Aroma is one of the most important factors for the flavor, taste, and quality of pu-erh tea, and the post-fermentation process has an important influence on the aroma of pu-erh tea. In the present study, the influence of fungi fermentation on the flavor of pu-erh tea was investigated and compared. Volatile compounds from pu-erh tea fermented by four Aspergillus strains, including A. niger, A. oryzae, /1. awamori, and A. glaueus, were extracted and analyzed using ultrasound-assisted extraction-dispersive liquid-liquid microextraction-gas chromatography-mass spectrometry （UAE-DLLME-GC-MS）, and a total of 63 volatile compounds were identified. In comparison with the sun-dried green tea, fermented pu-erh tea contained high levels of methoxyphenolic compounds, such as 1,2,3-trimethoxybenzene, which was the most abundant one. Our results confirmed that the characteristic methoxyphenolic compounds were produced by the activity of Aspergillus during the post-fermentation process, and A. niger and A. awamori were the most important strains for the formation of aroma quality of pu-erh tea.
以黄酮类化合物生物合成过程中的两个关键酶:4-香豆酰辅酶A连接酶(4-coumarate coenzyme A ligase,4CL)和查尔酮合成酶(chalcone synthase,CHS)为工具酶,探讨酶催化组合合成在合成"非天然的天然产物"群(库)中的应用.结果发现在4CL和CHS的共同作用下,仅利用8个简单的有机酸就可以产生包括8个黄酮类似物、16个4-羟基-δ-内酯和1个苄基丙酮共计25个"非天然的天然产物"群,为构建结构多样的小分子化合物群(库)提供方法学参考.
