Optimization and Characterization of Extraction Technology of Soluble Dietary Fiber from Yam Peel Residue

In order to fully exploit the utilization value of Chinese yam peel, the optimal extraction conditions of soluble dietary fiber (SDF) from Chinese yam peel residue were investigated by orthogonal experiment. The extracts were characterized by X-ray diffraction (XRD) pattern, Fourier infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). And the physical and chemical properties of its swelling capacity (SC), water holding capacity (WHC) and oil holding capacity (OHC) were determined. The results showed that the optimal extraction process was 90 min, NaOH concentration was 12 g/L, liquid-solid ratio was 40:1(mL:g), and extraction temperature was 80 ℃. Under the optimal process, the SDF yield of yam peel residue was 11.52%±0.23%. SDF of yam peel residue belongs to cellulose type I, and its infrared absorption peak showed typical polysaccharide absorption peak. SEM results showed that the SDF of yam peel residue was a loose structure formed by many fine particles. Compared with SDF of yam peel, SDF of yam peel residue had better expansion rate, water holding capacity and oil holding capacity (7.63±0.32 mL/g, 9.81±0.21 g/g, 4.45±0.24 g/g, respectively). In conclusion, SDF of Chinese yam peel residue had good physical and chemical properties, which made it potential value as an effective ingredient in functional food.