Free radical scavenging capacity of Maillard reaction products as related to colour and fluorescence

The free radical scavenging activity of Maillard reaction products (MRPs) p roduced by heating glucose or lactose with lysine, alanine or glycine was e stimated directly by means of a 2,2-diphenyl-1-picrylhydrazyl radical (DPPH ) method. Model systems of sugar (lactose and glucose) and amino acid (alan ine, glycine, and lysine) were heated without pH control at 100 degreesC up to 24 h. Fluorescence (347 and 415 nm), browning (absorbance at 420 nm), c olour parameters in the CIELab scale, and free radical scavenging activity were determined. Browning is not directly related to the free radical scave nging properties of MRPs formed at prolonged heating conditions. This study shows that fluorescence measurement of heated sugar/amino acid systems is more effective than browning to follow the formation of MRPs with free radi cal scavenging activities. This approach could be applied to optimise the f ormation of natural antioxidants during food processing where browning is n ot desirable for consumers. (C) 2000 Elsevier Science Ltd. All rights reser ved.