Identification of potent aroma components in brewed black teas

The aroma concentrate from brewed black tea (Darjeeling) were obtained by a Porapak Q column adsorption method followed by elution with diethyl ether : isopentane (4 : l)solution. Twenty-three peaks with the higher flavor-dilution (FD)-factor, which significantly contribute to black tea aroma, were found by aroma extract dilution analysis (AEDA) of the aroma concentrate. Twenty-eight components were identified by GC-MS and MDGC. Linalool and vanillin were found to be the most potent aroma components. Phenylacetaldehyde, methyl salicylate, hexanoic acid, geraniol, guaiacol, (Z)-3-hexenoic acid and heptanoic acid were also important aroma components. Of all the aroma components, 5-ethyl-2,3-dimethylpyrazine, 2-acetyl-3-methylpyrazine, 2-hydroxy-3-methyl-2-cyclopenten-1-one and 4-vinylguaiacol have been found in black tea for the first time. Besides the FD-factor of Darjeeling black tea, those of Assam and Uva black teas were also measured. Twenty-three peaks identified in Darjeeling black tea were similarly confirmed in Assam and Uva black teas, and accordingly the difference of overall aroma of three kinds of black teas were found to be caused by different concentration of the potent aroma components.