The effect of ultra-fine grinding combined Trichoderma viride fermentation technology on the functional characteristics of wheat bran dietary fiber

Wheat bran is the outer layer of the wheat kernel, packed with fiber, vitamins, and minerals that promote digestive health. It is among the crucial raw materials for dietary fiber (DF). However, over 85% of wheat bran is used for traditional processing such as brewing and feed, resulting in low added value. We used a combined approach of ultrafine grinding and Trichoderma viride fermentation to enhance its biological activity and maximize wheat bran utilization. This method significantly increased the yield of modified soluble dietary fiber (M-SDF) and modified insoluble dietary fiber (M-IDF) from 10.2 to 37.1% and 43.8-67.3%, respectively. Scanning electron microscopy indicated that M-SDF and M-IDF had improved porous spatial structures and larger specific surface areas. Furthermore, the functional properties analysis revealed that M-SDF and M-IDF had higher water-holding and swelling capacities; enhanced antioxidant activity; increased glucose adsorption, cholesterol adsorption, sodium cholate adsorption, and nitrite ion adsorption capacities. Additionally, they exhibited inhibition of α-amylase and pancreatic lipase activities. In summary, the combination of ultrafine grinding and T. viride fermentation proved to be an effective modification method for improving the functional properties of DF, which could expand the applications of wheat by-products.