Antioxidative Effect of Maillard Reaction Products Using Glucose−Glycine Model System

Using a glucose−glycine system as a Maillard reaction model, the rate of inhibition toward active oxygen by Maillard reaction products (MRP) was investigated by electron spin resonance (ESR). MRP obtained through heating a glucose−glycine mixture for 1 h inhibited more than ca. 90% of active oxygen species existing in the form of hydroxyl radicals ( • OH) in the sample and decreased its inhibition power as heating time increased. Studies have revealed the direct scavenging activity of MRP along with the depression of the Fenton reaction, which is brought about by the strong chelating ability of MRP with Fe 2+ due to the inhibition of • OH. Moreover, the decrease in the inhibition activity toward • OH during the prolonged heating period can be explained by the increase in reducing power of MRP promoting the reduction of Fe 3+ to Fe 2+, and thus, activating the Fenton reaction. The high molecular weight fraction obtained from MRP, because of its stronger metal-chelating capability, inhibited • OH more efficiently than the low molecular weight fraction. In addition, MRP obtained after 1 h of heat treatment exhibited ca. 14% inhibition of superoxide anion (O 2 - ), indicating a lower rate of inhibition compared to that of • OH, which can be explained by the contribution of trace amounts of O 2 - formation during the early stage of glucose−glycine reaction. Keywords: Maillard reaction product; antioxidant; active oxygen species