Grade Tea Research Articles

Studies on the Colored Components in Black Tea Infusion

By using Sephadex LH-20 column chromatography in aqueous acetone, the colored components in black tea infusion were separated into nine groups.Among these groups the early eluted group (1-4) consisted of high polymerized colored substances. Group 5 consisted of thearubigins and the colored components in group 7-9 were theaflavins.From the chromatograms of two different grade teas (black tea of high grade and low grade), it was observed that the chromatogram of the former had a well-defined thearubigin peak and theaflavin peaks and that of the latter had noticeably large peaks of high polymerized colored compounds (group 1-2) and theaflavin peaks were not recognized, definitely.

Study on the Brewing Conditions of Black Tea

The extracted amount of the tannin, soluble nitrogen and soluble matter and the concentration of the tea infusion were examined under the different brewing conditions of black. tea.During the period of brewing, the hotter the water, the more the extracted tannin, soluble nitrogen and soluble matter from the leaf. And the longer the period of brewing, the more the extracted soluble substances.The tea infusions grew stronger liquors by hotter and longer brewing, but the liquor of low grade tea became duller in colour.As the results of these experiments, the suitable brewing conditions were supposed to be about 90°C.: 5 minutes or 100°C.: 2-3 minutes.