The colloidal titration method for the determination of pectin in tea leaves was investigated and the established method was as follows : The leaves washed with methanol was extracted with 0.5% ammonium oxalate at 80°C. and the obtained extract was made acidic or alkaline and individually treated by the pectin decomposing enzyme. The resulting solutions were titrated with the colloidal method. The content of total pectin was estimated from the difference of these two titers. The content of soluble pectin, which was extracted with water at 20-30°C, was known by the same procedur.
The pectin of other plants also could be determined by this method.