Tea Research Foundation of Kenya

Kericho, Kenya

Tea Research Foundation of Kenya

Kericho, Kenya
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Azapagic A.,University of Manchester | Bore J.,Tea Research Foundation of Kenya | Cheserek B.,Tea Research Foundation of Kenya | Kamunya S.,Tea Research Foundation of Kenya | Elbehri A.,Food and Agricultural Organization of the United Nations
Journal of Cleaner Production | Year: 2015

Kenya is the third largest producer of tea in the world, the majority of which is exported, contributing 20% to the total national income from exports. Yet, its environmental impacts are currently unknown. This study considers for the first time one of the impacts - the global warming potential - of production and consumption of Kenyan black tea. The system boundary is from 'cradle to grave'. Both small- and large-scale production of tea is considered. The functional unit is defined as 1kg of dry tea and the tea is assumed to be consumed in the UK. The results suggest that the total impact of tea is equal to 12.45kg CO2 eq./kg of dry tea for the large-scale and 12.08kg CO2 eq./kg for the small-scale production, indicating that the scale of production does not influence the impact. The main contributor is tea consumption which is responsible for 85% of the impact because of the electricity used to boil water. Tea cultivation and processing contribute around 10% to the total. The contribution of transport is relatively small (4%). The global warming potential from waste management is negative because of the credits for recycling of post-consumer tea packaging. The results are most sensitive to consumer behaviour, with the impact almost doubling with doubling the amount of water boiled for each cup of tea. Drinking tea with milk has even greater impact, increasing the total impact by up to three times. Appropriate consumer engagement programmes are needed to encourage behavioural change. © 2015 Elsevier Ltd.

Muoki R.C.,Institute of Himalayan Bioresource Technology | Muoki R.C.,Tea Research Foundation of Kenya | Paul A.,Institute of Himalayan Bioresource Technology | Kumar S.,Institute of Himalayan Bioresource Technology
Functional and Integrative Genomics | Year: 2012

Abstract Drought poses a significant threat to tree plants including tea [Camellia sinensis (L.) O. Kuntze] that yields a popular beverage "tea." Consequence of drought is heat and salt stress, for which data on molecular response in tree species are not available. The present work analyzed drought-responsive subtracted cDNA libraries of tea to identify drought-responsive genes. Temporal and spatial gene expression suggested the involvement of chaperones as one of the major mechanisms to protect the plant against drought-related damages. A common response of thaumatin like protein, chitinase, and late embryogenesis abundant protein3 across four stresses suggests these to be useful targets to generate "drought stress proof" tea. ©Springer-Verlag 2012.

Muoki R.C.,Institute of Himalayan Bioresource Technology | Muoki R.C.,Panjab University | Muoki R.C.,Tea Research Foundation of Kenya | Paul A.,Institute of Himalayan Bioresource Technology | And 3 more authors.
Molecular Biotechnology | Year: 2012

Tea, a beverage crop, is a rich source of polyphenols and polysaccharides which greatly attribute to its importance. However, oxidation and precipitation of these compounds during nucleic acids extraction is a limitation to molecular biology and genomic studies. On isolation of total RNA from root tissue using established protocols, difficulties were encountered in terms of purity and quantity of isolated RNA or some of the methods were time-consuming and also yields were low. The present communication combines a phenol-based RNA isolation protocol with a cetyltrimethylammonium bromide-based procedure with appropriate modifications. This protocol successfully isolated RNA from tap root tissue in 2-3 h as compared with 16 h reported by the previous method. Also, RNA yield was higher by more than fourfold. The RNA isolated by this protocol was successfully used for downstream applications such as RT-PCR and the construction of suppression subtractive hybridization library. The developed protocol worked well with other plant tissue with high polyphenols and polysaccharides contents. © 2011 Springer Science+Business Media, LLC.

Rashid K.,Egerton University | Rashid K.,Tea Research Foundation of Kenya | Wachira F.N.,Tea Research Foundation of Kenya | Wachira F.N.,Association for Strengthening Agricultural Research in Eastern and Central Africa | And 5 more authors.
Nutritional Neuroscience | Year: 2014

