Optimum Ultrasound Assisted Extraction Conditions of Some Flavonoids from Green Tea Leaves. Control Quality of Green Tea Product by TLC Fingerprinting

摘要

The optimization of the green tea flavonoid extraction conditions was investigated. The experiments were carried out with two extraction methods: ultrasound assisted extraction (UAE) and reflux extraction (RE). The parameters that were varied in this study were: the extraction solvent system composition, the type of organic modifier of the extraction mixture, temperature, and time. The highest efficiency was obtained with an extraction mixture of ethanol: water, 80:20, v/v. An extraction performed at temperature of 45°C in 50-60 minutes led to optimum results. Moreover, a new fingerprinting procedure based on thin layer chromatography (TLC) image analysis was employed in order to compare the chemical composition of green tea in comparison with white and black tea.