Polymer tea polyphenols (thearubigins = TR) were isolated from a black
tea brew by ultrafiltration. The fraction of relative molecular mass
(M(r)) > 5000 was examined using liquid chromatography. A partial sepa
ration of the TR fraction could be achieved by reversed-phase (RP)-HPL
C and by gel-filtration chromatography, but not a complete separation
into distinct peaks. After hydrolysis, the anthocyanidins delphinidine
and cyanidine and some flavone-C-glycosides were detected. The amount
of cyanidine was 0.26% (in the TR fraction M(r) > 5000). Gallic acid
moieties were also determined after hydrolysis: the amounts were about
2.5% (in the TR fraction mentioned above). An HPLC separation system
from the literature was employed to analyse the stability and extracti
on behaviour of the TR. An extract prepared by a 2-h Soxhlet extractio
n contained only small amounts of TR compared with a tea brew prepared
by a normal 10 min extraction. This is due to incomplete extraction,
not to destruction. Hot-plating the 10-min extract (90-degrees-C, 2 h)
led to a decrease in the peak areas of theaflavin (TF) and other pigm
ents.