EXTRACTION OF LIPID FROM ABALONE (HALIOTIS DISCUS HANNAI INO) GONAD BY SUPERCRITICAL CARBON DIOXIDE AND ENZYME-ASSISTED ORGANIC SOLVENT METHODS

Abstract

ABSTRACT The objective of this study was to establish methods to extract lipids from abalone (Haliotis discus hannai Ino) gonad. Results showed that enzyme-assisted organic solvent extraction allowed recovering 60.00 ± 2.16% of abalone gonad lipid from the samples digested with neutral protease. In addition, a lipid yield of 82.56 ± 2.77% was achieved by supercritical carbon dioxide (SC-CO2) extraction. Thin-layer chromatography-flame ionization detection analysis indicated that lipid extracted by soxhlet method from H. discus hannai Ino gonad contained 89.05 ± 0.97% of triglycerides, 7.34 ± 0.80% of phospholipids, 1.46 ± 0.08% of cholesterol and 2.15 ± 0.09% of free fatty acids. The lipid extracted was divided into the unsaponifiable fraction (sterol) and the saponifiable fraction, and analyzed by gas chromatography mass spectrometry. Results demonstrated that the compositions of sterol and fatty acid were different for samples extracted by different methods, indicating that the extraction method could influence the composition of the lipids. PRACTICAL APPLICATIONS Shellfish by-products, such as viscera, contain high levels of nutrient material, such as protein, fat and polysaccharides, and have certain utility value. So far, there is a lack of utilization methods for the recovery of those substances. In our lab, an enzymatic hydrolysis process has been established to recover polysaccharides and protein (peptide) simultaneously from shellfish by-product (viscera). However, the enzymatic hydrolysis process did not involve the recovery of another important nutrient content, lipid. In the present study, the lipid was extracted from H. discus hannai Ino gonad by enzyme-assisted organic solvent method and SC-CO2 method. The two methods could be combined into the established enzymatic hydrolysis process to accomplish the comprehensive utilization of shellfish viscera.