Maritime pine bark, an abundant Portuguese residue rich in high-value phenolic compounds, was subjected
to fractionated and non-fractionated high pressure extractions (F-HPE and NF-HPE, respectively).
Supercritical carbon dioxide (scCO2) was the chosen solvent to extract the pine bark low-polarity fraction
and ethanol (EtOH) was added to scCO2 to recover the phenolic fraction. The effect of the solvent flow rate
was studied on first step (scCO2) and second step (CO2:EtOH 90:10, v/v) F-HPE kinetics. Due to the low
first step yield (0.6–1.0%, d.b.) HPE was further performed with no fractionation at 303 K and
∼25 MPa.
The flow rate that achieved the highest global yield (7.6
×10−5 kg/s) was chosen to carry out NF-HPE with
different EtOH compositions (30–90%, v/v). The HPE results were compared with hydrodistillation and
Soxhlet extraction results in terms of global yields, extracts compositions and extracts antioxidant activities.
The results showed that fractionation, solvent flow rate and solvent composition affected extraction
kinetics and the characteristics of the extracts. In particular, the solvent composition CO2:EtOH (30:70)
led to the extract with the highest contents of total phenolic compounds and of procyanidins (25.6% and
19.8%, respectively), being similar to the ones achieved by Soxhlet extraction (26.0% and 18.2%, respectively).
The HPE methodology takes advantage over the conventional methodology due to the reduced
EtOH consumption, lower solvent-to-solid ratio, lower extraction temperature, and oxygen-free medium
in which it occurs.