The Research On The Chemical Characteristics Of The Aroma Of Tea

Aroma is the most important essential of tea quality. This paper studied the volatile constituents of oolong tea, black tea, scented tea and the flower of Edgeworthia chrysantha. The main biochemical constituents and the glycosidically conjugated volatile constituents of oolong tea were also analyzed to reveal the characteristics of the aroma of the teas.The analysis of different grades of tea showed that high quantity of geraniol is the characteristics of Mingbei Shuixian oolong tea. The quantities of nerolidol, cedrol, (Z)-3-hexenyl benzoate, linalool, phenylacetaldehyde, geraniol, 5,6-epoxy-p-ionone, β-ionone and cis jasmone were not only high in the special-quality tea and the first-grade tea, but also positive to the tea quality. The content of free amino acids also showed the obviously positive with the tea quality.Comparing the volatile constituents of Tieguanyin oolong tea by fashionable process with tea by traditional process, the constituents with the aroma of grass note and mild flower odor, e.g., (Z)-3-hexenol, (Z)-3-hexenyl hexanoate, (Z)-3-hexenyl benzoate, (E)-2-hexenyl hexanoate, β-ionone, cis jasmone and nerolidol were tended to form by the light fermentation, while the level of the constituents with the aroma of strong flower odor, e.g., geraniol, linalool, α-farnesene, α-terpineol and linalool oxides were not so high in fashionable-process tea as in the traditional-process tea.The odorless water extraction solutions of oolong tea were hydrolyzed with crude enzyme. The analysis showed that (Z)-3-hexenol, linalool, linalool oxides, methyl salicylate, geraniol, benzyl alcohol and 2-phenylethyl glycosides are the major glycosyl forms of aroma precursors. The glycosides with nerol and nerolidol were also existed in some oolong teas. High content of conjugated geraniol and relatively low contents of benyl alcohol and 2-phenylethanol were the characteristics of oolong tea with Shuixian culvar.For the special production process, the aroma of Lapsang Shouchong was much different from other black teas. The compounds such as longifolene, longicyclene,guaiacol, 4-methylguaiacol, 4-ethylguaiacol, eugenol, etc., which have not been detected in other black teas, were identified in Lapsang Souchong The aroma constituents of tea origin were remarkably higher in smoked Lapsang Souchong than in Lapsang Souchong, while the aroma constituents of the pine terpenoids and the thermal pyrolysis products of the pine wood were inverse. The pine material for smoking was also analyzed for the volatile constituents showing apparent selectivity of the tea leaves to absorb.The scented tea is fumigating with the fresh flowers, so it has an aroma with tea and flower. The main aroma components of the green tea scented with Citrus flower were linalool, methyl anthranilate, nerolidol, farnesol, indole and a-farnesene. The main aroma components of the green tea scented with Osmanthus flower were (3-ionone, a-ionone, dihydro-P-ionone and y-decalactone, which were the characteristics of the aroma of this scented tea. The components between the two scented teas were much different, so it could be concluded that the aroma of the scented tea is due to the aroma of the fresh flower.Edgeworthia chrysantha Lindl. (Thymelaeaceae) is native to China, giving a strong aroma. The major constituents in the flower of Edgeworthia chrysantha were methyl salicylate, benzyl alcohol, 2-phenylethyl acetate, phenylacetaldehyde, 2-phenylethanol, benzaldehyde, methyl benzoate, 6,10,14-trimethylpentadecan-2-one, palmitic acid, ocimene, benzyl acetate, benzyl benzoate and cis jasmone. In the conjugated aroma, benzyl alcohol and 2-phenylethanol were the predominant constituents which were even more than their free forms. The results suggested there are abundant contents of glycosidically conjugated benzyl alcohol and 2-phenylethanol in the flower.