Studies on the “fermentation” of Ceylon tea

Abstract

I. The enzyme prep. was separated into 2 parts: one was soluble in buffer solns. to an increasing extent from pH 5-8, and the other insoluble. The soluble enzyme had a maximum activity in the prepared tea substrate at pH 6-7 and 49[degree], and the optima for the insoluble enzyme were pH 5.4 and 27[degree]. Both enzyme systems showed marked specificity in oxidizing polyphenols with o-hydroxy-groupings only. Addition of H2O2 to either enzyme system increased activity but reduced specificity, p-dihydroxybenzene then being oxidizable. Reaction between enzyme preps. and tea substrate was accompanied by enzymic absorption of O2 but not evolution of CO2. II. The foregoing enzyme systems were comparatively insensitive to KCN. The oxidizing action of the enzymes was further studied, chiefly in vitro. During the oxidation of catechol and tea extract substrates the peroxidase present in the enzyme prep. was not activated, but addition of H2O2 had the same effect as that noted in I. It was possible that o-quinones, in conjunction with H2O2, might form powerful oxidizing agents giving apparent peroxidase activity.