Extraction of citronella grass solutes with supercritical CO2, compressed propane and ethanol as cosolvent: Kinetics modeling and total phenolic assessment

This study reports the experimental and kinetic modeling of citronella grass extraction by scCO(2), compressed propane, scCO(2) + ethanol, compressed propane + ethanol. Extraction yields were improved by adding ethanol as cosolvent for both compressed solvents. Kinetics and the extraction yield at equilibrium (Y-e) were in general investigated at the pressure range from 2 to 20 MPa at 20 degrees C, 40 degrees C and 60 degrees C. At temperature of 40 degrees C and similar pressures, propane was advantageous over CO2 in terms of the both kinetic paremeters k (increased from 4.1 +/- 0.5 s(-1) to 7.3 +/- 0.7 s(-1)) and Y-e (increased from 2.35 +/- 0.08% to 3.76 +/- 0.09%). Moreover, using compressed propane + ethanol both extraction parameters (k = 16 +/- 4 s(-1) and Y-e = 6.3 +/- 0%) were further improved. The total phenolic content was similar for all extracts evaluated at different extraction conditions and methods, except for the extract obtained by hydrodistillation, where higher value was obtained (1.4 +/- 0.4 mg GAE g(-1)) when compared to compressed solvents.