High-speed shearing, complex enzymatic hydrolysis and high-speed shearing combined with enzymatic hydrolysis were applied to modify okara dietary fiber, and the changes of their physicochemical properties, structure and prebiotic activity were studied. The results showed that the three modification methods could significantly improve the water holding capacity, swelling capacity and oil holding capacity of okara dietary fiber (P＜0.05). The modified okara dietary fiber had more soluble components, smaller particle size and looser microstructure. FT-IR results showed that there was no obvious change in the distribution of characteristic absorption peaks of the modified okara dietary fiber, but the intensity of some peaks was weakened. XRD results showed that the modification treatment did not change the crystal configuration of okara dietary fiber. In vitro fermentation experiments showed that the modified okara dietary fiber had a proliferation effect on Lactobacillus acidophilus and Bifidobacterium lactis, and the effect on Lactobacillus acidophilus was more significant. Among the three modification methods, the okara dietary fiber prepared by high-speed shearing combined with enzymatic hydrolysis exhibited the highest prebiotic activities, which was mainly reflected in increasing the number of viable probiotic bacteria and lowering the pH of the medium. Therefore, high-speed shearing combined with enzymatic hydrolysis could be used as an excellent method for the modification of okara dietary fiber, which provided a reference for improving the physicochemical properties and prebiotic activity of dietary fiber and further applications in functional foods.
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