Studies on antioxidants as neuroprotective agents have been hampered by the impermeability of the blood brain barrier (BBB) to many compounds. However, previous studies have shown that a group of tea flavonoids, the catechins, are brain permeable and neuroprotective. Despite this remarkable observation, there exist no data on the bioavailability and pharmacological benefits of tea anthocyanins (ACNs) in the brain tissue. This study investigated the ability of Kenyan purple tea ACNs to cross the BBB and boost the brain antioxidant capacity. Mice were orally administered with purified and characterized Kenyan purple tea ACNs or a combination of Kenyan purple tea ACNs and coenzyme- Q10 at a dose of 200 mg/kg body weight in an experiment that lasted for 15 days. Twenty-four hours post the last dosage of antioxidants, CO2 was used to euthanize the mice after which the brain was excised and used for various biochemical analyses. Brain extracts were analysed by high-performance liquid chromatography for ACN metabolites and spectrophotometry for cellular glutathione (GSH). Kenyan purple tea ACNs significantly (P < 0.05) raised brain GSH levels implying boost in brain antioxidant capacity. However, co-administration of both antioxidants caused a reduction of these beneficial effects implying a negative interaction. Notably, ACN metabolites were detected in brain tissue of ACN-fed mice. Our results constitute the first demonstration that Kenyan purple tea ACNs can cross the BBB reinforcing the brain's antioxidant capacity. Hence, the need to study them as suitable candidates for dietary supplements that could support antioxidant capacity in the brain and have potential to provide neuroprotection in neurodegenerative conditions. © W. S. Maney & Son Ltd 2014.

Rashid K.,Egerton University | Rashid K.,Tea Research Foundation of Kenya | Wachira F.N.,Tea Research Foundation of Kenya | Wachira F.N.,Association for Strengthening Agricultural Research in Eastern and Central Africa | And 5 more authors.
Parasitology International | Year: 2014

Human African trypanosomiasis (HAT) is a tropical disease caused by two subspecies of Trypanosoma brucei, the East African variant T. b. rhodesiense and the West African variant T. b. gambiense. Melarsoprol, an organic arsenical, is the only drug used to treat late stage T. b. rhodesiense infection. Unfortunately, this drug induces an extremely severe post treatment reactive encephalopathy (PTRE) in up to 10% of treated patients, half of whom die from this complication. A highly reproducible mouse model was adapted to assess the use of Kenyan purple tea anthocyanins and/or coenzyme-Q10 in blocking the occurrence of PTRE. Female Swiss white mice were inoculated intraperitoneally with approximately 104 trypanosome isolate T. b. rhodesiense KETRI 2537 and treated sub-curatively 21days post infection with 5mg/kg diminazene aceturate (DA) daily for 3days to induce severe late CNS infection that closely mirrors PTRE in human subjects. Thereafter mice were monitored for relapse of parasitemia after which they were treated with melarsoprol at a dosage of 3.6mg/kg body weight for 4days and sacrificed 24h post the last dosage to obtain brain samples. Brain sections from mice with PTRE that did not receive any antioxidant treatment showed a more marked presence of inflammatory cells, microglial activation and disruption of the brain parenchyma when compared to PTRE mice supplemented with either coenzyme-Q10, purple tea anthocyanins or a combination of the two. The mice group that was treated with coenzyme-Q10 or purple tea anthocyanins had higher levels of GSH and aconitase-1 in the brain compared to untreated groups, implying a boost in brain antioxidant capacity. Overall, coenzyme-Q10 treatment produced more beneficial effects compared to anthocyanin treatment. These findings demonstrate that therapeutic intervention with coenzyme-Q10 and/or purple tea anthocyanins can be used in an experimental mouse model to ameliorate PTRE associated with cerebral HAT. © 2014 Elsevier Ireland Ltd.

Owuor O.P.,Maseno University | Kamau D.M.,Tea Research Foundation of Kenya | Jondiko E.O.,Maseno University
Journal of Food, Agriculture and Environment | Year: 2010

Variations in requirements for tea production in Kenya and factors controlling growth and production of secondary metabolites responsible for the quality parameters are indicative of the need for non-uniform recommendations. Nitrogen is the main nutrient for which tea shows easily demonstrable yield and quality responses. Fertilizer applications at rates between 100 and 250 kg N/ha/year of NPKS 25:5:5:5 are currently recommended in tea production. Although yield and black tea quality variations with nitrogen rates had been observed in the past, the studies were at single geographical locations. Where comparisons were done at different locations, the genotypes were different making it impossible to isolate environmental and genotypic effects. The response of single genotype to varying rates of nitrogen in the major tea growing areas has not been reported. Consequently, it is not known if the recommended nitrogen rates are optimal in all tea growing areas for production of high yields and good quality black teas. Trials were conducted in five major tea growing regions of Kenya to quantify the yields and illustrate plain tea quality parameters responses of cultivar BBK 35 to varying rates of NPKS 25:5:5:5 fertiliser applied at 0, 75, 150, 225 and 300 kg N/ha/year. Yields were recorded for a period of ten years (1998 to 2007). Pluckable shoots from the plots were processed into black tea and analyses for quality carried out in 2007. Yields significantly (P ≤ 0.05) increased while quality declined with increasing rates of nitrogen. The mean yield varied in the following order: Sotik Highlands ≥ Changoi > Karirana > Kipkebe ≥ Timbilil. Also plain black tea quality as measured by theaflavins, thearubigins, total colour, brightness and sensory evaluations varied with geographical area of production. The theaflavins declined in the order: Changoi ≥ Karirana > Timbilil ≥ Kipkebe > Sotik Highlands. There was significant (P ≤ 0.05) interaction between geographical area of production and nitrogen fertilizer rates in yields demonstrating that yield response of BBK 35 to nitrogen varies with localities. The actual optimal nitrogen for the individual locations, however, will also be affected by quality, cost of production including cost of fertilisers and realised tea prices. Location specific recommendations need to be developed to promote high yields and production of high quality black teas in the different tea growing regions.

