Theaflavins in black tea Comparison of the flavognost and HPLC analysis — preliminary in results

Zusammenfassung

Die photometrische Flavognost-Methode (Diphenylborsaure-(2-aminoethyl)-ester; zur Bestimmung der Theaflavine and eine isokratische RP-HPLC-Methode mit einem Dioden-Array-Detekfor wurden miteinander verglichen. Die Vorteile del Flavognost-Methode liegen in der Schnelligkeit and guten Reproduzierbarkeit. Bei der HPLC-Methode konnten vier verschiedene Theaflavine (Theaflavin, Theaflavin-3-gallat, Theaflavin-3′-gallat and Theaflavin-3,3′-digallat) nach Vorabtrennung mitteh Gelchromatographie quantitativ erfaßt werden. Del Unterschied in der Gesamtmenge an Theaflavinen ist meist um so größer, je mehr Theaflavine vorhandensind. In den meisten Fallen liefert die Flavognost-Methode höhere Werte. Die relativen Anteile der erfaßten Theaflavine sind bei den Tees unterschiedlich, besonders diejenigen an Theaflavin and an Theaflavin-3,3′-digallat.

Summary

The flavognost method and an isocratic reversed-phase HPLC method were compared in determining the theaflavins of black tea. A diode-array-detector was used. The flavognost method is a rapid procedure producing good reproducible results. Using the HPLC method, which is much more time consuming due to the necessity of a pre-separation by gel chromatography, one can determine four different theaflavins (theaflavin, theaflavin-3-gallate, theaflavin 3′-gallate and theaflavin 3,3′-digallate) and their relative amounts. The difference between the results from these two methods normally increases with increasing theaflavin content. In most cases, the values of the flavognost method were considerably higher. Relative amounts of theaflavins are different in teas from different origins, especially those of theaflavin and theaflavin 3,3′-digallate.