Extraction of unsaturated fatty acids from Aurantiochytrium sp. using amino acid-based deep eutectic solvents

This study used an amino acid-based deep eutectic solvent (DES) to extract unsaturated fatty acids, including docosapentaenoic acid and docosahexaenoic acid, from the microalga Aurantiochytrium sp. Microalgae represent valuable biological resources with diverse applications in fields such as biofuels, nutritional supplements, and cosmetics. Efficient methods for extracting unsaturated fatty acids from microalgae are thus desired. To address this need, DESs, which have attracted attention as environmentally benign solvents, were evaluated as extraction media. By combining various hydrogen bond acceptors and hydrogen bond donors to form DESs, proline/1,3-butylene glycol (ProBG) was found to provide the highest extraction yield. When the effect of the HBA:HBD molar ratio in ProBG was examined, a 1:3 molar ratio resulted in a further increase in extraction yield. To elucidate the factors underlying the differences in extraction yield, the polarity and viscosity of the solvents were measured and analysed.