Extraction of Muriella decolor lipids using conventional and pressurized solvents and characterization of their fatty acid profile for biodiesel applications

Abstract

Microalgae have been described as a sustainable feedstock for biodiesel production. In this work, Muriella decolor lipids were extracted using pressurized (compressed propane, scCO2 and scCO2 followed by scCO2+ethanol) and conventional solvents (hexane, ethanol and chloroform:methanol). Total fatty acid methyl esters (FAMEs) in the unextracted biomass and solvent extracts were quantified and their profiles were determined by gas chromatography. Hexane was more selective for saponifiable lipids, whereas ethanol and chloroform:methanol resulted in higher yields of crude extracts. Among compressed fluids, propane led to both higher extraction yield and higher selectivity for saponifiable lipids, leading to 67.5% of the total FAME yield of hexane extracts. Sequential extractions using scCO2 followed by three stages of scCO2+EtOH improved extraction yields, reaching values (16.37 wt.% for a total FAME yield of 5.87 wt.%) higher than those obtained by conventional solvents. However, the selectivity for saponifiable matter decreased from the first extraction step.