Abstract:
ver 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 ≤0.05) between the factories and with an agro-ecological zone of production. All black teas had high antioxidant
activities, which differed (p ≤0.05) 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 ≤0.05) 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 ≤0.05) to black tea total polyphenols
and all sensory evaluation parameters. In addition, the green leaf caffeine, epicatechin, epigallocatechin gallate, and total catechins influenced
(p ≤0.05) theaflavins in black tea. These green leaf parameters are therefore key drivers of Kenyan plain black tea quality
