Extraction was carried out in a dynamic supercritical
fluid extractor unit (Water’s instrument, SuperParticle
SAS200 System) comprising a 2-L cylinder extraction cell
and a separator of 0.5-L capacity, with independent
temperature and pressure control. A co-solvent pump
was connected to the extraction line in order to supply the
modifier (organic solvent at high pressure) at a preestablished
flow rate, to be mixed with the CO2 flow before
reaching the extraction vessel. Ethanol (purity 96%, VWR
international) was used as a co-solvent. Briefly, the
extraction procedure consisted in placing 170 g of blackcurrant
bud finely ground and dried inside the extractor to
form the fixed bed of particles, followed by the control of
the process variables (temperature, pressure and solvent
flow rate, Fig. 2).
The assays were conducted in similar temperature and
flow rate conditions. The extractions were performed at
35 8C and a constant flow rate of 20 g/min. The first
extraction was performed at a constant pressure of 100 bar
and the second extraction was carried out at a constant
pressure of 200 bar. The co-solvent was separated from the
solute using low-pressure methods (separators at 0 8C).
The samples recovered were solid and pasty. In order to
ensure an accurate determination of extraction yield with
time, the separator was washed with ethanol and the
residual material recovered in each case was mixed with