Simultaneous extraction of DHA‐ and EPA‐rich oil and separation of proteins from Antarctic krill using three‐phase partitioning system of cosolvents and organic salt

Abstract BACKGROUND The nutritional and functional potential of eicosapentaenoic acid (EPA)‐ and docosahexaenoic acid (DHA)‐rich oil from Antarctic krill has continued to attract attention worldwide. Therefore, a highly effective approach is essential for extracting Antarctic krill's DHA/EPA‐rich oil and proteins from wet biomass in the same system. RESULTS A cosolvent three‐phase partitioning system (TPPS) was developed to simultaneously extract DHA/EPA‐rich oil and separate proteins (PT) from wet Antarctic krill ( Euphausia superba ) biomass. The COSMO‐RS was used to screen cosolvents for the extraction of EPA and DHA. The TPPS parameters were optimized by response surface methodology using a central‐composite design, which consisted of 52% (w/w) of cosolvents (t‐butanol:n‐hexane (4:6)), 20% (w/w) of ammonium citrate, 500 rpm of stirring speed, 37 °C of temperature, and 60 min of extraction time. Under the optimized conditions, the extraction efficiency of EPA and DHA was 95.36 ± 0.94% and 93.85 ± 1.31% in the top cosolvents phase, respectively, as well as 86.57 ± 0.98% of proteins in the middle interface. Compared to supercritical CO 2 (SCO 2 ) and three‐liquid‐phase salting‐out extraction system (TLPSOES), the recovery rate of krill oil (KO) extracted by TPPS (96.48 ± 1.14%) was much higher than that of the SCO 2 (67.8%) and of the TLPSOES method (91%). CONCLUSION This study demonstrates that cosolvent TPPSs can extract krill oil from wet krill biomass with higher extraction efficiency, and that the obtained krill oil showed potential antioxidant effects compared to commercial fish oil. Therefore, the cosolvent TPPS could be an alternative in the nutraceutical industry. © 2022 Society of Chemical Industry (SCI).