Fractioned SFE of antioxidants from maritime pine bark

Maritime pine (Pinus pinaster) is an important portuguese forest species and its bark is an abundant furniture industry residue. In this work, fractioned supercritical fluid extraction (FSFE) experiments were carried out using CO2 and CO2 + EtOH (10%) mixtures in two consecutive steps. Different pressures (from 10 up to 30 MPa) and temperatures (30, 40 and 50 °C) were assayed. FSFE extracts were compared with hydrodistillation (HD) and Soxhlet (SoE) extracts. Gas chromatography (GC) was used to characterize the obtained volatile oils while catechin and epicatechin were quantified in ethanolic extracts by HPLC. Antioxidant activities were determined spectrophotometrically. Around 84% of the total extract was obtained in the 1st CO2 extraction step and this volatile oil rich extract presented lower oxidation inhibitions (∼29–62%) than those obtained at the 2nd CO2 + EtOH extraction step (60–84%). The catechin + epicatechin yields of these 2nd step ethanolic extracts were higher (0.051–0.346 μg/mg d.b.) than the ones obtained for SoE (0.039 μg/mg d.b.). The increment in catechin + epicatechin extract content influenced the corresponding extract antioxidant activity, although not directly. Pressure and temperature affected the extraction kinetic parameters for both extraction steps and the obtained catechin + epicatechin contents for the 2nd CO2 + EtOH extraction step.The employed high pressure fractioned extraction methodology showed that it was possible to obtain different extract fractions having diverse antioxidant capacities from Pinus pinaster bark. Furthermore, this process can be further optimized in order to improve extraction yields, selectivities and antioxidant activities, by the use of different solvent mixtures compositions and of other different operational conditions. Therefore, the reuse of this abundant portuguese agroindustrial residue may originate several possible high-value extracts for different applications like, for example, the use the volatile oil fractions in the aroma/flavor industries, and/or the use of phenolic fractions in the food and pharmaceutical industries.