Three‐liquid‐phase salting‐out extraction of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA)‐rich oils from Euphausia superba

Abstract

The TLPSOES parameters were optimized by response surface methodology using Box–Behnken design, which were 16.5% w/w of ammonium citrate, 17.5% w/w of ethanol, and 46% w/w of n‐hexane at 70 min of stirring time. Under optimized conditions the extraction efficiency attained was 90.91 ± 0.97% of EPA, 90.02 ± 1.04% of DHA, and 91.85 ± 1.11% of KO in the top n‐hexane phase. The highest extraction efficiency of proteins and flavonoids, i.e. 88.34 ± 1.35% and 79.67 ± 1.13%, was recorded in the solid interface and ethanol phase, respectively. The KO extracted by TLPSOES system consisted of lowest fluoride level compared to the conventional method and whole wet krill biomass. The TLPSOES is a potential candidate for nutraceutical industry of KO extraction from wet krill biomass.

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

“…The extraction efficiency of proteins was 86–87% in the TPPS comprised of wet krill biomass, ammonium citrate, and n‐hexane:t‐butanol. The ammonium citrate formed a clear TLPSOES; 27 therefore, it was chosen to optimize the cosolvent TPPS. Table 2 and Fig.…”

“…The wet E. superba biomass was provided by Dalian Ocean Fishery Group Corporation and stored at −70 °C. The wet biomass was analyzed for total amounts of oils (2.87 ± 1.43%), EPA in oil (12.47 ± 1.69%), DHA in oil (8.62 ± 1.28%), and proteins (13.95 ± 1.24%) w/w 27 . The standard of heptadecanoic acid, EPA, and DHA were purchased from Sigma‐Aldrich (purity greater than 99%).…”

“…The SCO 2 operating temperature and time were controlled at 45 °C and 120 min, respectively. 27 The TLPSOES parameters consisted of 16.5% (w/w) of ammonium citrate, 17.5% (w/w) of ethanol, and 46% (w/w) of n-hexane. The salt, wet krill, and water were added into a tube and vortexed for 3-4 min.…”

“…The cosolvents mixture can dissolve more EPA and DHA due to its hydrophobicity 26 . At the same time, ammonium citrate can improve the accumulation of the proteins to the middle interface and reduce fluoride concentration in the DHA‐rich oil and proteins 27 . Previously, the krill oil was extracted by a single solvent, supercritical CO 2 (SCO 2 ), and three‐liquid‐phase salting‐out extraction system (TLPSOES) 18,27 .…”

“…27 Previously, the krill oil was extracted by a single solvent, supercritical CO 2 (SCO 2 ), and threeliquid-phase salting-out extraction system (TLPSOES). 18,27 Although the krill oil extraction yield was not the highest, long extraction duration was another challenge. Both issues were successfully addressed in the cosolvent TPPS, which achieved the highest extraction efficiency and reduced extraction duration.…”