Extraction of Nannochloropsis Fatty Acids Using Different Green Technologies: The Current Path

Abstract

Nannochloropsis is a genus of microalgae widely recognized as potential sources of distinct lipids, particularly polyunsaturated fatty acids (PUFA). These may be obtained through extraction, which has conventionally been performed using hazardous organic solvents. To substitute such solvents with “greener” alternatives, several technologies have been studied to increase their extraction potential. Distinct technologies utilize different principles to achieve such objective; while some aim at disrupting the cell walls of the microalgae, others target the extraction per se. While some methods have been utilized independently, several technologies have also been combined, which has proven to be an effective strategy. The current review focuses on the technologies explored in the last five years to extract or increase extraction yields of fatty acids from Nannochloropsis microalgae. Depending on the extraction efficacy of the different technologies, distinct types of lipids and/or fatty acids are obtained accordingly. Moreover, the extraction efficiency may vary depending on the Nannochloropsis species. Hence, a case-by-case assessment must be conducted in order to ascertain the most suited technology, or tailor a specific one, to be applied to recover a particular fatty acid (or fatty acid class), namely PUFA, including eicosapentaenoic acid.

Factors impacting the microbial production of eicosapentaenoic acid

“…Nowadays, there is a growing concern in finding alternative, less health and environmental hazardous, solvents (sometimes designated “green” solvents) to the traditionally utilized organic ones. Since, usually, such solvents present lower yields, distinct technologies are also being applied, in order to increase their extraction efficiencies (Sousa et al 2023b ). As for separation, there is also a panoply of technologies that can be utilized for the extraction lipids from cells, which also have advantages and disadvantages (Table 1 ), according to the technology and the mechanisms by which extraction is performed.…”

“…The aim of these technologies is to facilitate the access of the extraction solvent to the compound intended to extract. Generally, extraction technologies can be divided by the principle/mechanism by which they exert their action, and in this sense, technologies can be classified as being of physical (including mechanical), chemical, or enzymatic nature (Chen et al 2023 ; Sousa et al 2023b ; Ren et al 2022 ). Additionally, there are also some more “unconventional” methods.…”

“…Ultrasounds (sonication) and microwaves are two physical-based methods that are sometimes also classified as mechanical, since the phenomenon generated by these methods results in a “mechanical” force being exerted. In ultrasounds-assisted extraction, the propagation of the ultrasonic waves through the liquid creates bubbles which eventually collapse due to pressure differences (this phenomenon is designated cavitation), and the shear forces resulting from the bursting of the bubbles lead to the cellular rupture (Sousa et al 2023b ; Zhou et al 2022 ; Enamala et al 2018 ). Microwave-assisted extraction is based on the evaporation of water from the cells, due to heat generated by the application of the microwaves, which generates forces from within the cell and result in their rupture (Chen et al 2023 ; Mehariya et al 2021 ).…”

Integrated Process for Schizochytrium Oil Extraction, Enzymatic Modification of Lipids and Concentration of DHA Fatty Acid Esters Using Alternative Methodologies

“…For their extraction, modern technologies such as pressurized liquid extraction (PLE) arise as an alternative to traditional extraction procedures [16,17]. PLE uses high temperatures and pressures that can extract bioactive compounds extremely quickly, avoiding their oxidation and deterioration in a process that follows the principles of green chemistry [18][19][20][21][22]. Thus, the possibility of modifying these parameters enables the optimization of lipid extraction for its consequent hydrolysis by lipases.…”

Innovative Alkanediol-Based Eutectic Solvents for Extracting/Pre-Formulating Dermatologically Valuable Free Fatty Acids from Spirulina and <em>Porphyridium </em>Cakes

“…A set of HDES based on oleic acid and terpene, like thymol or geraniol, was also screened for asthaxanthin extraction from Haematococcus pluvialis [26]. Considering microalgae lipids, omega 3 lipid were recovered from Nannochloropsis using choline chloride-based DES but was focusing on ester lipid and not FFA [27]. Our group have recently reported the extraction of FFA from fresh spirulina biomass using a panel of NaDES [3,13,14].…”