Lipid and phycocyanin extractions from Spirulina and economic assessment

Microalgae are a promising feedstock for several bioproducts due to their low carbon footprint in cultivation and high biomass productivity. However, downstream processes such as oil extraction usually require the use of solvents harmful to health. This work evaluated lipid extraction from cyanobacteria Spirulina platensis using green solvents: supercritical CO2 (scCO2), high-pressure (HP) ethanol, and scCO2 with ethanol as a co-solvent (60 °C, 400 bar); compared to conventional lab-scale extractions: Soxhlet, Bligh & Dyer (B&D), and ultrasound-assisted extraction. Subsequent phycocyanin extraction was considered to improve economic performance. Total extract yield using B&D showed the highest value (11.6%), followed by HP ethanol (11.4%); nevertheless, scCO2 resulted in better selectivity for fatty acid content (0.57 g/ g lipids). Integrating lipid and phycocyanin extraction to a Spirulina facility is unprofitable in the considered conditions. However, utilization of CO2 from an emitter facility could provide a profitable scenario.