New phenolic components and chromatographic profiles of green and fermented teas.
A standardized profiling method based on liquid chromatography with diode array and electrospray ionization mass spectrometric detection (LC-DAD-ESI/MS) was applied to establish the phenolic profiles of 41 green teas and 25 fermented teas. More than 96 phenolic compounds were identified that allowed the teas to be organized into five groups. Epigallocatechin gallate (EGCG) was the major phenolic component of green tea made from mature leaves (group 2), while green tea made from the younger buds and leaves (group 1) contained lower flavonoid concentrations. Partially fermented teas (group 3) contained one-half the EGCG content of the green tea. Fully fermented black teas (group 4) had a trace of EGCG, but contained theaflavins. Highly overfermented black tea (group 5) contained only trace amounts of flavonol glycosides and theaflavins. Over 30 phenolics are new for tea, and this is the first phenolic profile to simultaneously detect C- and O-glycosylated flavonoids, catechins, proanthocyanidins, phenolic acid derivatives, and purine alkaloids.
Lin
Long-Ze
LZ
Food Composition and Methods Development Laboratory, Beltsville Human Nutrition Research Center, Agricultural Research Service, USDA, Building 161, BARC-East, 103000 Baltimore Avenue, Beltsville, Maryland 20705-3000, USA. longze.lin@ars.usda.gov
Chen
Pei
P
Harnly
James M
JM
D044946:Biflavonoids / Q000032:analysis; D002392:Catechin / Q000031:analogs & derivatives / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D005285:Fermentation; D005419:Flavonoids / Q000032:analysis; D006031:Glycosylation; D010636:Phenols / Q000032:analysis*; D021241:Spectrometry, Mass, Electrospray Ionization; D013662:Tea / Q000737:chemistry*
D044946:Biflavonoids; D005419:Flavonoids; D010636:Phenols; D013662:Tea; C056068:theaflavin; D002392:Catechin; C045651:epigallocatechin gallate