Volatile Components of Roasted Green Tea (Hoji-cha)

Part I Carbonyl compounds

Abstract

Volatile components of roasted green tea (hoji-cha) were collected by_vacuum distillation with four steps of low temperature trapping. Some carbonyl compounds were converted to 2, 4-dinitrophenylhydrazones, and the mixtures of them were fractionated by thin layer and gas liquid chromatographies. Among the low boiling carbonyls, acetaldehyde, acetone, propionaldehyde, and isobutylaldehyde were identified, and the presence of 2- or 3-methylbutylaldehyde was also indicated. Furfural, 2-acetylfuran, and 5-ethylfurfural were found in carbonyl compounds of higher boiling temperature, and two unknown carbonyl compounds which seemed to contribute to the roast flavor were also isolated.