Abstract:Taking xylan (Xyl) and ferric chloride as substrates, the effects of the mass ratio of Xyl to sodium citrate, reaction temperature and pH on yield rate was investigated by single factor test. Preparation technology of xylan polysaccharides iron complex (XPC) was optimized by response surface methodology. The preliminary structure characterization of Xyl and XPC was performed by infrared spectroscopy and X-ray diffraction. The DPPH free radical, superoxide anion, hydroxyl radical and reducing power of XPC was also studied. The results showed that the optimum preparation conditions were as follows: the mass ratio of Xyl to sodium citrate of 3:1, reaction temperature of 70 ℃ and pH of 8.0. Under the optimal conditions, the yield of XPC was 66.59%, and the iron content was 22.57%. Infrared spectroscopy and X-ray diffraction confirmed that iron (III) ions were successfully chelated with Xyl without destroying its basic framework. The maximum scavenging rates of XPC to DPPH, hydroxyl and superoxide anion radicals were 73.44%, 30.95% and 22.72%, respectively. Compared with Xyl, the antioxidant activities of XPC significantly increased.