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Chemical Engineering and Processing, Vol.42, No.2, 129-133, 2003
Microwave-assisted extraction of tea polyphenols and tea caffeine from green tea leaves
A microwave-assisted extraction (MAE) method is presented for the extraction of tea polyphenols (TP) and tea caffeine from green tea leaves. Various experimental conditions. such as ethanol concentration (0 - 100%, v/v), MAE time (0.5 - 8 min), liquid/solid ratio (10:1 - 25:1 ml g(-1)), pre-leaching time (0-90 min) before MAE and different solvents for the MAE procedure were investigated to optimize the extraction, The extraction of tea polyphenols and tea caffeine with MAE for 4 min (30 and 4%) were higher than those of extraction at room temperature for 20 h. ultrasonic extraction for 90 min and heat reflux extraction for 45 min (28 and 3.6%), respectively. From the points of extraction time, the extraction efficiency and the percentages of tea polyphenols or tea caffeine in extracts, MAE was more effective than the conventional extraction methods studied.