Production of a food grade extract of Chlorococcum amblystomatis rich in omega-3 lipids using ethanol assisted with ultrasound and deep characterization by lipidomics

Chlorococcum amblystomatis is a novel microalga with a high content of omega-3 fatty acids (FAs), with applications for food, feed, nutraceuticals, and biotechnology. These applications require the use of food-grade green solvents such as ethanol (EtOH) for lipid extraction, which can be associated with lower lipid recovery yields if not assisted with mechanical means. Ultrasonication can increase the recovery of lipids and omega-3 FAs, however, the impact on polar lipids remains poorly understood. In this study, we propose a comparative lipidomic analysis through liquid-chromatography mass spectrometry (LC–MS) of extracts obtained with EtOH combined with ultrasound-assisted extraction (UAE) and conventional extraction with dichloromethane:methanol (DCM) or EtOH. Extraction with UAE improved the recovery yield of EtOH alone from 2.3 ± 0.3 to 14.6 ± 0.6%, which is comparable to lipid recovery from DCM (16.7 ± 0.8%). The fatty acid profile of UAE extracts showed no differences in comparison with DCM. Lipidomic LC–MS/MS analysis showed that UAE allowed lipid extracts rich in polar lipids containing omega-3 PUFAs with lipid yield and lipid profile similar to DCM to be obtained. Taken together these results demonstrate the effectiveness of UAE in obtaining extracts rich in omega-3 glycolipids and phospholipids from C. amblystomatis for different biotechnological applications.