Studies on the Free Radical in Amino-Carbonyl Reaction

A relatively stable free radical signal was detected by ESR spectroscopy in the mela-noidin prepared from glycine and glucose. All attempts made to remove molecular oxygen from the melanoidin matrix resulted in a reversible increase in signal height without changing the line width and g-value of central resonance. Nitric oxide, a well-known quenching agent for radicals, retarded the reaction ensuing in disappearance of furfurals and deposition of a new compound. These results allowed to envisage a steps of free radical formation involved in the amino-carbonyl reaction and also nature of the free radical species.