Antioxidant activity of maillard reaction products from lysine-glucose model system as related to optical property and copper (II) binding ability

Maillard reaction (MR) was carried out in L-lysine-D-glucose (Lys-Glu) model system heated at 120°C for 0 to 10 h without pH control. Optical property (UV-Vis absorbance and fluorescence) development of MR was monitored. Antioxidant activity of maillard reaction products (MRPs) was investigated by a series of in vitro tests. The UV-Vis absorbance zero and first-order derivative spectrophotometric was utilized to study the metal-binding property and chelating effect of different fractions of MRPs. MRPs had reducing power, strong free radical-scavenging activity and copper (II)-binding ability. The antioxidant activity of MRPs related well with the UV-Vis absorbance properties of maillard rection. Cu2+-binding to MRPs caused the electronic rearrangement in UV-Vis absorbance intermediates, but had no effect on the chromophore structure in brown polymers. The UV-Vis absorbance compounds were responsible to the reducing power and radical-scavenging activity. The fractions of low molecular weight MRPs showed effective metal-chelating ability. Key words: Maillard reaction products, antioxidant activity, metal-chelating effect, optical properties.