Abstract:In order to investigate the influence of reaction time on the antioxidant activities of the chitosan oligosaccharide(COS) derivatives,two kinds of COS derivatives were prepared through Maillard reaction by heating COS and xylose with 4 h and 8 h separately(the ratio of-NH2 and C=O was 1∶1),named CX4 and CX8.The absorbance and fluorescence were determined during the reaction.The chitosan oligosaccharide derivatives were characterized by FTIR and their molecular weight was determined by GPC.Their antioxidant activity was investigated by employing various established in vitro systems,such as superoxide/hydroxyl/1,1-diphenyl-2-picrylhydrazyl(DPPH) radicals scavenging and reducing power.The results as flowers:the UV-Vis absorbance at 278 nm had a sharply increase within the first 2 h,which attribute to the Maillard intermediate products;The fluorescence intensity(Ex 343 and Em 435 nm) sharply increased within the first 2 h with a subsequent decrease when heating time increased.Though the Maiilard intermediate products and fluorescence prouducts had not accumulated after 4 h,the derivatives of 8 h showed stronger antioxidant activity compared to the derivatives of 4 h.The antioxidant activity was found to be in the order of CX8>CX4>COS,which indicated that the derivatives had the better antioxidant activity as the reaction processed.
