title: Phenolic content and antioxidative capacity of green and white tea extracts depending on extraction conditions and the solvent used.
abstract: The efficiencies of different solvents in the extraction of phenolics from bagged and loose leaves of white and green tea, after different extraction times, as well as the antioxidative capacity of the obtained extracts, were investigated. The developed HPLC method has the potential to separate and determinate 17 phenolics widely distributed in plants, but in investigated tea extracts only four catechins and traces of three flavonols and one flavone were separated and detected based on comparison with authentic standards. The extraction efficiency of phenolics depended strongly on the time of extraction and the solvents used. The extraction of catechins from green tea was significantly affected by the form (bagged or loose) of the tea, whereas this effect was shown not to be statistically significant for white tea. Green tea was a richer source of phenolics than was white tea. The extraction of phenolics from white tea by water could be accelerated by the addition of lemon juice. Aqueous ethanol (40%) was most effective in the prolonged extraction of catechins. The antioxidative capacity of the investigated tea extracts correlated with their phenolic content.
authors.affiliation: Department of Biology, Faculty of Science, University of Zagreb, Rooseveltov trg 6, 10000 Zagreb, Croatia. Electronic address: gordana@botanic.hr.
authors.forename: Gordana
authors.initials: G
authors.lastname: Rusak
authors.affiliation: Department of Food Processing and Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 10000 Zagreb, Croatia.
authors.forename: Draženka
authors.initials: D
authors.lastname: Komes
authors.affiliation: Department of Biology, Faculty of Science, University of Zagreb, Rooseveltov trg 6, 10000 Zagreb, Croatia.
authors.forename: Saša
authors.initials: S
authors.lastname: Likić
authors.affiliation: Department of Food Processing and Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 10000 Zagreb, Croatia.
authors.forename: Dunja
authors.initials: D
authors.lastname: Horžić
authors.affiliation: Department of Food Processing and Engineering, Faculty of Food Technology and Biotechnology, University of Zagreb, Pierottijeva 6, 10000 Zagreb, Croatia.
authors.forename: Maja
authors.initials: M
authors.lastname: Kovač
keywords: Antioxidant activity; Camellia sinensis; Catechins; Green tea; HPLC; Phenolics; White tea