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.
Over 60% of tea in Kenya is produced by smallholder tea farmers distributed in the East and West of the Rift Valley. With all smallholder tea farmers using the same production technologies including planting materials, the quality of tea from different agro-ecological zones should be the same. However, black teas attract different prices. This study compared levels of leaf quality, catechins, and polyphenols in green leaf and quality parameters of black tea from twelve factories in three different agro-ecological zones in Kenya and assessed the relationships between the green leaf quality parameters and black tea quality parameters. The catechins contents, the black tea quality parameters, and sensory evaluations changed (p less than or equal to0.05) between the factories and with an agro-ecological zone of production. All black teas had high antioxidant activities, which differed (p less than or equal to0.05) across the factories and zones. Despite the use of same agronomic inputs in the smallholder tea growing zones in Kenya, the quality of resultant black teas was largely influenced by the environmental factors in the different regions. It is therefore not possible to produce black teas of the same quality across the country. Despite the variations, all regions exhibited high levels of black tea quality parameters and sensory evaluation, re-affirming the Kenyan smallholder black teas are of high quality. The high antioxidant activities suggest possible beneficial pharmacological activities from consumption the teas. The green leaf quality (leaf count) were significantly (p less than or equal to0.05) correlated with black tea brightness and all sensory evaluation parameters, demonstrating high benefits from good plucking standards. Green leaf gallic acid, epigallocatechin, epicatechin, epigallocatechin gallate, and total catechins levels were related (p less than or equal to0.05) to black tea total polyphenols and all sensory evaluation parameters. In addition, the green leaf caffeine, epicatechin, epigallocatechin gallate, and total catechins influenced (p less than or equal to0.05) theaflavins in black tea. These green leaf parameters are therefore key drivers of Kenyan plain black tea quality.
The tea plant absorbs dissolved nutrients from soils for its normal growth and development, though to different extents. Nutrients play vital roles in various metabolic processes, their deficiency or excess being deleterious to living organisms. A study was carried out to quantitatively assess the inorganic nutrient content (K, P, Ca, Mn, Fe, Zn and Cu) of twelve black tea samples sourced from Murang'a, Meru and Kisii tea growing agro-ecological areas in Kenya. K and P were quantified using a flame photometer and a UV-Vis spectrophotometer respectively whereas Ca, Mn, Fe, Zn and Cu were quantified using an Atomic Absorption Spectrophotometer (AAS). The general accumulation pattern of the inorganic nutrients in the tea samples was established to be; K (1.6% ± 0.05% -2.1% ± 0.01%) > P (0.30% ± 0.01% -0.37% ± 0.04%) > Ca (0.16% ± 0.01% -0.62% ± 0.03%) > Mn (0.07% ± 0.009% -0.13% ± 0.004%) > Fe (136 ± 8 -320 ± 5 µg/g) > Zn (27 ± 1 -39 ± 7 µg/g) > Cu (10 ± 3 -16 ± 1 µg/g). Statistically significant differences (p < 0.05) were observed in the inorganic nutrient contents of the black tea from the different tea factories as well as agro-ecological areas. These data demonstrate the tea plant's ability to accumulate the studied nutrients, further underlining tea consumption as a potential dietary source of the nutritionally essential inorganic nutrients.
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