Kinetics and equilibria of tea infusion. Analysis and partition constants of theaflavins, thearubigins, and caffeine in koonsong broken pekoe

Koonsong Broken Pekoe tea leaf was equilibrated with water at 79.5 and 94.0°C using water: leaf ratios from 25:1 to 100:1. The concentrations of theaflavins, thearubigins, and caffeine were measured in the aqueous extracts. Analysis of the results by a simple two‐phase model gave the concentrations of the three constituents in the original leaf without the necessity for the usual assumption of complete extraction. The theory also yielded the partition constants (distribution coefficients) of the three constituents between swollen leaf and aqueous solution, and the enthalpy changes for their extraction.