Characterization of Tannase Activity on Tea Extracts

Assay of tannase activity was performed directly, using extracts of black tea leaf, by a pH stat method at the pH optimum of the enzyme (6.0). Reaction rates were calculated from the initial rates of the volume of titrant vs. time plots, and activity was expressed as μmoles/min. The enzyme was unstable to pH levels above 6.0 and temperatures above 40°C. Optimum temperature was 35°C. Using saturating amounts of enzyme, the pH stat was also used to determine total hydrolyzable gallate for kinetic studies and to determine the effect of gallated polyphenols on loss of solids in instant tea processing.