Characterization of physicochemical and functional properties of soluble dietary fiber from separate and co-fermented okara by Lactic acid bacteria and Kluyveromyces marxianus C21

The soluble dietary fiber (SDF) was made from separate and co-fermented okara utilizing Lactic acid bacteria (LAB) and Kluyveromyces marxianus C21, and the physicochemical and functional properties of SDF were assessed both before and after modification. The results showed that compared with non-fermented okara, the content of SDF from separate and co-fermented okara utilizing LAB and K. marxianus C21 increased by 16.9%, 19.5%, and 21.6%, respectively. Scanning electron microscopy studies showed that compared to separate and non-fermented okara, co-fermented okara SDF had the most excellent porous surface, the loosest structure, and a greater specific surface area. The ratios of the components of monosaccharides have altered. Additionally, the fermented okara SDFs had reduced particle sizes and spectral patterns similar to those of the non-fermented okara according to particle size distribution and Fourier transform infrared spectroscopy. In addition, co-fermented okara SDF showed increased oil-holding (8.66 g/g), water-swelling (10.33 mL/g), and water-holding (12.87 g/g) capabilities. Additionally, okara SDF's antioxidant, in vitro hypoglycemic, and hypolipidemic properties were all successfully increased by all fermentation treatment groups. In summary, the study's fermented okara SDF offers a high reference value for okara's future use and exploitation, making it a viable functional ingredient.