The Maillard reaction of inulin with arginine and the antioxidant activity of inulin derivatives

The Maillard reaction was occurred by heating inulin and arginine(the ratio of amine group in inulin and carbonyl group in arginine was 1∶5) at 100 ℃. The products of 10,40 and 70 h were prepared and named IR10,IR40 and IR70,respectively. p H,UV-vis absorbance and fluorescence were determined during Maillard reaction and the derivatives were characterized by FTIR. Their antioxidant activities were evaluated. The results revealed that the p H of the reaction system decreased during Maillard reaction. The UV-vis absorbance at 296 nm increased during the reaction. With 323 nm excited wavelength and 408 nm emission wavelength,the fluorescence intensity increased with the increase of reaction time. Infrared spectrum analysis showed that the Maillard derivatives retained the characteristic absorption peaks of inulin. Three kinds of inulin derivatives had weaker antioxidant activity compared with tea polyphenol,but it was stronger than inulin(its abilities to scavenge DPPH and reducing capacity were almost zero) and the antioxidant activity increased with the increase of reaction time.