Chemical analysis and antioxidant activity of some rooibos tea products

Abstract

The Rooibos tea, known as well as red tea, has lately gain attention due to its reported rich antioxidant composition. The ai m of this research was to determine the polyphenol content and antioxidant capacity of 6 commercial types of Rooibos tea available on the Romanian market. The analyses of polyphenolic compounds were carried out using chromatographic and spectrophotometric methods. The total polyphenol content (TPC) was assessed by the Folin-Ciocâlteu method and some polyphenols were identified by HPLC: ferulic, sinapic acids, hyperoside, isoquercitrin, rutin, quercitrin, quercetin, luteolin, kaempferol etc. The results showed qualitative and quantitative differences between the samples. The evaluation of antioxidant capacity was performed using DPPH (α,α-diphenyl-β-picrylhydrazyl) and FRAP (ferric reducing antioxidant power) methods, and a moderate activity has been highlighted for all the analysed samples.