Effects of Extraction Methods on the Structural and Functional Characteristics of Dietary Fiber from Auricularia cornea var. Li.

Insoluble dietary fiber (IDF) and soluble dietary fiber (SDF) from Auricularia cornea var. Li. were extracted by alkaline or enzymatic extraction. Our aim was to compare the effects of the two extraction methods on the structural, physicochemical and functional properties of dietary fiber. Scanning electron microscopy (SEM) analysis showed that dietary fiber extracted by enzymatic extraction method had a looser and more complex structure. Fourier transform infrared spectroscopy (FTIR) indicated that all samples showed the characteristic absorption peaks of sugar. X-ray diffraction analysis (XRD) showed that enzymatically extracted dietary fiber had lower crystallinity. Thermogravimetric analysis (TGA) demonstrated that alkaline extracted dietary fiber had higher stability. Enzymatically extracted dietary fiber had waterholding capacity of 10.68–20.79 g/g, oil-holding capacity of 2.05–3.72 g/g, swelling power of 2.85–12.14 mL/g, glucose content of 4.92–7.95 μg/g and cholesterol-adsorbing capacity of 3.89–8.19 mg/g, which were significantly higher than those of dietary fiber extracted by alkaline method, and it had a stronger inhibitory effect on α-amylase (45.43%–66.71%) and pancrelipase (21.50%–36.52%). These results reveal that the dietary fiber of A. cornea var. Li. can be used as a functional food ingredient. This study provides a theoretical basis for further exploring the nutritional value of A. cornea var. Li..