Variation in Levels of Flavonols Myricetin, Quercetin and Kaempferol—In Kenyan Tea (<i>Camellia sinensis L.</i>) with Processed Tea Types and Geographic Location

The aim of this study was to determine the levels of myricetin, quercetin, and kaempferol in green and black Kenyan types in relation to geographic location of production. Tea samples were extracted before chromatographic separations with a Shimadzu 20A HPLC coupled with PDA. Flavonol levels were quercetin > kaempferol > myricetin. Teas from east of rift, had quercetin 1.25-1.83 mg/g and 1.29-1.71 mg/g for green and black types, respectively. Kaempferol levels were between 1.28-1.72 mg/g in green and 1.36-1.76 mg/g in black tea. Myricetin ranged at 0.40-0.79 mg/g green and 0.12-0.38 mg/g black tea types. Total flavonols in green tea were highest at 4.28 mg/g while black tea was 3.83 mg/g. These trends agree well with those observed in teas west of the rift. For tea types, myricetin and kaempferol showed a significant difference (P ≤ 0.05) between green and black teas. Total flavonols showed no significant difference. Kenyan teas are a potential dietary source of flavonols myricetin, quercetin, and kaempferol as evidenced by the significant quantities recorded in this study.

Extraction and Quantification of Total Polyphenol Content in Different Parts of Selected Tea Cultivars

Tea (Cammelia sinensis) is the most widely consumed beverage in the world and has been reported to have unlimited health benefits due to its antioxidant properties. There is a high correlation between polyphenol compounds with antioxidant properties. Tea leaves are a major source of polyphenols. The aim of the present investigation was to determine the approximate level of polyphenols in different other parts of the tea plant to give comparative data on obtaining extracts that can be used to design products through value addition to assist in the prevention of diseases associated with oxidative stress. Twenty-one selected region specific tea varieties were used to obtain roots, flowers, leaves and barks. Leaves were prepared by microwaving and the remaining portions processed as green non-aerated teas and black aerated tea. Roots, barks, flowers were sun-dried and milled. Total polyphenol content was determined by calorimetric method using Folin-Ciocalteu reagent. The obtained results suggest that different parts of tea plant have varying numbers of total polyphenols with microwaved leaves having mean levels at 23.1%, steamed leaves (non-aerated green tea) at 22.37%, aerated leaves at 15.51%, barks at 14.92%, flowers at 10.62% and roots at 1.48%.