Catechins depletion patterns in relation to theaflavin and thearubigins formation

The determination of the depletion pattern of catechins in black tea processing is important in achieving optimum tea quality. This study investigated catechins (unoxidised di- and trihydroxylated) depletion patterns in relation to theaflavin and thearubigin formation. It was during the process of green leaf fermentation at selected temperature and time combinations. The tea leaves were obtained from three clones (6/8, 303/577 and 311/287) within the Tea Research Foundation of Kenya. The results were showed that unequal depletion rates of di- and trihydroxylated catechins led to a decline in total theaflavin and an increase in thearubigins levels. An equitable decline in both groups of catechins corresponded to a subsequent rise in theaflavins content. The decline in the catechins levels was much faster at higher temperatures resulting in a shorter fermentation time to achieve a peak of the theaflavins content. Clone 311/287 had the highest mean theaflavins content (26.99 μmol/g) and the least mean percent thearubigins (15.02%) level. Theaflavins content correlated positively with liquor brightness determined by a spectrophotometer and tea tasters (r = 0.7221, p < .0001). The thearubigins content was however found to relate negatively with liquor brightness. It was concluded that the experimental conditions tested form a good basis for clonal specific processing conditions that can be utilised in manufacturing quality black tea.