Determination of Residual Catechins, Polyphenolic Contents and Antioxidant Activities of Developed Theaflavin-3,3'-Digallate Rich Black Teas

This study was carried out to characterize total residual catechins and their fractions, polyphenoliccontents and antioxidant activities of black teas enriched with high levels of theaflavin-3,3’-digallate. The made teas were processed from eleven selected cultivars. A comparative study wascarried out between the processed teas and those from commercially grown Kenyan cultivars inrelation to the above chemical parameters. A correlation matrix analysis was also conducted tofind out whether a relationship existed between the antioxidant activities and the said chemicalparameters. The total residual catechins were found to range between 3.10% and 8.08%. The totalpolyphenol levels varied between 19.00% and 28.90%, while the antioxidant activities of the teasranged from 82.70% to 91.70%. There was a significant p u003c 0.001 correlation between the antioxidantactivity and total polyphenols (r = 0.8948). There was also a high correlation p u003c 0.001between the antioxidant activity and total catechins (r = 0.8878). Out of the four catechin fractions,the antioxidant activity correlated most with EGCG (r = 0.8774). The total polyphenolic contentsand antioxidant activities for most of the cultivars were comparable to those of the green tea referencestandard. From the figures obtained, it can be concluded that the most of the newly developedblack teas of the selected cultivars have higher quality and enhanced antioxidant activitiesand that they can be recommended for commercial production.