The fermentation process in tea manufacture

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Abstract
A brief outline was given of the various stages in the manufacture of tea. Oxidase was present in negligible quantities in the tea leaf and the fermentation process was brought about by peroxidase. The 1st stage in fermentation is an uptake of O leading to the oxidation of some as yet unidentified substance, and the production of H2O2. This oxidation was not necessarily an enzymic process. The peroxidase catalysed the oxidation of the tea tannin by H2O2 leading to the production of brown pigments which impart the characteristic color to a tea infusion. Substances grouped as non-tans also underwent oxidation. No evidence was available for the utilization of organic peroxides by peroxidase, and in the fermentation of tea, decomposition of H2O2 by excess catalase inhibited tannin oxidation almost completely. A quantitative method for the estimation of peroxidase in the tea leaf was descr. Peroxidase was inhibited by tea tannin although substances present in the leaf exerted some protective influence against its effect. The theory that these protective substances were protein degradation products, formed during withering, found no support. An outline was given of the changes in peroxidase content of the leaf throughout the various stages in manufacture.

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