# Recent Advances in Volatiles of Teas
## 2 Aromatic Volatile Compounds in Various Kinds of Teas
### Variation of Aromatic Volatiles between Various Kinds of Tea
(Z)-1,5-octaiden-3-one (metallic), 4-methoxy-2-methyl-2-butanethiol (meaty), 4-mercaptoethanol-4-methyl-2-pentanone (meaty), (\(E\),\(E\))-2,4-decadien (fatty), \(\beta\)-damascenone (honey-like), \(\beta\)-damascone (honey-like), indole (animal-like) and (\(Z\))-methyl jasmonate (floral) are the most important odorants of Japanese steamed green tea [28; 29]. Geraniol (rose floral), linalool (sweet floral), linalool oxides (sweet floral), indole (animal-like), dihydroactinidiolide (sweet), _cis_-jasmone (jasmine floral), 6-chloroinodide (indole like), coumarin (sweet), methyl jasmonate (floral), trans-geranylacetone (fruity), phytol (sweet), 5,6-epoxy-\(\beta\)-ionone (rose floral) and phenylethyl alcohol (floral) are identified as various aroma-active compounds of green tea beverages prepared using steamed green tea [30; 31]. However, Chinese roasted green teas contain high amounts of pyrazine (nutty), pyrrole (nutty),4-hydroxy-2,5-dimethyl-3(\(2H\))-furanone (sweet strawberry), 3-hydroxy-4,5-dimethyl-2(\(5H\))-furanone (sweet strawberry), coumarin (sweet), vanillin (vanilla-like), geraniol (rose floral), (\(E\))-isoeugenol (clove like) and 2-methoxyphenol (smoky). They have a high flavor dilution (FD) factor, which is defined as the highest dilution in which the tested odorant is perceived by trained panelists. (\(E\))-isoeugenol (clove like) content is closely related to the green tea manufacturing process [32]. Moreover, 4-mercaptoethanol-4-methyl-2-pentanone, a roasted odorant contributing to the aroma of roasted green tea, increased with the increasing roasting temperature [33]. During the storage of green tea, 2-butyl-2-octenal (fruity) increased with time [34]. Oolong tea is a semi-fermented tea with a floral aroma. The major volatiles isolated from oolong tea were _cis_-jasmone (jasmine floral), \(\beta\)-ionone (rose floral), nerolidol (woody), jasmine-lactone (jasmine floral), methyl jasmonate (jasmine floral), indole (animal like), linalool and its derives (sweet floral) and geraniol (rose floral) [35; 36]. These odorants are formed from precursors, such as (\(S\))-linalyl \(\beta\)-primeveroside, _cis_- and _trans_-linalool 3,7-oxides 6-O-\(\beta\)-d-apiofuranosyl-\(\beta\)-glucopyranoside, (\(Z\))-3-hexenyl \(\beta\)-d-glucopyranoside, methyl salicylate 6-O-\(\beta\)-d-xylopyranosyl-\(\beta\)-d-glucopyranoside and 8-hydroxygeranyl-\(\beta\)-primeveroside [12; 37]. Microorganisms, such as fungus, are involved in the post-fermentation of Pu-erh tea processing, resulting in a moldy or musty smell. The major volatiles in Pu-erh tea included methoxyphenolic compounds, hydrocarbons and alcohol compounds, such as 1,2,3-trimethoxybenzene (storage musty), 1,2,4-trimethoxybenzene (storage musty), 2,6,10,14-tetramethyl-pentadecane (unknown), linalool and its oxides (sweet floral), \(\alpha\)-terpineol (illac), and phytol (sweet) [38]. The volatile composition of Pu-erh tea depends on the extraction method. Head space solid-phase microextraction (HS-SPME) was suitable for testing Pu-erh tea flavor [39; 40]. White tea is a special tea processed using shoots with abundant leaf trichomes. There is abundant essential oil in the trichome joint by which the trichome is attached to the leaf lower epidermis [41], and so, white tea has high levels of volatiles, especially hexenal (green grassy odor) and (\(E\))-hexenol (green grassy odor) [27]. The volatile composition is differentiated between various kinds of tea owing to the differences in cultivar and processing method, resulting in variation of aromatic characteristics. Table 1 lists the top ten volatiles in five kinds of tea. The different kinds of tea can be partially classified by cluster analysis using the index of individual catechins and volatile components [27].