Extraction of lipid from sea urchin (Strongylocentrotus nudus) gonad by enzyme-assisted aqueous and supercritical carbon dioxide methods

Abstract

As rich in polyunsaturated fatty acid (PUFA), sea urchin gonad could be used as a potential resource of such type ingredients. In the present study, lipid was extracted from sea urchin (Strongylocentrotus nudus) gonad, without using organic solvent but using an enzyme-assisted aqueous method and a supercritical carbon dioxide (SC-CO2) method. The yield of lipid extracted was calculated in comparison with the soxhlet extraction using ethyl ether as solvent. The results showed that enzyme-assisted aqueous extraction allowed recovering 82.0 ± 2.1, 76.0 ± 2.3, 72.9 ± 3.6, and 61.5 ± 1.6% of sea urchin gonad lipid from the sample hydrolyzed by papain, neutral protease, alkaline protease, and trypsin, respectively. Meanwhile, a lipid yield of 53.7 ± 2.6% was achieved by SC-CO2 extraction. The lipid obtained was divided into unsaponifiable (sterol) and fatty acid, and analyzed by GC–MS. Results demonstrated that the compositions of sterol and fatty acid were very similar for samples extracted by different methods. PUFA was the chief component which accounts for approximately 35% of the total fatty acid.