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...
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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.
Abstract: To investigate the chemical constituents of the roots of Polygala wattersii Hance, the separation and purification were performed by solvent extraction and repeated column chromatography (CC) on silica ge...
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Abstract: To investigate the chemical constituents of the roots of Polygala wattersii Hance, the separation and purification were performed by solvent extraction and repeated column chromatography (CC) on silica gel, Sephadex LH-20 and macroporous resin D101, preparative TLC and semi-preparative HPLC. The structures were identified by spectroscopic analysis and comparison of their 1H and 13C NMR data with those reported in literatures. Twenty-three known compounds, including eleven xanthones (1-11), nine sugar esters (12-20), two triterpenoid saponins (21 and 22) and one phenylpropanoid (23) were isolated and their structures were identified as 1,3-dihydroxyxanthone (1), 1-hydroxy-3-methoxyxanthone (2), 1,3-dihydroxy-2-methoxyxanthone (3), 1,3,7-trihydroxy-2- methoxyxanthone (4), 1,3,6-trihydroxy-2,7-dimethoxyxanthone (5), 1,6,7-trihydroxy-2,3-dimethoxyxanthone (6), 1,7-dihydroxy- 2,3-methylenedioxyxanthone (7), 1,7-dimethoxyxanthone (8), 1,2,3-trimethoxyxanthone (9), 1-methoxy-2,3-methylenedioxyxanthone (10), 6-hydroxy-0-methoxy-2,3-methylenedioxyxanthone (11), 3'-O-feruloyl-6-O-acetyl sucrose (12), arillatose B (13), sibricose A5 (14), sibricose A6 (15), 3',6-di-O-sinapoyl sucrose (16), tenufoliside A (17), 3'-O-3,4,5-trimethoxycinnamoyl-6-O-p-methoxybenzoyl sucrose (18), glomeratose A (19), 1-O-p-coumaroyl-D-glucopyranose (20), bayogenin-3-O-glucoside (21), tenufolin (22), and sinapic acid (23). Among them, compounds 2 and 12 were obtained from genus Polygala for the first time, and except compound 16, all others were isolated from this species for the first time.
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