Puer tea is a unique Chinese fermented tea with natural flora manufactured in Yunnan Province of China. Very complex changes take place to form special quality and flavor characteristics in Puer tea due to the coordination of microbial metabolic action and natural oxidation. This paper investigates the isolation and identification of fungi responsible for the fermentation and the development of main volatile compounds of Puer tea during the fermentation process by means of GC/MS. Aldehydes and ketones in parched green tea (raw material) with low boiling‐points decreased significantly, while the amount of terpene alcohols – such as linalool and linalool oxides, methoxybenzene and derivatives, and indole – increased remarkably from the parched green tea to the Puer tea product after the manufacturing process. Degradation caused by heat and microbial growth at the piling stage likely played a key role in the generation of these compounds that contributed to the aromatic characteristics of Puer tea. It is hypothesized that the fungus Aspergillus niger plays a decisive role in the development of the volatile compounds.

Fuzhuan brick-tea is a popular fermented Chinese dark tea because of its typical fungal aroma. Fungal growth during the production process is the key step in achieving the unique colour, aroma and taste of Fuzhuan brick-tea. To further understand the generation of the characteristic aroma, changes in the main volatile compounds of Fuzhuan brick-tea during the fungal growth stage were studied by gas chromatography/mass spectrophotometry. The results showed that the content of volatile compounds, especially aldehyde compounds with stale aroma such as (E)-2-pentenal, (E)-2-hexenal, 1-penten-3-ol, (E, E)-2,4-heptadienal and (E, Z)-2,4-heptadienal, increased significantly in fermented tea samples. The concentration of terpene alcohols with flower aroma also increased notably during the fermentation process. The compounds with stale and flower aromas in combination with some volatile components of the raw material contributed to the characteristic 'fungal/flower' aroma of Fuzhuan brick-tea. Microbial metabolism during the fermentation process probably played the key role in the generation of characteristic aromatic compounds of Fuzhuan brick-tea.