Abstract: In this study, we determined the effect of cavitation microjet on the structure and function of okara dietary fiber, a byproduct of aqueous enzymatic extraction of soybean oil. We characterized the molecular structure, crystal structure, water and oil retention capacity, and swelling power as a function of treatment time using Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy and other analytical methods, and clarified the mechanism behind the effect of cavitation microjet on the structure. The results indicated that the water and oil retention capacity of okara insoluble dietary fiber increased to (9.42 ± 0.05) g/g and (3.92 ± 0.05) mL/g, respectively after the treatment. The swelling power increased by 1.6 folds, but the cellulose crystal configuration did not changed. However, the physical form of okara dietary fiber became smaller solid particles. Therefore, cavitation microjet technology can effectively improve the structure and functional characteristics of okara dietary fiber and thus provide technical support for the development and utilization of soybean residues.

Key words: cavitation microjet, okara, dietary fiber, Fourier transform infrared spectroscopy, X-ray diffraction