Isolation of the sweet components from Siraitia grosvenorii

Powdered concentrate from dried Luo Han Guo fruit was subjected to liquid extraction by Soxhlet (hexane:ethanol, 1/4 v/v) or with subcritical water (scH(2)O) or with supercritical ethanol carbon dioxide (scCO(2)). Whereas exhaustive Soxhlet extraction of the crude dried fruit powder (CDFP) was inefficient, pressurized water extraction in the presence of chromatographic support (Alumina, Celite or Silica gel) was beneficial to the scH(2)O recovery of mogrosides as determined by colourimetry. With a flow rate of 0.7 mL min(-1) scH(2)O and a back pressure of 11.7 MPa, a maximum recovery was obtained at 150 degrees C yet increases in recovery for extractions beyond 10 min were marRinal. The recovery of target compounds were very inefficient for scCO(2) alone but was improved with the addition of 0.3 mL min(-1) ethanol as co-solvent to the mobile phase and by adding chromatographic support to the substrate. Increased pressure during the scCO(2) extractions were beneficial to the recoveries that were maximized at 60 degrees C. However, increases in the recoveries of mogrosides for extractions beyond 90 min for the dried fruit powder or beyond 30 min for the partially purified concentrate were very modest. Of the three extraction techniques, Soxhlet, scCO(2) or scH(2)O the latter technique, in tandem with ultra-sonication of the dried fruit powder proved to be very efficient so that there was little value to partially purifying this substrate prior to pressurized fluid extraction. (c) 2007 Elsevier Ltd. All rights reserved.