EFFECTOF LEVEL OF CHEMICAL WITHER AND DURATION OF FERMENTATION ON BIOCHEMICAL COMPOSITION OF MADE TEA

Abstract

Aseries of withering and fermentation experiments in black tea processingwere conducted in Environmentally ControlledManufacturing (ECM) system. Three different hygrometric conditions (i.e. T1, T2 and T3) during withering and five different fermenting times during fermentation were maintained to assess the variation in quality components of black tea. To prepare the samples fresh tea leaves of clones TV1 and TV26 were collected fromthe experimental garden of Tea Research Association, Jorhat. Composition of five major catechins i.e. EGC, +C, EC, EGCG and ECG in fresh (F) as well as in withered (W) leaf and theaflavins (TF), thearubigins (TR) and its fractions, total color (TC), brightness (B) and volatile flavor components (VFC) in black tea were estimated using High Performance Liquid Chromatography (HPLC), Gas Liquid Chromatography (GLC) and UV/Vis spectrophotometer. In this set of experiment total withering time was maintained 12hrs, where the moisture loss in the initial hours was restricted by manipulating the wet bulb depression (WBD). Under the leastWBD (T3) the chemical changes (chemical withering) was most favorable fromquality point of view. Fermentation time 50min was found better for obtaining brighter tea in TV1 whereas for TV26 itwas 70min. Itwas observed that Flavour Index (FI) in clone TV1 was higher in treatment T3 while for clone TV26 it was T1