A STUDY ON ADVANCED MAILLARD REACTION IN HEATED CASEIN SUGAR SOLUTIONS - FLUORESCENCE ACCUMULATION/

The advanced Maillard reaction of lactose/caseinate or glucose/caseina te solutions, heated between 110 and 150 degrees C for 0-30 min, was c haracterized via fluorescence. Fluorescent components were preponderat ely protein-bound with 'free' fluorescence making only 1% of protein-b ound fluorescence. 'Free' fluorescence spectra changed with heating, w hereas protein-bound fluorescence increased only in intensity with hea ting without spectral changes. Glucose/casein and lactose/casein behav ed similarly. The fluorescence spectra corresponded to the typical flu orescence of AGEs (advanced glycosylation end products) that arise in proteins under physiological conditions (maximum excitation and emissi on wavelength of 347 and 415 nm, respectively). Kinetics of fluorescen ce evolution was characterized by a reaction order of 0.5. The apparen t activation energy was about 160 kJ mol(-1) for 'free' fluorescence a nd about 135 kJ mol(-1) for protein-bound fluorescence (the activation energy of the early Maillard reaction is about 100 kJ mol(-1)). Fluor escence evolution was due to many reaction products, as illustrated by HPLC analysis. Peak areas were related to heat intensity. (C) 1998 El sevier Science Ltd. All rights reserved.