CHEMISTRY OF PIGMENTS AS INTERMEDIATE OF MELANOIDINS

摘要

Melanoidins, the final products of the Maillard reaction, are brown nitrogen-containing polymers that are difficult to decompose. They have physiologically positive effects such as antioxidative activity, including strong scavenging activity against reactive oxygen species. Many researchers have studied the partial structure of melanoidins in various ways. Tressel's group reported that N-substituted pyrrole, 2-furaldehyde, and N-substituted 2-formylpyrroles, formed in pentose and hexose Maillard reaction systems, were identified as components of extraordinary polycondensation activity. Hofmann identified novel red-brown and red compounds formed in the Maillard reaction system of arginine with glyoxal and furan-2-carboxaldehyde, pentoses and primary amino acids, and hexoses and primary or secondary amino acids. However, above-mentioned compounds have fewer hydrophilic properties, indicating significant differences in the hydrophilic properties of melanoidins. Miura and Gomyo and Gomyo et al. found the formation of colored compounds formed in the Maillard reaction between D-xylose and glycine. Our group has reported identification of the novel blue pigments designated Blue-Mi (Blue-Mi, blue Maillard intermediate-1) and Blue-M2. These blue pigments have a methine proton between two pyrrolopyrrole rings. Blue-Mi and Blue-M2, involving the pyrrolopyrrole structure, were readily changed to a brown polymer. Accordingly, blue pigments are assumed to be generated independently and to be polymerized to form melanoidins. In this paper, we reviewed on the kinetic studies of Blue-Mi, the generation of the other blue compounds in D-xylose-glycine reaction system, similarity between blue compounds and melanoidins, precursors of blue pigments, blue and red pigments from the other Maillard reaction, and the formation of melanoidins from blue pigments.