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

Abstract

Summary 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 ( TF s) and thearubigins ( TR s). Six commercially popular cultivars TV 1, TV 7, TV 9, TV 23, TV 26 and T .3 E /3 of Assam, India, were processed in four different moisture levels (72%, 70%, 68% and 65%). Significant reduction in PPO and PO enzymes, TF s, TRs and theaflavin digallate equivalent was observed with the decrease in moisture content of withered leaf. The TF s (0.83–5.4 mg g −1 ) and TR s (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 TV 1, TV 9 and TV 23 at 70 ± 1% moisture content, while for TV 7 and TV 26, it was 68 ± 1%. Withered leaf moisture content should be carefully chosen to obtain the better quality tea from specific cultivar.