Natural antioxidant fine particles recovery from Eucalyptus globulus leaves using supercritical carbon dioxide assisted processes

• SAS process led to successful precipitation of spherical micro particles of Eucalyptus compounds.
• SAS precipitates were more concentrated than the extract in several monoterpenes.
• Most of the SAS processed eucalyptus particles had stronger antioxidant activity than the unprocessed eucalyptus extract.

Supercritical antisolvent (SAS) processes were carried out to obtain precipitates from eucalyptus leaves with potent antioxidant activity. For that, an extract was previously obtained by supercritical fluid extraction (SFE) from these leaves using CO2 and ethanol as a solvent and co-solvent, respectively. Around fifty compounds were identified by gas chromatography-mass spectrometry (GC–MS) in the supercritical fluid extract and most of them were in the precipitates. The effects of different parameters on the outcome of the SAS process were analyzed such as temperature (35 and 50 °C), pressure (100 to 200 bar), CO2 flow rate (2 to 5 g/min), liquid flow rate (10 to 30 mL/min) and washing time (30 and 60 min). The antioxidant activities of both the supercritical fluid extract of eucalyptus and SAS precipitates were evaluated by DPPH assay. Most of the SAS precipitates of eucalyptus micro particles showed stronger antioxidant activity compared to the eucalyptus supercritical fluid extract.

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