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

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 +/- A 2.1, 76.0 +/- A 2.3, 72.9 +/- A 3.6, and 61.5 +/- A 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 +/- A 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.