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Changes in the specific activities of polyphenol oxidase (PPO), peroxidase (POD), and protease and in the relative amounts of flavan-3-ols for eight genetically derived cultivated teas at various stages of leaf maturity and in four succescive seasons were examined. A series of investigations were carried out to study the cross-reactivity of complex polyphenols and PPO-generated orange-yellow theaflavins, as well as of POD oxidized substrates, producing brown so-called thearubigins during fermented tea processing. From the estimation of five major catechins, PPO activities in young shoots, and theaflavin and thearubigin contents of crushed, torn, and curled (CTC) black teas, the superior variety and flavorful flush characteristics were refined. Notable protein hydrolysis by endogenous protease as measured from free amino acids and formation of tannin-protein complex (browning products) was obtained for cultivar character and product quality. Results showed that process optimization with respect to time, temperature, moisture, and pH maximizes PPO-catalyzed desirable theaflavin pigments, whereas POD-mediated chemical reaction produces dull color.

The formation of thearubigin pigments in prevalent commercial manufacturing systems such as orthodox roll, roll followed by curling, tearing, crushing (CTC), rotorvane combined with CTC and CTC alone was studied in the six Tocklai released clones TV-1, TV-2, TV-8, TV-9, TV-17 and TV-18. The contribution of the pigment composition, especially thearubigins of high, intermediate and low molecular weights as separated by a Sephadex LH 20 column, was examined on the basis of the types of leaves, degree of wither and roll, conditions of fermentation and the temperature and type of drying. It was apparent that the biochemical pathway in the black tea processing could be conveniently followed from the thearubigin formation. Further, the amount of high molecular weight thearubigin could determine the quantity of cream formed in a black tea brew. The thearubigin and concomitant pigments such as theaflavin have distinct organoleptic properties and their variation was reflected in the overall quality of the finished product.

Tocklai Tea Experimental Station, Tocklai, Assam, IndiaVolatile compounds obtained from orthodox black tea and CTC tea were analysed by a g.c.-m.s. method. A difference in the contents of cis-3-hexen01, linalool, linalool oxides, methylsalcylate and geraniol was found between the two types of tea, It was thought that the difference in the contents of volatile compounds might be produced by the individual manufacturing processes. A typical difference in the contents of linalool and geraniol was observed in volatile oils of black teas made from cultivars of v. assarnica and hybrids of assarnica and sinensis. The difference in the volatile compounds in black teas may be related to the genetic variation.

A B S T R A C TBiochemical correlations between volatile flavour constituents (VFC) of C T C bluck teas manufactured jrom fine and coarse plucking of Assam tea and orthodox teas fiom three different altitudes were carried out by GC-MS. 111 general, Jine plucking produced more monoterpenoiils and less nonterpenoids than coarse plucking. The volatile flavour compounds were similar in ull types of tea except that geranoic acid was detected in Darjeeling teus. The different ecosystems of Assam and Darjeeling have been ,found to have u pronounced impact upon aroma concentration. However, major dujerences between the volatiles of teas from the different altitudes at Durjeeliny appear to be not so significant.

Such chemical compositions as the volatile flavor constituents (VFC) in teas are affected by the plucking