Ball Milling Combined with Alkaline-Assisted Enzymatic Extraction Improved the Physicochemical and Functional Properties of Soluble Dietary Fiber from Herba Lophatheri

Soluble dietary fiber (SDF) was extracted from Herba Lophatheri by enzymatic extraction, ball milling-assisted enzymatic extraction, alkaline-assisted enzymatic extraction, and ball milling combined with alkaline-assisted enzymatic extraction. The yield of SDF was determined, the four SDFs were characterized by high performance liquid chromatography (HPLC), nano-laser particle size analyzer, rheometer, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD) and differential scanning calorimetry (DSC), and their water-holding capacity, oil-holding capacity, and antioxidant activity were analyzed and compared. The results suggested that all SDFs had the typical structure of polysaccharides and the same crystal types as cellulose, but their monosaccharide composition and microstructure were different. SDF extracted by ball milling combined with alkaline-assisted enzymatic extraction had the highest yield ((30.03 ± 1.03)%) and water-holding capacity ((4.86 ± 0.1) g/g), high viscosity, and the lowest zeta potential ((-22.83 ± 1.95) mV). Besides, it had a loose porous structure, and potent 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) radical cation scavenging activity ((49.40 ± 0.93)%), indicating strong water-binding capacity, antioxidant activity, and gel-forming capacity.