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KWACH B.O.,Maseno University | OWUOR P.O.,Maseno University | KAMAU D.M.,Tea Research Foundation of Kenya | MSOMBA S.W.,Tea Research Institute of Tanzania | UWIMANA M.A.,National Agricultural Export Development Board NAEB
Experimental Agriculture | Year: 2015

Theaflavins contribute to astringency and brightness while thearubigins contribute to colour and mouth feel of black tea. Green leaf flavan-3-ols influence levels and distribution of theaflavins and thearubigins in black tea and are black tea quality precursor compounds. Caffeine also contributes to tea quality. Although location of production and nitrogenous fertilizer rates influence black tea quality, it is not known if the variations arise from the levels and distribution of the precursor compounds in green leaf or other factors. The variations and distribution of the flavan-3-ols and caffeine in young green leaves of clone TRFK 6/8 due to nitrogen fertiliser rates in seven locations within Eastern Africa were evaluated. Green leaf comprising two leaves and a bud were harvested from each plot, and subjected to HPLC analysis for caffeine, total polyphenol, dihydroxyflavan-3-ols, trihydroxyflavan-3-ols, ratios of trihydroxyflavan-3-ols to dihydroxyflavan-3-ols and total catechins levels. Results were subjected to statistical analysis using split plot design, with locations as main treatments and nitrogen rates as the sub-treatment. Caffeine and flavan-3-ols levels changed (p ≤ 0.05) with location of production, demonstrating that even with use of same cultivar and similar agronomic management quality of tea from one location cannot be replicated in another location. Caffeine levels increased (p ≤ 0.05) with rise in nitrogen fertilizer rate in all locations, but the extent depended on location. Total polyphenols and individual flavan-3-ols showed an inverse quadratic response, except EGCG that linearly decreased (p ≤ 0.05) in some locations, due to increasing rates of nitrogen fertilizer. Similar responses in the black tea quality parameters had been observed in previous studies. The black tea quality results were therefore directly influenced by the green leaf precursor compound patterns. Region specific nitrogenous fertilizer rates need development to ensure high tea quality. Copyright © Cambridge University Press 2015

Owuor P.O.,Maseno University | Okal A.W.,Maseno University | Kamau D.M.,Tea Research Foundation of Kenya | Msomba S.W.,Tea Research Institute of Tanzania | And 3 more authors.
Journal of Food, Agriculture and Environment | Year: 2013

Tea agronomic recommendations in Lake Victoria basin are uniform, despite different regions producing teas of different qualities and yields. It is not known if these differences arise from variations in cultivars, agronomic inputs, management or the environment. A trial was conducted in Kenya to determine if noted differences persist in the same cultivar under same agronomic inputs, and management. Green leaf chemical quality precursors influence black tea quality. Unsaturated fatty acids in green tea leaves break down producing volatile flavour compounds, key tea aroma compounds. The C6 aldehydes, alcohols and acids, heptanal, heptanol, nonanol, nonanal, E-2-nonenal, Z-2,Z-4-nonadienal and E-2,E-4-nonedienal in black tea are products of unsaturated fatty acids breakdown during processing. They impart green grassy aroma to tea thereby reducing its quality. Nitrogenous fertilizer and harvesting are the most expensive agronomic inputs in tea production. Effects of these inputs on fatty acid levels in clone BBK 35 grown in five sites in Kenya are reported herein. The shoots contained lauric, myristic, palmitic, palmitoleic, stearic, oleic, linoleic and linolenic acids. Linolenic acid dominated the acids followed by linoleic acid and there were significant (P<0.05) variations in the amounts of acids. The order of the other acids changed with location of production. The acids increased with rise in the rates of nitrogenous fertiliser and long plucking intervals. The rates and extent of increase in the fatty acid levels due to increasing nitrogenous fertiliser rates varied with locations leading to significant (P<0.05) interaction effects. Significant (P<0.05) interaction effects were also observed between location of production and plucking intervals, and nitrogenous fertiliser rates and plucking intervals. To produce low levels of fatty acids thereby increasing black tea quality, low levels of nitrogen and short plucking intervals are necessary. Despite using same rate of nitrogen or plucking intervals, the fatty acid levels, hence aroma quality will change with location of production. Different regions therefore require specific nitrogen fertiliser rates and plucking intervals to produce optimal amounts of fatty acids for production of high quality black tea. Development of region specific agronomic inputs is recommended to produce high quality black teas.

Okinda Owuor P.,Maseno University | Kamau D.M.,Tea Research Foundation of Kenya | Kamunya S.M.,Tea Research Foundation of Kenya | Jondiko E.O.,Maseno University | And 2 more authors.
Journal of Food, Agriculture and Environment | Year: 2013

Tea is an economic crop in the Lake Victoria basin of East Africa, earning high foreign exchange and creating employment opportunities especially in the rural poor regions. It is grown under varying environments causing differences in yields and quality. However, agronomic recommendations are uniform throughout the region despite these differences. It is necessary to develop region specific agronomic recommendations to realise economic returns from tea enterprises. Nitrogenous fertiliser use and harvesting are the most costly agronomic inputs and their incorrect use reduces yields and black tea quality. Trials using clone BBK 35 were conducted at Timbilil, Changoi, Kipkebe and Sotik Highlands within the Lake Victoria basin in Kenya to determine yields and black tea quality responses of the cultivar to locations of growth, nitrogenous fertiliser rates and plucking intervals. Yields and black tea quality significantly (P < 0.05) varied with the environment. Similarly, rates and extents of yields and quality responses varied with locality, demonstrating that despite uniform agronomic inputs, different locations need different levels of inputs for optimal economic returns. Black tea quality declined with high rates of nitrogenous fertiliser and long plucking intervals. There was yield increase at Changoi and decrease at Sotik Highlands with long plucking intervals. It is concluded that region specific agronomic recommendations are necessary to realise high yields and quality black teas. However, low rates of nitrogenous fertilisers of about 100 kg N ha-1 year-1 and short plucking intervals produced high quality black teas.

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