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Antioxidative substances in selected fruit and herbal teas
Tomková, Martina ; Buňková, Radka (referee) ; Márová, Ivana (advisor)
This diploma project deals with antioxidant and antimutagenic properties of selected herbal and fruit teas commonly used in Czech population. Influence of different tea packaging (bag teas and loose leaf teas) on bioactive compound content was compared. Further, effect of long-term storage in common household conditions was studied. Antioxidant properties of teas were characterized using some group parameters - total antioxidant activity ("Randox Total Antioxidant Status Kit"), total phenolics and total flavonoids - as well as some individual representatives of low molecular weight antioxidants. Higher antixidant content was found in herbal teas than in fruit teas. Comparing bag teas with loose leaf teas higher antioxidant activity was shown in loose leaf teas. Individual antioxidants were analyzed using HPLC method with spectrophotometric detection and verified by on-line LC/MS. IN all tea samples catechins - catechin, epicatechin, epicatechin gallate and other flavonoids - rutin, morin, quercetin, kaempferol, myricetin and luteolin were determined. In most of teas high level of catechin and rutin was detected. The highest level of flavonoids was determined in herbal poured teas. Ascorbic acid content was also determined by HPLC method. Higher vitamine C level was found in most of fruit teas and in rose hip tea. Antimutagenicity of tea extracts was tested by in vitro test using Saccharomyces cerevisiae D7 yeast. High antimutagenic activity showed mainly nettle tea, tutsan tea and most of fruit teas. During long-term storage (1 year, 20°C, darkness) a significant decrease of all analyzed antioxidant parameters was followed. Higher lost of antioxidants was found in fruit teas when compared with the herbal ones.
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