Whole wheat flour is a food raw material rich in macronutrients, but its application in baking industry is limited due to the existence of a large amount of insoluble dietary fiber in bran. In order to make full use of this resource, we first screened twelve cellulase-producing strains, and then extracted soluble dietary fiber (SDF) from whole wheat flour after fermentation with 3 strains of Aspergillus sp. and 2 strains of Bacillus sp., respectively. The effects of different strains on nutritional characteristics, SDF yield, structure improvement, and antioxidant activity of whole wheat flour were compared. The results showed that fermentation of whole wheat significantly increased the yield of SDF, the content of nutritive active substances, and improved the physicochemical structure and antioxidant activity of SDF in vitro. Scanning electron microscopy (SEM), X-ray diffraction and liquidity characteristics show that the fermentation to make whole wheat SDF has more porous microstructure and crystallinity of lower molecular weight. Fourier transform infrared spectrum showed that there were differences in functional group types between C-SDF and F-SDF. These changes together improved the hydration performance and antioxidant activity of whole wheat SDF, including water holding capacity, oil holding capacity, cholesterol adsorption, DPPH, ABTS and hydroxyl radical scavenging, and lipase activity inhibition. Bacillus sp. SH and Aspergillus oryzae Y21 are ideal strains for fermentation of improved whole wheat, which has the potential of antioxidant properties while improving nutritional properties and food quality.

Compared to refined wheat flour, whole wheat flour contains higher nutrients, but its high content of dietary fiber can have a significant impact on the quality of the final product. Therefore, how to enable consumers to obtain health benefits from whole wheat flour and improve the processing performance of whole wheat products has become a concern. The purpose of this study is to apply two strains Bacillus sp. SH and Aspergillus oryzae Y21 with cellulase production capacity and study their adaptability in whole wheat dough. The results indicate that the addition of cellulase-producing strains enhanced the acid production ability of whole wheat dough, rapidly reduced its pH value and insoluble dietary fiber content, and significantly increased the water-soluble arabinoxylan and water-soluble dietary fiber content. During the fermentation process, the viscoelasticity of the dough decreased, free sulfhydryl content increased, wet gluten content decreased, and the degree of reduction was consistent with the degree of acidification. Moreover, the proteolytic activity of the dough was increased, and the hydrolysis of gliadin was the most extensive. Bacillus sp. SH showed a higher advantage and has been used in whole wheat bread making. Increasing the proportion of strain SH in whole wheat bread can improve the structural characteristics and texture of the bread. When SH (5 × 10⁷ CFU/g) is added to whole wheat bread, its hardness, elasticity, chewiness, and resilience can be similar to those of bread made from control group wheat flour, far exceeding that of whole wheat bread without adding SH. The addition of cellulase producing strains has obvious advantages in the development of whole-wheat dough, and also promote the development of whole wheat fermented foods as staple foods.