Identification of a novel blue pigment as a melanoidin intermediate in the D-xylose-glycine reaction system.

Some blue pigments were formed in the D-xylose (1 M)-glycine (0.1 M) reaction system. A novel blue pigment, designated as Blue-M2 (blue Maillard intermediate-2), was identified as 5-[1,4-dicarboxymethyl-5-(2,3-dihydroxypropyl)-1,4-dihydropyrrolo[3,2-b]pyrrole-2-ylmethylene]-1,4-dicarboxymethyl-2-{5-[N-carboxymethyl(2,3,4-trihydroxytetrahydrofuran-2-yl)methylamino]-2-hydroxymethyl-4-(1,2,3-trihydroxypropyl)tetrahydrofuran-3-yl}-4,5-dihydropyrrolo-[3,2-b]pyrrole-1-ium. Blue-M2 is presumed to have been generated by the reaction between Blue-M1, which was identified as the major blue pigment in a previous paper (Hayase et al., Biosci. Biotechnol. Biochem., 63, 1512-1514 (1999)), and di-D-xyluloseglycine. Blue pigments are important Maillard reaction intermediates through the formation of melanoidins.