Effect of Leaf Withering Duration, Maceration types and Aeration Duration on the Quality of Black Tea of Clone TRFK 306 (Kenyan Purple Tea)

Abstract

TRFK 306 is a tea clone rich in anthocyanin giving the leaves a purple coloration and it is of assamica cultivar. It was developed in Kenya by the Tea Research Foundation of Kenya, currently Tea Research Institute and has since been released for commercial utilization. This type of tea clone just like any other tea clone can be processed into any type of tea (green, black, Oolong, white, yellow) depending on choice and preference of the processor. Since the clone was released for commercial utilization in 2011, processors are still not sure how best to process this new tea clone. The current study investigated the effect of processing method, withering and aeration durations on the quality of black tea from TRFK 306. TRFK 6/8 was used as a reference standard because of its proven black tea quality. Orthodox and Cut Tear and Curl (CTC) methods of processing were used in both tea clones. Withering was done at room temperature and varied at an interval of five hours, starting at five hours up to twenty hours. Within each withering regime, aeration was varied at 30 minutes interval from 30-90 minutes. Experienced regular tea tasters did the sensory evaluation by describing the liquor colour, body, strength, briskness and infusion colour then the researchers analysed and interpreted the description using a predetermined scale. Theaflavins, thearubigins, total colour, brightness percentage was analysed using UV spectrophotometer. The results showed that CTC teas had relatively higher black tea quality parameters than the orthodox teas irrespective of the tea clone. Within each processing method, TRFK 306 had better quality than TRFK 6/8. Aeration time had more pronounced effect on quality than withering duration. TRFK 306 processed through CTC and withered for ten hours and aerated for 90 minutes produced the best black tea according to the analysed quality parameters, while TRFK 6/8 produced best tea at twenty hours withering and 90 minutes aeration. For orthodox teas, TRFK 306 produced best tea at twenty hours withering aerated for 90 minutes while TRFK 6/8 produced best tea at fifteen hours withering and 60 minutes aeration. It was concluded that TRFK 306 produces better black tea than TRFK 6/8 based on the chemical parameters analysed.