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  • Isolation of active ingredients from green tea (Fanning Bellas, China) [Elektronski vir]
    Perva, Amra ; Škerget, Mojca ; Knez, Željko
    Valuable active ingredients in green tea leaves (Camellia sinensis) are polyphenolic compounds, which are found in the range from 5 to 30 wt. % in raw material and are usually isolated by solvent ... extractions. Tea leaves also contain caffeine, an alkaloid, which contributes to stimulant properties of tea in addition to positive pharmacological properties caused by polyphenolic compounds, which act as natural antioxidants. In the frame of presented study, lower grade green tea leaves (variety Fanning Belas, China) used in teabags were extracted with various solvents (acetone, ethanol, methanol, acetonitrile, water) employing different extraction conditions of temperature,time and ratio material:solvent. Raw extracts were analysed on major catechins (EC, ECG, EGC, EGCG), caffeine, three flavonols (myricetin, kaempherol, quercetin), and proanthocyanidins. Raw material was found to contain 190.8 g of major catechins and 36.0 g of caffeine and 5.2 g of flavonols per kg of dry material. The content of major catechins in green tea extracts obtained with different aqueous solvents varied from 280 to 580 g catechins/kg extract, while content of caffeine in extract was in average 75g/kg. Content of the three flavonols and proanthocyanidins was in the range from 6-20 g/kg and 12-19 g/kg, respectively. Different extraction procedures with water were also investigated and optimal conditions determined: maximum reached extraction efficiency of catechins with water was obtained at 80°C after 20 min (97 %) and at 95°C after 10 min of extraction (90 %). Decaffeinated green tea leaves, which were obtained by high-pressure extraction with CO2, were extracted at optimal conditions and a decaffeinated green tea extract rich in major catechins was obtained.
    Vir: CHISA 2004 [Elektronski vir] : CD-ROM of full texts (8 str. (0611))
    Vrsta gradiva - prispevek na konferenci
    Leto - 2004
    Jezik - angleški
    COBISS.SI-ID - 8959766

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