Peroxyl radical scavenging activity of melanoidins in aqueous systems

Melanoidins are widely distributed in our diet, due to home or industrial processing of foods. Until recently, melanoidins were considered to be an inert, brown-coloured polymeric component. However, recent research into their nutritional, physiological, and functional properties has suggested that they have antioxidant properties, and we address this issue in this work. A sensitive procedure for assessing the inhibition of lipid peroxidation by melanoidins in watery media has been developed. Main drawbacks and critical steps of the procedure are discussed. Melanoidins can be classified according to the number of peroxyl radicals trapped per molecule. Coffee and sweet wine melanoidins show higher antioxidant activity than melanoidins isolated from beer. For the first time, a linear relationship between the peroxyl radical scavenging activity and the chromophore residues in the melanoidin skeleton responsible for browning has been established.