ANTIOXIDATIVE ACTIVITY AND SCAVENGING EFFECTS ON ACTIVE OXYGEN OF XYLOSE-LYSINE MAILLARD REACTION-PRODUCTS

The antioxidative activity and scavenging effects on active oxygen of Maillard reaction products (MRP) prepared by heating xylose and lysine (XL) at a molar ratio 1:2 and pH 9.0 for 1-5 h (XL-1 to XL-5) were investigated. The antioxidative activity and browning intensity of XL MRP increased with increasing duration of reaction, but XL-1 and XL-2 MRP showed greater reducing power than other samples (P < 0.05). All XL MRP showed scavenging activity on 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. XL-1, XL-2 and XL-3 MRP exhibited about 50% reduction in absorbance of superoxide. Scavenging effects of XL MRP on DPPH radical and superoxide were markedly decreased after decolorization with Sep-Pak Cartridge C18, indicating that the browning pigment might contain components that can scavenge superoxide or donate hydrogen atoms. The electron paramagnetic resonance spectra indicated that XL MRP had scavenging activity on the hydroxyl radical; this scavenging effect depended on dose (r = 0.99) and increased with increasing duration of reaction. Based on these data, the antioxidative activity of XL MRP may be attributed to the combined effects of reducing power, donation of hydrogen atoms and scavenging of active oxygen.