关键词: 六安瓜片, 茶叶香气, 特征香气成分, 茶叶等级

Abstract: In order to thoroughly investigate aroma volatile compositions of the historically famous Lu'an Guapian tea, and evaluate their differences among the four quality grades: the super grade, the first grade, the second grade and the third grade, the tea samples processed in the internal mountains of Lu'an, Anhui Province, China were collected and analyzed. Essential oils from each of the four grades of tea samples were extracted by simultaneous distillation extraction (SDE), and then analyzed by gas chromatography coupled with mass spectrometry (GC-MS). The volatile aroma constituents were identified by comparison of mass spectra and retention times with those of authentic standards, and quantified by their relative abundances to the internal standard, ethyl decanoate. A total of 96 aromatic compounds were identified from the four grade teas, including 20 alcohols, 18 esters, 17 alkenes, 16 aldehydes, 12 ketones, 7 heterocyclic compounds and a few organic acids. The major aromatic constituents were linalool, geraniol, cis-nerolidol, β-ionone, cis-3-hexenyl hexanoate, benzaldehyde, n-hexadecanoic acid, linalool oxide I, β-cyclocitral, α-ionone, Z-3-hexen-1-ol, heptanal and nonanal. The numbers and total abundances relative to the internal standard of these identified aromatic constituents from the super grade, the 1st grade, the 2nd grade and the 3rd grade were 79/695.94, 60/579.90, 55/541.69, and 47/268.50, respectively. Both the numbers and total abundances were positively related to the tea quality. The tea quality was positively correlated with the number and abundance of aromatic compounds. Conversely, the major aroma components, linalool, cis-nerolidol, α-ionone, β-ionone and cis-3-hexenyl hexanoate, were significantly reduced with the tea quality grades decreased. It was concluded that the high contents of diversified aromatic constituents, especially their major identified constituents in the Lu'an Guapian teas are probably responsible for its overall pleasant and refreshing scent and flavor. However, there were still significant differences in both aromatic constituents and their total abundances, thus also the fragrances, among the four quality grades.

Key words: Lu'an Guapian tea, tea aroma, characteristic aromatic constituents, tea quality grade