The fermentation process in tea manufacture. 10. The condensation of catechins and its relation to the chemical changes in fermentation

Abstract

An empirical method based on measuring the catechins precipitated by 1% H2SO4 was used to determine the degree of condensation. The condensation index increases in approx. linear fashion with time and temp. of fermentation; this increase continues at times and temps, when the total oxygen uptake is no longer increasing. Values for water-soluble solids and water-soluble catechins in teas receiving varying fermentation, are significantly correlated with each other, and are correlated negatively with the condensation index. About 2/3 of the loss in soluble solids can be accounted for by a tranformation of catechins to high polymers insoluble in water, and by combination of condensation products with leaf protein. The much greater fall in alcohol-soluble solids with increase in the condensation index indicates a combination of condensation products with water-soluble nitrogenous compounds to form complexes soluble in boiling water but insoluble in boiling alcohol.