Optimization of Extraction Process of Xylan from Phyllostachys edulis and Analysis of Its Antioxidant Activity

In order to realize the resource conversion and utilization of bamboo shoot processing waste, the xylan in Phyllostachys edulis was extracted by using the alkali extraction and alcohol precipitation method. The extraction process was optimized by the single factor test and orthogonal test. The physicochemical properties of xylan extrated from Phyllostachys edulis were analyzed by high performance liquid chromatography and Fourier transform infrared spectroscopy. The antioxidant activity in vitro of xylans from Phyllostachys edulis was evaluated by DPPH method and ABTS method. The results showed that: Under the conditions of the extraction time of 3.5 h, the alkali mass concentration of 0.1 g·mL⁻¹, the ratio of solid to liquid being 1∶25 and the extraction temperature of 100℃, the extraction rate of xylan from Phyllostachys edulis was the highest, reaching 20.86%. The monosaccharide composition and FT-IR analysis showed that the xylose may be the main component of xylan from Phyllostachys edulis. The in vitro anti-oxidation test showed that the xylan extracted from Phyllostachys edulis had certain antioxidant activity. When the concentration was 8 mg·mL⁻¹, the scavenging rate of it on the DPPH free radical reached 94.75%, and the IC₅₀ value was 1.0 mg·mL⁻¹. When the concentration was 20 mg·mL⁻¹, the scavenging rate of it on the ABTS free radical was 93.09%, and the IC₅₀ value was 3.85 mg·mL⁻¹.