Faculty of Applied Science and Technology

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Browsing Faculty of Applied Science and Technology by Subject "Antioxidant Activity"

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    Polyphenolic composition and antioxidant activity of Kenyan Tea cultivars
    (2014) Karori, SM; Wachira, FN; Ngure, RM; Mireji, PO
    Polyphenolic fractions in tea are potent bioactive mo lecules. In this study, the polyphenolic composition of 25 different types of Kenyan tea cultivars was de termined using the HPLC and the Folins Ciocalteus spectrophotometric methods. Total Polyphenols, Total Ca techins, individual catechins and Antioxidant Activity were significantly (P<0.05) different among tea varieties, with green tea had the highest levels of Total Polyphenols ranging from (19.70-26.12%), TC (8.51%-17.60%), indivi dual catechins, and AA (86.65-94.50%). In vitro bioassay carried out using 2, 2’-di phenyl picrylhydrazyl radical showed epigallocatechin gallate was the most potent catechin and the most potent in antioxidant activity (r=0.968***). Epigallocatechin (r=0.659***, p<0.001), Epicatechigallate (r=0.454*, p<0.001) and Epicatechin (EC) (r=0.780***, p<0.001) showed signifi cant (p<0.05) antioxidant activity. Black tea contained high levels of Theaflavins and Thear ubigins (2.072% to 17.12%), respectively) which accounted for its antioxidant activit y (r=0.803*** and r=0.859***, respectiv ely). Gallic acid also showed significant (r=0.530*) contribution to the antioxidant activity in black tea. Data obtained from this study reveals that different Kenyan tea cultivars have different polyphenolic co mposition which imparts on their unique biochemical qualities. Gr een and white tea products are rich in catechins, black tea products are rich in TFs and TRs while purple teas are rich in anthocyanins