Optimisation of withered leaf moisture during the manufacture of black tea based upon theaflavins fractions



A study was conducted to see the effect of different moisture content of withered leaf on the activity of oxidative enzymes polyphenoloxidase (PPO) and peroxidase (PO) and on the formation of theaflavins (TFs) and thearubigins (TRs). Six commercially popular cultivars TV1, TV7, TV9, TV23, TV26 and T.3E/3 of Assam, India, were processed in four different moisture levels (72%, 70%, 68% and 65%). Significant reduction in PPO and PO enzymes, TFs, TRs and theaflavin digallate equivalent was observed with the decrease in moisture content of withered leaf. The TFs (0.83–5.4 mg g−1) and TRs (23–107 mg g−1) fractions were lowest at moisture level 65 ± 1%. Of the six cultivars studied, better quality of black tea was obtained for cultivar TV1, TV9 and TV23 at 70 ± 1% moisture content, while for TV7 and TV26, it was 68 ± 1%. Withered leaf moisture content should be carefully chosen to obtain the better quality tea from specific cultivar.