Upcycling soybean meal through enzymatic conversion of insoluble fiber into soluble dietary fiber enhanced by ball milling

Insoluble dietary fiber (IDF) in soybean meal, due to the insolubility, is one of the major impediments to upcycle the soybean meal for its value-added use. This study converted IDF to soluble dietary fiber (SDF) using ball milling and enzymatic hydrolysis of the IDF. The impact of ball milling and enzymatic hydrolysis on the physicochemical and functional properties of SDF was evaluated. Cellulase, hemicellulase, xylanase, galacturonase, and arabinofuranosidase were employed for hydrolyzing IDF. The results showed that ball milling significantly reduced the particle size of IDF, facilitating enhanced enzymatic hydrolysis and resulting in SDF with lower molecular weight and varied monosaccharide composition. The synergistic effect of ball milling and enzymatic processes with combination of cellulase-xylanase-galacturonase was evident by the improved conversion rates (69.8%) and altered weight-averaged molecular weight (<5900 Da) of the resulting SDF. Rheological and microstructural analyses of the SDF gel indicated that specific enzyme combinations led to SDF gels with distinct viscoelastic properties, pore sizes, and functional capabilities, suitable for varied applications in the food and pharmaceutical sectors. This comprehensive evaluation demonstrates the potential of optimized physical bioprocessing techniques in developing functional ingredients with tailored properties for industrial use.