Ginger (Zingiber officinale R.) extracts obtained using supercritical CO2 and compressed propane: Kinetics and antioxidant activity evaluation

This work reports the extraction of ginger (Zingiber officinale Roscoe) roots using sub and supercritical CO2 and compressed propane as solvents. Antioxidant activity effect and phenolic content were evaluated on the extracts obtained. The extractions were performed in a laboratory scale unit at pressures of 8.0 MPa, 16.5 MPa and 25.0 MPa using CO2 and 3.0 MPa, 6.5 MPa and 10.0 MPa using propane, and at 293.15 K, 313.15 K and 333.15 K for both solvents. The operating conditions tested achieved a maximum yield of 3.21 wt% for the CO2 extraction and 2.75 wt% for the extraction using propane as solvent. When CO2 was used as solvent, the pressure and temperature presented significant effect on the extraction yield. When propane was used, the most important variable was the pressure that presented a positive effect on the extraction yield. The chemical profiles were determined by gas chromatography and were similar for the two solvents, in which the main compounds were α-zingiberene, β-sesquiphellandrene, α-farnesene, geranial, β-bisabolene and β-eudesmol. The antioxidant activity assays were performed on the extracts obtained using the phosphomolybdenum reducing method. The extracts obtained using supercritical CO2 and compressed propane presented antioxidant effects. The highest antioxidant activity (931.67 ± 2.51 mg of α-tocopherol/g of extract) was found for extracts obtained using supercritical CO2 as solvent at 313.15 K and 16.5 MPa.

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► Ginger extracts with high antioxidant activity were obtained with scCO2 and propane.
► Chemical profiles found were similar for the two solvents.
► Propane can be used as an alternative compressed solvent for ginger extraction.