title: Evaluation of the antioxidant properties of fruit and flavoured black teas.
abstract: OBJECTIVE
  Antioxidant 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.
  
  
  METHODS
  Folin-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.
  
  
  RESULTS
  Flavoured 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.
authors.affiliation: Department of Chemistry, University of Warsaw, Pasteura 1, 02-093, Warsaw, Poland.
authors.forename: Anna
authors.initials: A
authors.lastname: Pękal
authors.forename: Paulina
authors.initials: P
authors.lastname: Dróżdż
authors.forename: Magdalena
authors.initials: M
authors.lastname: Biesaga
authors.forename: Krystyna
authors.initials: K
authors.lastname: Pyrzynska
mesh_terms: D000975:Antioxidants / Q000032:analysis*; D001628:Beverages / Q000032:analysis*; D002392:Catechin / Q000032:analysis; D002851:Chromatography, High Pressure Liquid; D004341:Drug Evaluation; D005503:Food Additives; D005638:Fruit / Q000737:chemistry; D010936:Plant Extracts / Q000032:analysis*; D011794:Quercetin / Q000032:analysis; D012431:Rutin / Q000032:analysis; D013649:Taste; D013662:Tea / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D005503:Food Additives; D010936:Plant Extracts; D013662:Tea; D012431:Rutin; D002392:Catechin; D011794:Quercetin