The fermentation process in tea manufacture

IN Part III of this series [Roberts, 1939, 2] evidence was presented in favour of the view that the primary stage in the oxidative processes in tea fermentation was an enzymic oxidation of ascorbic acid. There was considerable experimental support for this view and the conception was in accord with Huszak's [1937] findings on the role of ascorbic acid oxidase in peroxidase plants. A mechanism for the fermentation process in tea was put forward, based on the assumption that ascorbic acid was the oxygen carrier in both normal respiration of the tea leaf and in the fermentation process. This mechanism proved quite satisfactorv in explaining the broad outlines of the process but subsequent work has revealed several inconsistencies which make the original mechanism untenable. These inconsistencies are considered below.