Comparison of the Odor Concentrates of Black Tea

Abstract

The volatile compounds of black tea were investigated by using gas chromatography (GC) and gas chromatograph-mass spectrometry (GC-MS), with comparing the methods for preparing odor concentrates. Thirty-nine alcohols, 31 aldehydes, 28 ketones, 17 esters, 7 lactones, 4 phenols, 3 furans and furanones, 29 hydrocarbons and 14 miscellaneous compounds were identified. The odor concentrate prepared by Porapack Q column adsorption method followed by elution with ethyl ether: isopentane (6 : 4) solution had a typical black tea like odor. On the contrary another odor concentrate prepared by simultaneous distillation extraction (SDE) under reduced pressure had a steamed tea leaves like odor and an astringent bitter odor. Flavor index, which was the ratio of the sum of 20 peak areas of group II, i.e., linalool and its four oxides, benzaldehyde, geraniol, etc. to that of 12 peak areas of group I, i.e., hexanal, (Z)-, (E)-2-hexenal, (E, Z)-, (E, E)-2, 4-heptadienal, pentanol, hexanol, (Z)-3-hexenol, etc., was 2.63 for the concentrate prepared by column method and 1.22 for SDE method.