Factors affecting theaflavin values of black tea in South Africa: A preliminary analysis

Abstract

The highest theaflavin (TF) contents associated with five tea clones grown in the Eastern Transvaal were encountered in the manufactured tea from ‘MT 12’ followed by ‘SFS 204’, with ‘Veld 35’ and ‘Veld 43’ having the lowest values. TF contents of the latter two clones were not significantly different for hand-plucked as compared with machine-plucked tea, whereas with the other three clones hand-plucking resulted in higher TF values. A fermentation period of 90 as compared with 30 min increased TF content in ‘MT 12’. Insufficient or no withering had a detrimental effect on the TF's of black tea when the leaves were processed on the same day of plucking, unless the leaves were left in the sun for 5 h, after which the highest TF value was obtained. Over-withering for 2 days gave the lowest TF concentration, probably as a result of a lowering of polyphenol oxidase activity. The possibility that this may affect tea flavour is discussed.