Influence of fungal fermentation on the development of volatile compounds in the Puer tea manufacturing process

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.