Aged fragrance formed during the post-fermentation process of dark tea at an industrial scale

Although aged fragrance is the most outstanding quality characteristic of dark tea, its formation still is not much clear. Thus, the volatiles of Qingzhuan tea (QZT) during the whole post-fermentation process were investigated at an industrial scale. The results showed that most of volatiles increased during pile-fermentation of QZT and weakened during aging storage, but some new volatiles were produced through aging storage. Hexanal, (E)-2hexenal, (E)-2-decenal, 2,6,6-trimethyl-1-cyclohexene-1-carboxaldehyde, heptanal, (E)-2-octenal, (R)-5,6,7,7atetrahydro-4,4,7a-trimethyl-2(4H)-benzofuranone, ionone, 2-heptanone, 3-ethyl-4-methyl-1H-pyrrole-2,5dione, (R,S)-5-ethyl-6-methyl-3-hepten-2-one, cis-5-ethenyltetrahydro-5-trimethyl-2-furanmethanol, and linalool generated by pile-fermentation should be the basic volatiles of aged fragrance in QZT, and 4-(2,4,4-trimethyl-cyclohexa-1,5-dienyl)-but-3-en-2-one, 6-methyl-5-heptene-2-one, safranal, guaiene, trans-2-(2-propynyloxy)-cyclohexanol, nonanal, and 4-(2,6,6-trimethyl-1-cyclohexen-1-yl)-2-butanone formed during aging storage should be the transformed volatiles of aged fragrance in QZT, which together constitute the characteristic components of aged fragrance. Notably, 4-(2,6,6-trimethyl-1-cyclohexen-1-yl)-2-butanone, 6-methyl-5-heptene2-one, and safranal were selected as the key volatiles of QZT. These results contribute to understand better the formation of aged fragrance in dark tea.

Automated summary

The research reveals that most volatiles in dark tea increase during pile-fermentation and decrease during aging storage, with some new volatiles being produced. Specific volatiles generated during pile-fermentation and aging storage are identified as the basic and transformed components of aged fragrance in dark tea, including selected key volatiles.