REACTION CONDITIONS INFLUENCE THE ELEMENTARY COMPOSITION AND METAL CHELATING AFFINITY OF NONDIALYZABLE MODEL MAILLARD REACTION-PRODUCTS

Nondialyzable glucose-lysine (Glu-Lys) and fructose-lysine (Fru-Lys) M aillard reaction products (MRPs) were synthesized by reacting 0.8 M L- lysine with 0.8M D-glucose or 0.8 M D-fructose using 14 different comb inations of reaction time, temperature, initial pH, and initial water activity. The extent of browning in each reaction was monitored by UV- vis absorbance spectra, absorbance at 420 nm, and the yield of nondial yzable MRPs. Crude MRPs were fractionated further by immobilized metal affinity chromatography. Although the relative concentration and the number of unidentified intermediate compounds present in Glu-Lys and F ru-Lys MRP mixtures varied considerably, two principal components for both Glu-Lys and Fru-Lys MRP mixtures with molecular masses of approxi mately 5700 and 12 400 Da were identified by MALDI-MS. Elementary comp osition and copper chelating affinity of crude and fractionated MRPs w ere greatly influenced by type of reactant sugar and reaction conditio ns used for synthesis. Glucose, in general, produced MRPs with relativ ely higher copper chelating affinity, possessing higher percentages of carbon and lesser percentages of nitrogen compared to counterpart Fru -Lys MRPs.