AROMA COMPOSITION OF OOLONG TEA AND BLACK TEA BY BREWED EXTRACTION METHOD AND CHARACTERIZING COMPOUNDS OF DARJEELING TEA AROMA

Volatile components of various brewed oolong teas and black teas were analyzed by gas chromatography (GC) and gas chromatography/FTIR spectr ometry/mass spectrometry. The GC pattern of brewed tea extracted by di chloromethane (brewed extract) differs greatly from the GC pattern of the extract prepared by simultaneous steam distillation and extraction method (SDE). The brewed extract includes higher amounts of acids, ar omatic alcohols, and monoterpenediol and lower amounts of monoterpene alcohols than the SDE extract. The Darjeeling brewed extract, which ha s a more complicated aroma pattern, consists of four linalool oxides, linalool, geraniol, hexanoic acid, benzyl alcohol, 2-phenylethanol, tr ans-geranic acid, (E)-2-hexenoic acid, (Z)-3-hexenoic acid, and 2,6-di methyl-3,7-octadiene-2,6-diol. The Darjeeling SDE extract consists of seven main components which include geraniol, linalool, four linalool oxides, and methyl salicylate. The brewed extract of Chan Pin oolong ( red oolong tea), which is similar in aroma to Darjeeling and is made f rom tea leaves infested with green flies (Emposca flavescens) in the s ame way as Darjeeling, contains very high amounts of 2,6-dimethyl-3,7- octadiene-2,6-diol. This compound appears to be the precursor of 3,7-d imethyl-1,5,7-octatrien-3-ol and to be the most important factor in Da rjeeling tea flavor.