Eicosapentaenoic Acid Extraction from Nannochloropsis gaditana Using Carbon Dioxide at Supercritical Conditions

Abstract

This research shows that carbon dioxide supercritical fluid (CO2-SF) is an emerging technology for the extraction of high interest compounds for applications in the manufacturing of pharmaceuticals, nutraceuticals, and cosmetics from microalgae. The purpose of this study is to recover fatty acids (FAs) and, more precisely, eicosapentaenoic acid (EPA) from Nannochloropsis gaditana biomass by CO2-SF extraction. In the paper, the effect of mechanical pre-treatment was evaluated with the aim of increasing FAs recovery. Extraction was performed at a pressure range of 250–550 bars and a CO2 flow rate of 7.24 and 14.48 g/min, while temperature was fixed at 50 or 65 °C. The effect of these parameters on the extraction yield was assessed at each extraction cycle, 20 min each, for a total extraction time of 100 min. Furthermore, the effect of biomass loading on EPA recovery was evaluated. The highest EPA extraction yield, i.e., 11.50 mg/g, corresponding to 27.4% EPA recovery, was obtained at 65 °C and 250 bars with a CO2 flow rate of 7.24 g/min and 1.0 g biomass loading. The increased CO2 flow rate from 7.24 to 14.48 g/min enhanced the cumulative EPA recovery at 250 bars. The purity of EPA could be improved by biomass loading of 2.01 g, even if recovery was reduced.

Supercritical Fluid Extraction of Lutein from Scenedesmus almeriensis

“…Matrix solid-phase dispersion (MSPD) of microalgae biomass was carried out using a ball miller to enhance the extraction efficiency of intracellular compounds [19,24,27]. Therefore, the pretreatment conditions were optimized to enhance the recovery of lutein from S. almeriensis .…”

“…The optimum stirring rate provides the effective mechanical force, which leads to homogenously break the microalgae cell. Therefore, the degree of MSPD needs to be optimized for each microalga due to their varied chemical composition of intracellular molecules and the cell wall structure of microalgae biomass [24,26]. In the second step, the pre-treatment time (2.5–10 min) was optimized to enhance the lutein recovery at 400 rpm with 0.4 DE/biomass ratios.…”

“…The literature proposes different lutein extraction technologies from S. almeriensis but the findings are not sufficient to establish a clear methodological and a defined approach for the evaluation of extraction costs, yield, and quality of the final extracts [19,20,21,22,23,24,25,26].…”

Selective Extraction of ω-3 Fatty Acids from Nannochloropsis sp. Using Supercritical CO2 Extraction

“…The experimental data showed that the maximum recovery of astaxanthin and lutein could be achieved at low temperature and high pressure (50 °C and 550 bar, respectively) adopting the lowest investigated CO 2 flow rate (3.62 g/min), while a higher flow rate (14.48 g/min) increased astaxanthin and lutein purities. Molino et al [20] studied the effect of extraction pressure (250, 400 and 550 bars) and temperature (50 and 65 °C) at CO 2 flow rates of 7.24 and 14.48 g/min for EPA recovery from Nannochloropsis gaditana biomass during SF-CO 2 extraction, resulting in a maximum EPA recovery of 27.4% at 65 °C and 250 bars with a CO 2 flow rate of 7.24 g/min.…”

“…The flow rate of CO 2 defines the residence time for the contact between the solute and the solvent, which have various effects on the selectivity of bioactive compounds and extraction efficiency. To the best of authors’ knowledge, only a few reports in the literature on the role of CO 2 flow rate on the selectivity of bioactive compounds and extraction efficiency exist [16,17,20,21,22]. Machmudah et al [22] investigated the effect of CO 2 flow rate (2–4 mL/min) at 50 MPa and 50 °C for astaxanthin recovery from H. pluvialis , and they found that the amount of total extract could be increased, whereas the amount of astaxanthin in the extract almost remained unchanged.…”