J Chromatogr A. 2011 Aug 26;1218(34):5765-73. doi: 10.1016/j.chroma.2011.06.088. Epub  2011 Jul 3.
 Pressurized liquid extraction of ginger (Zingiber officinale Roscoe) with bioethanol: an efficient and sustainable approach.
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Department of Molecular Biology, Aarhus University, Gustav Wieds Vej 10, 8000 Aarhus, Denmark.Abstract
To  develop an efficient green extraction approach for recovery of  bioactive compounds from natural plants, we examined the potential of  pressurized liquid extraction (PLE) of 
ginger  (Zingiber officinale Roscoe) with bioethanol/water as solvents. The  advantages of PLE over other extraction approaches, in addition to  reduced time/solvent cost, the extract of PLE showed a distinct  constituent profile from that of Soxhlet extraction, with significantly  improved recovery of diarylheptanoids, etc. Among the pure solvents  tested for PLE, bioethanol yield the highest efficiency for recovering  most constituents of gingerol-related compounds; while for a broad  concentration spectrum of ethanol 
aqueous  solutions, 70% ethanol gave the best performance in terms of yield of  total extract, complete constituent profile and recovery of most  gingerol-related components. PLE with 70% bioethanol operated at 1500  psi and 100 °C for 20 min (static extraction time: 5 min) is recommended  as optimized extraction conditions, achieving 106.8%, 109.3% and 108.0%  yield of [6]-, [8]- and [10]-gingerol relative to the yield of  corresponding constituent obtained by 8h Soxhlet extraction (absolute  ethanol as extraction solvent)