Chinese scientists have compared the composition of aromatic volatiles forming the flavors of Chinese post-fermented teas — pu-erh, liubao, Ya’an Tibetan tea, jingweifu, fu zhuan and quingzhuan. And the aromas of teas were compared not only among themselves, but also with the aroma of green tea, which was used as a control one. In total, 98 compounds were isolated in the aroma of the studied teas — including 20 aldehydes, eight arenes, six acids, 17 alcohols, 13 ketones, nine esters, nine methoxyphenolics, three alkenes, seven alkanes and six other components, the names of which, apparently, are even more scary to pronounce.
In the course of the study, it was found that the “aromatic map” of pu-erh was dominated by methoxyphenols; Ya’an Tibetan tea — by aldehydes and ketones; liubao — by alcohols and, in particular, cedrol; jingweifu — by ketones and esters. In Hunnan fu zhuan tea there was a lot of aldehyde (E, E) -2,4-heptadienal, as well as geranylacetone, hexahydrofarnesylacetone and damascenone. Well, and in Hubei tea, qingzhuan, there was a lot of hexadecanoic acid and nonanoic acid.
The study also demonstrated that, by the content of aromatic compounds, the post-fermented teas are very different from the green ones and, in addition, they can be divided into two groups; pu-erh with lubao being in one group, and all the rest — in the other. The scientists explain the obvious difference between dark and green teas by the change in aromatic substances in the process of post-fermentation involving microorganisms. And the difference of various dark teas from each other is due to fact that their post-fermentation occurs with the participation of different bacterial and fungal communities.