Seasonal Variations in Catechins and Caffeine Profiles among Tea Cultivars Grown in Kenya

Abstract

Consumption of beverage tea rich in flavonoids is associated with a wide range of health benefits. However, the industry in Kenya has over-relied on black tea whose sustainability is not guaranteed due to glut in the market resulting in low income to farmers. Product characteristics and prices are determined based on the accumulation of the phenolic compounds that are profoundly influenced by environmental and cultivar differences. Profiles of quality-related components were assessed in six new and existing cultivars over three distinct annual seasons. Weather data indicated the wet-cold (April–August) season received the largest amount of precipitation and highest relative humidity, while the hot-dry season (January to March) was the driest with a lower relative humidity. Total catechin (TC) contents were significantly (P less than or equal to0.05) different among the cultivars, seasons, and interactions season x site and cultivar x season x site. Overall, the purple-leafed cultivars had lower TC content compared to the green-leafed teas, whereas teas obtained during the WW season (September–December) had higher levels (14.3%) that are suitable for processing of high-quality tea products. Esterified catechins, EGCG and ECG, formed the major component among individual catechins studied. EGCG was significantly higher during both the CW and WW seasons. Cultivars of ‘China type’ accumulated higher +C content as compared to the ‘Assam type’. EC was highest during the WW season in Timbilil, while in Kangaita, the CW season had slightly higher content. Generally, the Cambod type cv. TRFK 301/1 had the highest caffeine content, while China type cv. TRFK 73/1 had the lowest content. Unlike catechin, caffeine content was highest during the HD season. This information is crucial for interventions on product diversification, value addition and novel marketing strategies in tea.