Abstract
The purpose of this study was to characterize food melanoidin. Model melanoidin was prepared from glucose and amino acid, and the following methods were found to be available for the characterization of model and food melanoidins: electrofocusing, metal-chelating affinity chromatography, lectin affinity chromatography, oxidative and reductive conditions, preparative conditions, nutritional balance study in rats, and microbiological discoloration of brown pigments. The major precursors of fish sauce melanoidin and onion sauté melanoidin were found to be of the sugar type. Browning of freeze-dried tofu was caused by reaction between protein and unsaturated carbonyl compounds formed through autoxidation of lipids. The brown-colored materials were ether-soluble, weakly acidic, and reductone. Coffee melanoidin was formed by the Maillard reaction of sugar and amino acid to protein, involving oxidative degradation and polymerization of phenolic compounds such as chlorogenic acid and ferulic acid. Streptomyces werraensis TT4 (S), Paecilomyces canadensis NC-1 (P), and Coriolus versicolor IFO30340 (C) were cultured with browned foods and various types of model colorants. The colorants that exceeded the 50% decolorization rate for each microbe included P decolorized phenolic colorants such as coffee and black tea, C decolorized sugar-type model melanoidins, waste molasses, miso and soy sauce, and S decolorized caramel and sugar-type model melanoidins.
