Effect of mass transfer on the removal of caffeine from green tea by supercritical carbon dioxide

Hyong Seok Park, Hyung Kyoon Choi, Sung-Joon Lee, Kwon Woo Park, Sung Gil Choi, Kyoung Heon Kim

Research output: Contribution to journalArticle

60 Citations (Scopus)

Abstract

To remove caffeine from green tea, supercritical CO2 (SC-CO2) extraction using 95% (v/v) ethanol as a modifier was carried out on a laboratory scale in the ranges of 150-300 bar and 50-80 °C. The extraction yield of caffeine and catechins including epigallocatechin gallate (EGCG) increased with an increase in temperature at a constant pressure, and also increased with increasing pressure at a fixed temperature. When the CO2 mass flow rate increased, the total extraction yield of caffeine and catechins also increased, but the extraction efficiency of CO2, which was determined by the amount of the solutes extracted per amount of CO2 used, decreased, possibly due to the negligible effect of external mass transfer resistance around green tea particles and the reduced contact time for SC-CO2 and green tea. The reduction of green tea particle size by grinding also resulted in the enhanced extraction of caffeine and catechins, which indicates the larger particle size yielded the slower extraction rate. These results gave rise to the conclusion that internal mass transfer resistance is predominant over the external mass transfer resistance in the extraction of green tea by SC-CO2 like other herbaceous materials. In addition to the extraction of caffeine, the substantial amount of catechins was also found to be extracted during the decaffeination processes.

Original languageEnglish
Pages (from-to)205-211
Number of pages7
JournalJournal of Supercritical Fluids
Volume42
Issue number2
DOIs
Publication statusPublished - 2007 Sep 1

Fingerprint

Caffeine
caffeine
Carbon Dioxide
mass transfer
carbon dioxide
Carbon dioxide
Mass transfer
Catechin
Particle size
gallates
Tea
mass flow rate
grinding
solutes
Ethanol
ethyl alcohol
Flow rate
Temperature
temperature

Keywords

  • Caffeine
  • Catechins
  • Decaffeination
  • Green tea
  • Supercritical carbon dioxide

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Materials Science (miscellaneous)
  • Physics and Astronomy (miscellaneous)

Cite this

Effect of mass transfer on the removal of caffeine from green tea by supercritical carbon dioxide. / Park, Hyong Seok; Choi, Hyung Kyoon; Lee, Sung-Joon; Park, Kwon Woo; Choi, Sung Gil; Kim, Kyoung Heon.

In: Journal of Supercritical Fluids, Vol. 42, No. 2, 01.09.2007, p. 205-211.

Research output: Contribution to journalArticle

Park, Hyong Seok ; Choi, Hyung Kyoon ; Lee, Sung-Joon ; Park, Kwon Woo ; Choi, Sung Gil ; Kim, Kyoung Heon. / Effect of mass transfer on the removal of caffeine from green tea by supercritical carbon dioxide. In: Journal of Supercritical Fluids. 2007 ; Vol. 42, No. 2. pp. 205-211.
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