Evaluation of the antioxidant properties of fruit and flavoured black teas

Abstract

ObjectiveAntioxidant properties of the water extracts of the commercial bagged fruit and flavoured black teas were evaluated and compared with typical black teas of C. sinensis.MethodsFolin–Ciocalteu (FC) assay, cupric ion reducing antioxidant capacity (CUPRAC) and DPPH radical method were used for these purposes. The content of selected flavonoids and phenolic acids was also determined by high-performance liquid chromatography with tandem mass spectrometry in the negative electrospray ionization mode.ResultsFlavoured black teas contain significantly higher level of catechins, quercetin, and rutin, while the content of chlorogenic and caffeic acids as well as naringin and hesperidin was higher in fruit teas. Supplementation with these flavonoids could reduce blood glucose. In FC and DPPH assays, the antioxidant properties of studied tea infusion increases in the order: fruit tea < flavoured black tea > premium black tea, while in CUPRAC method, some aromatized teas exhibit the highest antioxidant properties. Tea infusions with nice smell of fruits would also support the human diet with some source of antioxidants.

Evaluation of Aluminium Complexation Reaction for Flavonoid Content Assay

“…Under conditions in procedure 1, herbal tea infusion of St. John's wort exhibited the absorbance peak characteristic for flavonoids and luteolin (from flavanones family), while for green and fruit tea infusions as well as for orange juice sample, the maximum is more shifted in UV region (390-400 nm). These samples contain significant amount of flavonones (Pękal et al 2011a;Pękal et al 2013); however, their contribution in absorbance value measured above 400 nm in procedure 1 is very low. Under conditions used in procedure 2, sample of orange juice did not exhibit absorbance above 500 nm.…”

Flavonoid Content and Antioxidant Properties of Different Black Tea Infusions

“…Quantification of compounds was done from the calibration curves obtained in Multiple Reaction Mode (MRM) [10]. All the compounds showed a good linearity in the range of 0.01 -40 mg/L with regression coefficients > 0.99.…”

“…Significantly higher values were determined for "pure" black tea infusions (830-1119 mg GA/L) in comparison to aromatized teas (345-701 mg GA/L). Black teas contain higher content of rutin (Table 2) as well as catechin and their derivatives [10]. They may contain also, except determined flavonoids, other compounds with reducing properties.…”

Solubility of naringin in ethanol and water mixtures from 283.15 to 318.15 K

“…Naringin shows the ability of an antioxidant [5,6], as well as its anti-inflammatory [5,7], anti-cancer (breast cancer) [8], anti-allergic [9], and anti-diabetic activities [10,11].…”