Abstract
Cacao, persimmon, kaoliang, onion, tamarind and chicory colors are natural brown colorants which are so-called flavonoid type,
but the structures of their major coloring components remain unclear. Since they have similar coloring characteristics, it is difficult to
discriminate each other. In this paper, we develop discrimination analysis among the six colorants mentioned above and caramel color.
Test samples were provided from eight manufactures of their natural brown colorants and Japan Caramel Industrial Association.
The discrimination study was performed focusing on the following color reactions, UV measurements and detection of several
specific components containing the seven colorants: vanillin reagent reaction (qualitative analysis), HPLC-UV detection of
5-hydroxymethylfurfural (5-HMF), GC-FID detection of 4-methylimidazol (4-Mel), UV absorbance of hydrolysate by hydrochloric
acid in butanol, HPLC-UV detection of theobromine, iron (II) sulfate reagent reaction (qualitative analysis), UV absorbance of
supernatant of 80% ethanol solution and detection of sulfer dioxide. The results revealed that combination of these eight tests
enable us to discriminate the seven colorants.
