Alternative Solvents for the Biorefinery of Spirulina: Impact of Pretreatment on Free Fatty Acids with High Added Value

Abstract

The growing demand for molecules of interest from microalgal biomass, such as phycobiliproteins, has led to an accumulation of unused by-products. For example, phycocyanin, obtained by the extraction of Spirulina, generated cakes rich in non-polar molecules of interest, such as free fatty acids (FFAs). These FFAs were generally considered as markers of lipidome degradation, but represented a relevant alternative to topical antibiotics, based on a biomimetic approach. In order to develop a sustainable Spirulina biorefinery scheme, different pretreatments and alternative solvents were screened to identify the best combination for the valorization of FFAs. Thus, five pre-treatments were studied including a phycocyanin extraction by-product. The following three biobased solvents were selected: ethyl acetate (EtOAc), dimethyl carbonate (DMC) and a fatty acid-based natural deep eutectic solvent (NaDES). The pigment and fatty acid profiles were established by spectroscopic and chromatographic approaches. NaDES demonstrated superior extraction capacity and selectivity compared to other biobased solvents, regardless of pretreatment. In contrast, EtOAc and DMC showed a greater diversity of FFAs, with a predominance of polyunsaturated fatty acids (PUFAs). The by-product has also been highlighted as a relevant raw material facilitating the recovery of FFAs. These results pave the way for a green biorefinery of the lipid fraction and phycobiliproteins of microalgae.

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

“…First UAE was explored to extract FFA using the three selected NaDES PC8, PC8C10 and OC8. UAE was already described as a green and relevant technology to extract FFA from spirulina cakes using conventional solvent [3].…”

“…For example, Spirulina (Arthrospira platensis) or Porphyridium cruentum were extracted for their high content of phycobiliproteins (phycocyanin and phycoerythrin, respectively) [1]. Phycobiliproteins (PBP) are highly promising metabolites exhibiting antioxidant, anti-cancer and anti-inflammatory activity [2][3][4]. The growing demand of phycobiliprotein-concentrated product in food market led to the extraction of increasing amount of microalgal biomass, using water as the main Disclaimer/Publisher's Note: The statements, opinions, and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s).…”

“…FFA are generated during PBP extraction by lipidome degradation due to intense thermal and agitation treatment, explaining that they are usually considered as lipidome degradation indicator in biofuel production. FFA are still industrially extracted using toxic solvents such as chloroform/methanol or hexane/methanol mixture, but greener alternatives were recently described like Natural Deep Eutectic Solvents (NaDES) [3,13,14].…”

“…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]. Fatty acid based NaDES, especially (C9/C10/C12, 3:2:1, mol/mol/mol), were reported as solvent with high capacity of FFA solubilization, but were highlighted as more specific of saturated FFA [3,14].…”

“…Our group have recently reported the extraction of FFA from fresh spirulina biomass using a panel of NaDES [3,13,14]. Fatty acid based NaDES, especially (C9/C10/C12, 3:2:1, mol/mol/mol), were reported as solvent with high capacity of FFA solubilization, but were highlighted as more specific of saturated FFA [3,14]. Fatty acid-based DES were also reported as potential antimicrobial media for drugs vectorization [28].…”