the application of wheat bran in staple food flour products.