Control Formation\nof Furans and Pyrazines Resulting\nfrom Dual Glycation Sites in <i>N</i><sub>α</sub>,<i>N</i><sub>ε</sub>‑Di(1-deoxy‑d‑xylulos-1-yl)lysine\nvia Elevating Thermal Degradation Temperatu

Lysine (Lys) glycated by xylose (Xyl) at α-NH<sub>2</sub> [<i>N</i><sub>α</sub>(1-deoxy-D-xylulos-1-yl)lysine\n(<i>N</i><sub>α</sub>-Xyl-Lys ARP)] or ε-NH<sub>2</sub> [<i>N</i><sub>ε</sub>-(1-deoxy-D-xylulos-1-yl)lysine\n(<i>N</i><sub>ε</sub>-Xyl-Lys ARP)] significantly\nimpacted the thermal degradation pathways of Amadori rearrangement\nproducts (ARPs). <i>N</i><sub>α</sub>-Xyl-Lys ARP\nwas found to undergo retro-aldolization on the sugar fragment more\nreadily to form glyoxal/methylglyoxal than <i>N</i><sub>ε</sub>-Xyl-Lys ARP. Furans and pyrazines formation during\nthe degradation of the diglycated lysine [<i>N</i><sub>α</sub>,<i>N</i><sub>ε</sub>-di(1-deoxy-d-xylulos-1-yl)lysine\n(<i>N</i><sub>α</sub><i>,N</i><sub>ε</sub>-di-Xyl-Lys ARP)] was delayed at 120 °C relative to <i>N</i><sub>ε</sub>-Xyl-Lys ARP. This was attributed to\nthe complex degradation of <i>N</i><sub>α</sub><i>,N</i><sub>ε</sub>-di-Xyl-Lys ARP, which slowed the substantial\nformation of deoxypentosones and the effective release of Lys. At\n140 °C, the dual glycated <i>N</i><sub>α</sub><i>,N</i><sub>ε</sub>-di-Xyl-Lys ARP was more conducive\nto promoting the redistribution of electrons and facilitating molecular\nrearrangement. This accelerated the efficient decomposition of dual\nglycated groups in <i>N</i><sub>α</sub><i>,N</i><sub>ε</sub>-di-Xyl-Lys ARP and enabled glyoxal to actively\nparticipate in Strecker degradation. Thus, the production of furans\nand pyrazines was substantially increased, and the variety of pyrazines\nwas expanded from three types to eight types. An appropriate increase\nto pH 7.5 effectively avoided the overprotonation of hydroxyl and\namino groups (pH 5.5), simultaneously enhancing furans and pyrazines\nyield while minimizing the formation of pyridines under alkaline conditions.