Kilel E.C.,Egerton University | Faraj A.K.,Egerton University | Wanyoko J.K.,Tea Research Foundation of Kenya | Wachira F.N.,Tea Research Foundation of Kenya | Mwingirwa V.,Kenya Tea Development Agency
Food Chemistry | Year: 2013

The Kenyan tea industry wishes to diversify its tea products, and in line with this, anthocyanin - rich teas were developed at the Tea Research Foundation of Kenya. These teas have purple-coloured leaves and the green colour is masked. In total, 12 accessions of the purple leaf coloured teas and 2 standard tea varieties were studied. Clones Hanlu and Yabukita are Chinese and Japanese tea varieties, respectively, known for good green tea, and they were used as reference standards. Little if any research had been done to characterize the quality of these purple leaf coloured teas and this study investigated their total polyphenols (TPP), catechins, caffeine, gallic acid and theanine. These are the major green tea quality parameters. Results showed that the new Kenyan tea clones had higher total polyphenols than had the reference standard tea varieties, which had 17.2% and 19.7% while the lowest among the Kenyan clones was 20.8%. On catechin quality index, K-purple and TRFK 91/1 showed high index values of 15.9 and 13.3, respectively, while clones TRFK 83/1 and 73/5 showed low index values of 0.74 and 1.0, respectively. Hanlu had the highest caffeine level with 2.42% while clones TRFK KS 3, TRFK KS 2 and TRFK 83/1 had relatively high caffeine levels among the purple leaf coloured teas, with 2.33%, 2.22% and 2.21%, respectively. Clone TRFK 73/5 had the lowest caffeine content, with 1.16%. Theanine analysis showed that most purple leaf coloured teas had more theanine than had the reference standard clones, except TRFK 83/1 and K-purple, which were lower than the reference standard clones. The implication of the green tea chemical quality parameters is also discussed. It is concluded that all the studied clones/varieties have above the minimum 14% of total polyphenols. Clones K-purple and TRFK 91/1 showed high green tea quality indices with the latter doubling with high levels of theanine; hence its highly recommended for green tea manufacture. © 2013 Elsevier Ltd. All rights reserved.

Kerio L.C.,Tea Research Foundation of Kenya | Wachira F.N.,Association for Strengthening Agricultural Research in East and Central Africa ASARECA | Wanyoko J.K.,Tea Research Foundation of Kenya | Rotich M.K.,Egerton University
Food Chemistry | Year: 2013

Black (aerated) and green (unaerated) tea products, processed from 10 green and 18 purple leaf coloured cultivars of Kenyan origin, and two tea products, from the Japanese cultivars, Yabukita and Yutakamidori, were assayed for total polyphenols (TP) content, individual catechin profiles and in vitro antioxidant capacity (AA). In addition, the phenolic content of the tea products was determined using the Folin-Ciocalteu phenol reagent. Catechin fractions were identified using reverse phase high performance liquid chromatography (HPLC) with a binary gradient elution system. The AA% of the tea products was determined using a 2,2′-diphenyl picrylhydrazyl (DPPH) radical assay method. The results showed that TPs, catechin profiles and antioxidant activities were significantly (p ≤ 0.05) higher in unaerated than in aerated teas. Tea products from the purple leaf coloured tea cultivars had levels of TPs, total catechin (TC) and antioxidant activities similar to those from the green leaf coloured cultivars, except for teas from the Japanese cultivars that were very low in the assayed parameters. Caffeine content was significantly (p ≤ 0.05) lower in products from the purple leaf coloured cultivars than in those from the green leaf coloured tea cultivars. Antioxidant activity (%) was higher in tea products from the Kenyan germplasm than in those from the Japanese cultivars. Antioxidant potency of tea products was significantly (r = 0.789, p ≤ 0.01) influenced by the total anthocyanin content of the purple leaf coloured cultivars. Cyanidin-3-O-glucoside was the anthocyanin most highly correlated with AA% (r = 0.843, p ≤ 0.01 in unaerated tea). Total catechins in the unaerated products from the green leaf coloured tea cultivars were also significantly correlated with antioxidant capacity (r = 0.818 p ≤ 0.01). Results from this study suggest that the antioxidant potency of teas is dependent on the predominant flavonoid compound, the type of tea cultivar and the processing method. © 2012 Elsevier Ltd. All rights reserved.

