The antioxidant properties of melanoidins have been partly ascribed to the metal chelating capacity of these compounds. The anionic nature of melanoidins enables them to chelate transition metals .The nitrogen atoms in melanoidins were proposed to be responsible for the chelation of copper ion reported that the ketone and/or hydroxyl groups of the pyranone or pyridone components may act as chelation donor groups in melanoidins. Though no relationship was observed between browning and the iron binding ability of melanoidins in model systems showed that the zinc-chelating activity of brewed coffee decreased as the intensity of the roasting increased, suggesting that the chromophoric groups of melanoidins may not be the main co-ordination sites for metal complexation, but the metal chelating activity of melanoidins may be due to other, as yet unknown, structures of them.