Extraction and Removal of Caffeine from Green Tea by Ultrasonic‐Enhanced Supercritical Fluid

Abstract

Low-caffeine or caffeine-removed tea and its products are widely welcomed on market in recent years. In the present study, we adopt ultrasonic-enhanced supercritical fluid extraction process to remove caffeine from green tea. An orthogonal experiment (L16 (4(5))) was applied to optimize the best removal conditions. Extraction pressure, extraction time, power of ultrasound, moisture content, and temperature were the main factors to influence the removal rate of caffeine from green tea. The 5 factors chosen for the present investigation were based on the results of a single-factor test. The optimum removal conditions were determined as follows: extraction pressure of 30 MPa, temperature at 55 degrees C, time of 4 h, 30% moisture content, and ultrasound power of 100 W. Chromatogram and ultraviolet analysis of raw material and decaffeinates suggests that under optimized conditions, the caffeine of green tea was effectively removed and minished without damaging the structure of active ingredients in green tea.

Antioxidant and Antimicrobial Activities of (‐)‐Epigallocatechin‐3‐gallate (EGCG) and its Potential to Preserve the Quality and Safety of Foods

“…Due to its high selectivity for CAF, this method has been tested in several studies to separate CAF from catechins (Huang, Wu, Chiu, Lai, & Chang, ; Kim, Kim, Kim, Oh, & Lee, ; Park et al., ). Tang, Li, Lv, and Jiang () used SCCO 2 as cosolvent with the aid of ultrasound. CAF recovery in their study was around 79%.…”

Comparison of extraction and isolation efficiency of catechins and caffeine from green tea leaves using different solvent systems

“…Green tea also contains about 1-5% caffeine (dry weight basis), which is considered to exert health problems, such as sleep deprivation and hypersensitivity (Hindmarch et al, 2000;Masdrakis et al, 2009). Several methods have been suggested to remove caffeine from green tea extracts, including organic solvents extraction, water extraction, supercritical carbon dioxide extraction, ultrasonic-enhanced supercritical fluid and recent microwave-enhanced vacuum ice water extraction (Perva-Uzunalic et al, 2006;Kim et al, 2008;Tang et al, 2010;Lou et al, 2012). In general, the decaffeination processes may reduce the amount of catechins in tea, so it might not provide the same health benefits as caffeinated green tea (Henning et al, 2003).…”

Optimization of Ultrasonic Extraction of Phenolic Antioxidants from Green Tea Using Response Surface Methodology

“…It is described that EGCG/Caffeine level was higher in ultrasound-assisted extraction by immersed ultrasonic bath than that in water extraction by heated magnetic stirrer. Tang also reported that ultrasonic-enhanced supercritical fluid extraction was effective at removing caffeine from green tea without damaging the structure of its active components [45]. However, this technique has some defects such as long extraction time (4 h) and high extraction pressure (30 MPa), resulting in high operating costs and limiting its large-scale industrial application.…”