Characterization of food melanoidin.

Melanoidin is a colored substance which is generally found in food system. Its formation mechanism has been mostly studied by model systems which consist of reducing sugar and amino acid. The author proposes a few methods to characterize melanoidin in food system. Electrofocusing profile of soy sauce melanoidin was found to be similar to that of the model melanoidin. Fe(‡U) chelating Sepharose 6B column chromatography of soy gave a proof of the presence of polyphenolic-type melanoidin which was adsorbed to the Fe (II) -column with strong affinity. Coffee melanoidin was adsorbed to the Cu (II) -column with stronger affinity than soy sauce melanoidin. Food melanoidins were categorized into 3 groups by microbial degradation using Coriolus versicolor. Model melanoidin, soy sauce and cane, molasses were characterized by reduction of color intensity by more than 50%; cocoa was characterized by adsorption of the melanoidin to the cell surface; coffee was almost stable against the microbial degradation.