Caffeine extraction from green tea leaves assisted by high pressure processing

A new method using high pressure processing to extract caffeine from green tea leaves was studied. The effect of different parameters such as high hydrostatic pressure (100-600 MPa), different solvents (acetone, methanol, ethanol and water), ethanol concentration (0-100% mL/mL), pressure holding time (1-10 min) and liquid/solid ratio (10:1 to 25:1 mL/g) were studied for the optimal caffeine extraction from green tea leaves. The highest yields (4.0 +/- 0.22%.) were obtained at 50% (mL/mL) ethanol concentration, liquid/solid ratio of 20:1 (ml/g), and 500 MPa pressure applied for 1 min. Experiments using conventional extraction methods (extraction at room temperature, ultrasonic extraction and heat reflux extraction) were also conducted, which showed that extraction using high pressure processing possessed several advantages, such as higher yields, shorter extraction times and lower energy consumption. (C) 2009 Elsevier Ltd. All rights reserved.