Abstract
This study aimed at investigating the influence of different growing conditions in two regions, Timbilil and Kangaita, on the levels of catechins and caffeine. Fresh leaf samples of 60 clones cultivated in both sites were obtained, processed and assayed for levels of caffeine, total and individual catechins using Reverse Phase High Performance Liquid Chromatography (RP-HPLC). The obtained data was subjected to analysis of variance using GENSTAT-C statistical software. Safe for a few clones in the Kangaita site had significantly higher total and individual catechins than those grown in the Timbilil site. A mean epigallocatechin gallate (EGCG) content of 7.9% was observed for Kangaita clones compared to 6.7% in Timbilil. A similar trend was observed for the rest of the individual catechin fractions with a mean epicatechin gallate (ECG) of 3.3% in Kangaita and 2.5% in Timbilil, a mean epigallocatechin (EGC) of 5.2% in Kangaita compared to 5.0% in Timbilil and a mean epicatechin (EC) content of 1.5% in Kangaita compared to 1.4% in Timbilil. Similarly in the total catechins analyses, clones in Kangaita had a mean value of 18.7% compared to 16.2% observed for the Timbilil site clones. However, the Timbilil site clones had significantly high caffeine contents (mean, 4.2%) compared to the Kangaita site clones (mean, 3.9%) although with a few exceptions. Significant interactions (P < 0.05) between clone and region are also observed, suggesting that levels of these biomolecules are bound to differ with the growing region but the extent of variation will vary depending on the clonal genotype. The observed differences in levels of these biologically important biomolecules among the two regions shows the importance of the underlying conditions on the production of tea.
Highlights
Tea is manufactured from the young tender leaves of the plant Camellia sinensis
About 300 g of fresh green tea leaf samples were obtained in triplicates from each of 60 tea cultivars grown in both study sites; Timbilil Estate and Kangaita substation of the Tea Research Institute (TRI)
Kangaita clones had significantly higher (P < 0.05) total catechin content with a mean value of 18.7% compared to 16.2% observed for Timbilil clones
Summary
The tea plants grow mainly in warm (tropical and subtropical) climates and can thrive at an altitude range of 1500 - 2700 m above mean sea levels and require at least 1270 mm of rainfall a year and prefer acidic soils [1]. Tea cultivation in Kenya has expanded tremendously in volume and in the tea growing regions mainly the East (Kiambu, Thika, Muranga, Meru, Nyeri, Kirinyaga and Embu) and West (Kericho, Kisii, Nyamira Bomet, and Nandi) of the Rift valley. There exist small to large differences in climatic and environmental conditions between the different growing regions, which affects yield and quality of the resulting tea products. Catechins and caffeine constitute the most important quality parameters in tea reference. Studies have shown that catechins possess beneficial physiological activities such as antioxidants [6] [7], hypocholesterolemiant [8] [9], anti-atherosclerotic [10], anti-inflammatory [11], and anti-HIV activities [12]
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