Effective Antarctic krill oil extraction using switchable hydrophilicity solvents

Antarctic krill has been widely studied because of its abundant biomass, rich nutritional value, and great production potential. Notably, krill oil (KO) is rich in phospholipids (PLs), polyunsaturated fatty acids (PUFAs), and astaxanthin. A method based on a green switchable hydrophilicity solvent N,N-dimethylcyclohexylamine (DMCHA), which can reversibly change from oil soluble to water soluble in the presence of CO2 was used to extract KO from frozen Antarctic krill as it consumes less energy than traditional methods. We showed that DMCHA destroyed the surface structure of Antarctic krill and accelerated the dissolution of KO. In addition, this method enabled the PL extraction to reach up to 80.2% of total PLs, among which PC accounted for the highest proportion, up to 90.91% in PL. In fact, the astaxanthin extraction reached up to 81.44% of total astaxanthin while the fatty acid (FA) extraction up to 84.35%. The KO extracted through DMCHA was rich in PUFA, up to 47.74%, and the content of EPA + DHA reached 42.16% of total FA content. Furthermore, the amount of residual solvent in the lipid phase was just 0.23% of the DMCHA used for the extraction and the recovery rate of solvent was up to 93.2%. Our results demonstrated the high efficiency of oil extraction and the environmental friendliness of this method.