title: 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.
authors.affiliation: School of Mechanical & Automotive Engineering, South China Univ. of Technology, Guangzhou, 510640, China. wqtang@scut.edu.cn
authors.forename: Wei-Qiang
authors.initials: WQ
authors.lastname: Tang
authors.forename: Di-Cai
authors.initials: DC
authors.lastname: Li
authors.forename: Yang-Xiao
authors.initials: YX
authors.lastname: Lv
authors.forename: Jian-Guo
authors.initials: JG
authors.lastname: Jiang
mesh_terms: D000465:Algorithms; D000704:Analysis of Variance; D002110:Caffeine / Q000032:analysis / Q000737:chemistry*; D028241:Camellia sinensis / Q000737:chemistry; D002245:Carbon Dioxide; D002851:Chromatography, High Pressure Liquid; D025924:Chromatography, Supercritical Fluid / Q000379:methods*; D005419:Flavonoids / Q000032:analysis; D005511:Food Handling / Q000379:methods*; D055951:Functional Food / Q000032:analysis; D006358:Hot Temperature; D007700:Kinetics; D010636:Phenols / Q000032:analysis; D018515:Plant Leaves / Q000737:chemistry; D059808:Polyphenols; D011312:Pressure; D015203:Reproducibility of Results; D013010:Sonication; D013056:Spectrophotometry, Ultraviolet; D013662:Tea / Q000737:chemistry*; D014465:Ultrasonics; D014867:Water / Q000032:analysis
chemical_list: D005419:Flavonoids; D010636:Phenols; D059808:Polyphenols; D013662:Tea; D014867:Water; D002245:Carbon Dioxide; D002110:Caffeine