Abstract: Maillard reaction was initiated by heating chitosan oligosaccharide (COS) with glucose at ratios of 1:1, 1:3 and 3:1 of amine group to carbonyl group, respectively. Chitosan oligosaccharide derivatives after 4 hours named CG11-4, CG13-4 and CG31-4 were extracted by alcohol precipitation, and CG13-8, CG31-8 and CG11-8 were obtained after 8 hours. All of the derivatives were characterized by fourier transform infrared (FTIR) spectroscopy and their molecular weight was determined by gel permeation chromatograph (GPC). Their antioxidant properties in vitro were investigated, including superoxide, hydroxyl and 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radicals scavenging capabilities as well as reducing power. The results showed that all of the chitosan oligosaccharide derivatives had strong antioxidant activity when compared with chitosan oligosaccharide. The antioxidant activity was found to be in the order of CG11-8 ＞ CG11-4, CG13-8 ＞ CG13-4, CG31-8 ＞ CG31-4, indicating that the derivatives had the better antioxidant activity as the reaction processed.

Key words: chitosan oligosaccharide, Maillard reaction, reaction time, antioxidant activity