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

Abstract

In this article, microalgae Nannochloropsis sp. was used for fatty acid (FA) extraction, using a supercritical fluid-carbon dioxide (SF-CO2) extraction method. This study investigated the influence of different pre-treatment conditions by varying the grinding speed (200–600 rpm), pre-treatment time (2.5–10 min), and mixing ratio of diatomaceous earth (DE) and Nannochloropsis sp. biomass (0.5–2.0 DE/biomass) on FAs extraction. In addition, the effect of different operating conditions, such as pressure (100–550 bar), temperature (50–75 °C), and CO2 flow rate (7.24 and 14.48 g/min) on eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) recovery, was analyzed. Experimental data evidenced that, keeping constant the extraction conditions, the pre-treatment step enhanced the FAs extraction yield up to 3.4 fold, thereby the maximum extracted amount of FAs (61.19 mg/g) was attained with the pre-treatment with a ratio of DE/biomass of 1 at 600 rpm for 5 min. Moreover, by increasing both SF-CO2 pressure and temperature, the selectivity towards EPA was enhanced, while intermediate pressure and lower pressure promoted DHA recovery. The highest amount of extracted EPA, i.e., 5.69 mg/g, corresponding to 15.59%, was obtained at 75 °C and 550 bar with a CO2 flow rate of 14.48 g/min, while the maximum amount of extracted DHA, i.e., ~0.12 mg/g, equal to 79.63%, was registered at 50 °C and 400 bar with a CO2 flow rate of 14.48 g/min. Moreover, the increased CO2 flow rate from 7.24 to 14.48 g/min enhanced both EPA and DHA recovery.

Comparative Analysis of Far East Sikhotinsky Rhododendron (Rh. sichotense) and East Siberian Rhododendron (Rh. adamsii) Using Supercritical CO2-Extraction and HPLC-ESI-MS/MS Spectrometry

“…Supercritical fluid extraction (SFE) has been used since the late 1970s to analyze food products, isolate biologically active substances and determine lipid levels in food, as well as levels of toxic substances [ 19 , 20 , 21 ]. The use of SFE for fractionation and/or enrichment of certain components in products has been reported since the 1980s [ 22 , 23 , 24 ]. In addition, the products do not have residues of organic solvents, which occur with conventional extraction methods, and solvents can be toxic, for example, in the case of methanol and n -hexane.…”

Microwave-Assisted Brine Extraction for Enhancement of the Quantity and Quality of Lipid Production from Microalgae Nannochloropsis sp.

“…Although some of the abovementioned methods have many advantages, such as high extraction efficiency and energy-effective [15], most of the methods are not environmentally friendly due to use of toxic solvents. Others such as supercritical fluid extraction are more environmentally friendly, but dealing with a high extraction pressure resulted in higher energy consumption [20]. In addition, some methods display low yield due to extended extraction time, as well as cost ineffective due to high solvent and expensive enzyme usages.…”

Recent advances of green pretreatment techniques for quality control of natural products

“…Leone et al applied supercritical CO 2 extraction to extract ω-3 fatty acids from Nannochloropsis sp. selectively [74]. Various kinds of oils [75][76][77][78][79][80] and phenolic compounds [81][82][83][84][85][86] in NPs, which have certain activities, were also could be extracted effectively by CO 2 SFE when the related factors were optimized.…”