Extraction Of Antarctic Krill (Euphausia Superba) Oil Including Astaxanthin By Supercritical Carbon Dioxide

The technology of supercritical carbon dioxide （SC-CO₂）extraction of Antarctickrill （Euphausia superba） oil was studied.With the extraction yield of krill oil as theevaluation index, the extraction processby SC-CO₂was optimized. The results showedthat the optimum extraction condition for maximizingoil yieldas follows: extractiontemperature at60°C, extraction pressure under40MPa, static extraction for30min anddynamic extraction for120min. Under these parameters of extraction,the oil yield ofdried Antarctic krill and frozen Antarctic krill blocks were86.18±1.38%and84.07±3.58%, respectively. Krill oil extracted by SC-CO₂was compared withthecommonly extracted by organic solven. The results showed that the extraction yieldof krill oil bySC-CO₂was higher than that by organic solvent. Therefore, theSC-CO₂extraction method is more suitable for extraction of krill oil.A rapid and simple method was developed for the determination of volatiles fromAntarctic krill oil by using headspace solid-phase micro-extraction （HS-SPME）coupledto gas chromatography-mass spectrometry （GC-MS）. The optimum extractionconditions were obtained as follows:75μm CAR/PDMS fiber,exposure for50min at45°C, and desorption for5min at250°C.Under these conditions, HS-SPME methodwas effective to extract the volatiles inAntarctic krill oil; a total of35compoundswereidentified and the content of decane （11.99%） was highest. In this paper, krill oilwas extraction by SC-CO₂and organic solvent from dried Antarctic krill and frozenAntarctic krill blocks, respectively. The physicochemical properties and fatty acidsprofiles of krill oil were studied. The results showed that krill oil had a variety of kindsof fatty acids with high contents of unsaturated fatty acids （UFA）. The krill oil extractedfrom frozen Antarctic krill blocks contained higher contents of polyunsaturated fattyacids （PUFA）, EPA （C20:5n-3）, n-3PUFA and n-3/n-6PUFA than those extracted fromdried Antarctic krill by the same extraction method. Compared with organic soven method, SC-CO₂method had better effects on keeping the quality of krill oil, especiallyon retaining polyunsaturated fatty acids.Carotenoids were extracted from Antarctic krill and analyzed by thin layerchromatography （TLC） combined with high performance liquid chromatography（HPLC） method. And the contents of carotenoids were determined by theultraviolet（UV）spectrophotometer; the content of astaxanthin was identified by usingthe HPLC. The results showed that the contents of carotenoids and astaxanthin in frozenAntarctic krill blocks were4.80±0.08mg/100g （dry weight） and0.80±0.04mg/100g （dryweight）. TheSC-CO₂technology of astaxanthin was investigated to extract theastaxanthin. With the extraction yield of astaxanthin as the evaluation index, theextraction process was optimizedby SC-CO₂combined with the HPLC.The extractionconditions, including extraction pressure, temperature and the concentration of entrainer（absolute ethyl alcohol） were investigated by stepwise regression analysis. The modelwas Y=4.896+4.984A+0.952C.The results showed that the concentration of entrainer（A） and extraction pressure（C） had significant effects on the extracion yield ofastaxanthin （P<0.05）. The optimum extraction condition for astaxanthin yield withinthe experimental range of the variables was for40MPa as extraction pressure,45°C asextraction temperature,1.00mL/g as the concentration of entrainerand with3.5hextraction. Using these parameters, the yield was predicted to be87.96%.In this paper, the technology of SC-CO₂methodfor extracting Antarctic krill oil wasstudied. The extraction conditions for oil yield wereoptimized. The volatilecompositions of Antarctic krill oil were identified and determined. The quality and fattyacid compositions of krill oil extracts were studied. Futhermore, astaxanthin wasextracted by SC-CO₂in this paper. This study could providetheoretical basis for krill oilextraction in the idustrialized large-scale and has guiding significance fordeep-processing of Antarctic krill products.