Kerio L.C.,Tea Research Foundation of Kenya | Wachira F.N.,Tea Research Foundation of Kenya | Wachira F.N.,Egerton University | Wanyoko J.K.,Tea Research Foundation of Kenya | Rotich M.K.,Egerton University
Food Chemistry | Year: 2012

Characterization and quantification of anthocyanins in selected tea cultivars processed into black (aerated) and green (unaerated) tea products was carried out in this study. The anthocyanins were extracted from tea products processed from a number of newly bred purple leaf coloured Kenyan tea cultivars (Camellia sinensis) using acidified methanol/HCl (99:1 v/v). Extracted anthocyanins were purified by C18 solid phase extraction (SPE) catridges and characterised by HPLC-UV-Visible. They were identified according to their HPLC retention times, elution order and comparison with authentic standards that were available. Total monomeric anthocyanins were determined by the pH-differential method. Although the tea cultivars gave different yields of anthocyanins, the unaerated (green) teas had significantly (p ≤ 0.05) higher anthocyanin content than the aerated (black) teas. This was attributed to the degradation of anthocyanins by polyphenol oxidase products (catechin O-quinones) formed during the auto-oxidation (fermentation) process of black tea manufacture. Of the six most common natural anthocyanidins, five were identified in the purified extracts from purple leaf coloured tea, in both aerated (black) and unaerated (green) teas namely; delphinidin, cyanidin, pelargonidin, peonidin and malvidin. The most predominant anthocyanidin was malvidin in both tea products. In addition, two anthocyanins namely, cyanidin-3-O-galactoside and cyanidin-3-O-glucoside were also identified. Tea catechins were also identified in the tea products derived from the purple coloured tea cultivars namely, epigallocatechin (EGC), catechin (+C), epicatechin (EC), epigallocatechin gallate (EGCG), and epicatechin gallate (ECG). Correlation between the total catechins versus the total anthocyanins and anthocyanin concentration in unaerated teas revealed significant negative correlations (r = -0.723 * and r = -0.743*, p ≤ 0.05 and p ≤ 0.01, respectively). However, in aerated (black) tea the correlations were insignificant (r = -0.182 and r = -0.241, p > 0.05). © 2011 Elsevier Ltd. All rights reserved.

Korir M.W.,Egerton University | Wachira F.N.,Association for Strengthening Agricultural Research in East and Central Africa ASARECA | Wanyoko J.K.,Tea Research Foundation of Kenya | Ngure R.M.,Egerton University | Khalid R.,Tea Research Foundation of Kenya
Food Chemistry | Year: 2014

Several studies have demonstrated that tea flavonoids protect cells and tissues against free radicals which have been implicated in the etiology of oxidative stress-related disease disorders. However, black tea is commonly consumed with additives that could otherwise affect the bioavailability of the active tea molecules. In this study, the biochemical parameters of Kenyan teas were determined and the effect of added milk and sweeteners on the antioxidant activity of Kenyan teas was investigated. The effect of tea antioxidants on glutathione (GSH) was also evaluated in vivo in a time series study using Swiss mice. Green teas had the highest levels of total polyphenols, total and individual catechins, while black teas had high levels of total thearubigins, total theaflavins and theaflavin fractions. The antioxidant activity was high in green teas though some of the black teas were as efficacious as the green teas. The addition of milk, sugar and honey significantly (p < 0.05) decreased the antioxidant activity of tea in a concentration-dependent manner. Addition of the sweetener, stevia (Stevia rebaudiana Bertoni), showed no significant (p > 0.05) influence on the antioxidant activity of tea and therefore can be recommended as a preferred sweetener for tea. Significantly (p < 0.001) higher levels of GSH were observed in plasma than in other tissues. GSH levels were generally highest 2 h after tea consumption, which indicates the need to repeatedly take tea every 2 h to maximise its potential health benefits. © 2013 Elsevier Ltd. All rights reserved.

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