Cistus creticus is a species of the Cistus family that exhibits a wide range of bioactivities; therefore, its oil recovery using a green extraction method is of significant importance for both academic research and industrial applications. Thus, the objective of this work is cistus oil recovery by supercritical fluid extraction (SFE) with CO2. To this end, the effect of various process parameters, namely extraction pressure (110–250 bar), extraction temperature (40–60 °C), and solvent flow rate (1–3 kg/h), on the yield of the process was examined. It was shown that an increase in temperature, and particularly in pressure, positively affects the yield, while the flow rate increase mainly enhances the extraction rate. Hence, the highest yield (8.58% wt) was obtained at 60 °C, 250 bar, and 3 kg/h after 150 min of extraction. Furthermore, the experimental data regarding the kinetics of SFE were correlated successfully by a mass balance model based on Lack’s plug flow model. In addition, the comparison of SFE extracts obtained under intermediate conditions with the essential oil produced by hydrodistillation revealed the extraction of heavier compounds, notably a high content of linoleic acid. Finally, the addition of a small amount of co-solvent (5% wt ethanol) to the SFE process enhanced yield (9.53% wt) as well as antioxidant activity (IC50 = 95.4 mgextract/mL) and total phenolic content of the extract (23.2 mgGAE/gextract). Thus, SFE could become a promising alternative to conventional extraction with ethanol, which exhibited the highest yield (28.5% wt) and a high antioxidant activity (IC50 = 3.2 mgextract/mL), given SFE’s shorter extraction duration.
Chiliou et al. (Sat,) studied this question.