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Survey of catechins, gallic acid, and methylxanthines in...

Summary citation from AGRICOLA, the online catalog of the National Agricultural Library (NAL)
 

Survey of catechins, gallic acid, and methylxanthines in green, oolong, pu-erh, and black teas.

An isocratic HPLC procedure was developed for simultaneous determination of six catechins, gallic acid, and three methylxanthines in tea water extract. A baseline separation was achieved on a Cosmosil C18-MS packed column with a solvent mixture of methanol/doubly distilled water/formic acid (19.5:80.2:0.3, v/v/v) as mobile phase. A gradient HPLC procedure was also provided for the separation of these tea components. The contents of catechins, gallic acid, and methylxanthines have been measured in infusions of a range of green tea, oolong tea, and pu-erh tea products sold and consumed in the China, Japan, and Taiwan. When 15 Chinese green tea and 13 Japanese green tea products were analyzed by the HPLC method, the mean levels of the total catechins, (-)-epigallocatechin 3-gallate, (+)-catechin, and caffeine were found to be very similar in these two groups, but other minor catechins such as (-)-epigallocatechin, (-)-epicatechin, and (-)-gallocatechin 3-gallate were found to be higher in Japanese green tea products, whereas (-)-epicatechin 3-gallate, gallic acid, theophylline, and theobromine were found to be higher in Chinese green tea products. Oolong tea products possessed lower levels of catechins, whereas pu-erh tea products contained negligible amounts of these constituents. The new HPLC method is rapid, reliable, and reproducible and should be highly recommended to tea industries for routine analysis of commercial tea samples.

Journal Title: Journal of agricultural and food chemistry.
Journal Volume/Issue: Sept 1998. v. 46 (9)
Main Author: Lin, J.K.
Other Authors: Lin, C.L., Liang, Y.C., Lin-Shiau, S., Juan, I.M.
Format: Article
Language: English
Subjects: tea
fermented foods
fermentation
gallic acid
xanthines
flavanols
chemical composition
food analysis
separation
rapid methods
high performance liquid chromatography
extracts
China
Japan
Taiwan
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