Elucidation of chemical pathways in the maillard reaction by 17O-NMR spectroscopy.

17O-NMR spectroscopy was employed as an innovative method to help understand mechanistic pathways in sugar fragmentation. Elucidation of reaction mechanisms to final Maillard end products was achieved by starting from specific intermediates obtained by synthesis, such as 1-deoxy-D-erythro-hexo-2,3-diulose. This alpha-dicarbonyl was thermally treated in the presence of 17O-enriched water under alkaline conditions. The reaction products were monitored by 17O-NMR spectroscopy and their structures corroborated by complementary techniques. For the first time, evidence is shown for the direct formation of acetic acid from 1-deoxy-D-erythro-hexo-2,3-diulose by an oxidative alpha-dicarbonyl cleavage and incorporation of a 17OH group into the acetic acid released as sugar fragment.