Catechins (flavan-3-ols) are polyphenolic plant secondary metabolites that have been strongly associated with a wide variety of beneficial health effects in vitro, in vivo and clinically. This study reports findings on the content of catechins in tea seed oil (TSO) extracted by Soxhlet extraction from seeds of different clones of Kenyan tea. Extraction of catechins from the crude oils was achieved by sequential liquid-liquid extraction (LLE) using methanol and quantified by reverse phase High Performance Liquid Chromatography (RP-HPLC). Results obtained revealed that all the crude test oils contained catechins, with oils extracted from clones TRFK K-Purple and GW-Ejulu having the highest total catechin content of 9.8 ± 0.25 and 9.0 ± 0.83 (×10 −3 % flavonoids) respectively. Statistically significant differences (p < 0.05) were evident in the total catechin contents of crude oils extracted from tea seeds with those extracted from corn, sunflower and soybean seeds. Moreover, clonal variations were evident, as the total catechin contents of oils extracted from clones TRFK K-Purple and GW-Ejulu were statistically different (p < 0.05) from those extracted from clones TRFK 301/3, TRFK 301/4, TRFK 301/5, TRFK 306, TRFK 91/1 and TRFCA SFS 150. Thus, the current findings strongly suggest that oils from seeds of Kenyan tea cultivars can be a potential source of potent natural antioxidants.
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. * Corresponding author.A. M. Mutuku et al. 563
A study was carried out to quantitatively estimate the L-theanine content in 19 teas commercially available in the Kenyan market by High Performance Liquid Chromatography (HPLC). The test tea samples analyzed were green (n = 4), black (n = 8) and flavored (n = 7) teas from different origins viz., Kenya (n = 4), Uganda (n = 2), Tanzania (n = 5), Rwanda (n = 4), Cameroon (n = 1) and Sri-Lanka (n = 2) commercially available in the Kenyan market. The estimated Limit of Detection (LOD) of the current method was 0.01% L-theanine. The L-theanine content ranged from below the detection limit (<0.01% L-theanine) to 1.60% L-theanine on a dry weight (d.w) basis. Statistically significant differences (p < 0.05) were observed in the L-theanine contents of black, green and flavoured teas. Rwandan green tea contained the highest L-theanine content with 1.60% d.w. whereas six of the seven flavoured teas had very low theanine levels (<0.01%) that could not be quantified by the current method.
Despite the use of similar cultivars in the smallholder tea sector in Kenya, resultant black tea quality varies. These variations could in part be arising from the formation of varying quantities and ratios of the black tea quality precursor compounds with agro-ecological zones of production. This study evaluated the variations in the caffeine and flavon-3-ol profiles of three cultivars (SFS 150, TRFK 31/8 and TRFK 303/577) of tea from smallholder tea farms in three agro-zones in Kenya. Overall, there were significant variations (p less than or equal to0.05) in the levels of caffeine and flavan-3-ols due to cultivars and agro-ecological zones of production. In the same cultivar, the components varied (p less than or equal to0.05) with an ecological area of production. The patterns in the changes were not systematically leading significant ecological zone x cultivar interactions effects in gallic acid, catechin, and epicatechin gallate. This demonstrated that it may not be predictable how the quality of clonal tea may vary when produced in different agro-ecological zone. Consequently, a high-quality clone in one agro-ecological zone may not replicate the same characteristics in the different agro-ecological zone. It is, therefore, necessary to test new clones in new environments before they are extensively exploited in these environments. The current findings suggest that flavon-3-ols may not be potential factors in the discrimination of tea quality within the ecological zones of Kenya.
A study was carried out to quantitatively estimate the L-theanine content in 19 teas commercially available in the Kenyan market by High Performance Liquid Chromatography (HPLC). The test tea samples analyzed were green (<italic>n</italic> = 4), black (<italic>n</italic> = 8) and flavored (<italic>n</italic> = 7) teas from different origins viz., Kenya (<italic>n</italic> = 4), Uganda (<italic>n</italic> = 2), Tanzania (<italic>n</italic> = 5), Rwanda (<italic>n</italic> = 4), Cameroon (<italic>n</italic> = 1) and Sri-Lanka (<italic>n</italic> = 2) commercially available in the Kenyan market. The estimated Limit of Detection (LOD) of the current method was 0.01 % L-theanine. The L-theanine content ranged from below the detection limit (< 0.01 % L-theanine) to 1.60 % L-theanine on a dry weight (d.w) basis. Statistically significant differences (p < 0.05) were observed in the L-theanine contents of black, green and flavoured teas. Rwandan green tea contained the highest L-theanine content with 1.60 % d.w. whereas six of the seven flavoured teas had very low theanine levels (< 0.01 %) that could not be quantified by the current method.
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