Phase equilibria of fish oil in sub- and supercritical carbon dioxide

Abstract

Measurements of phase equilibria of fish oil from the sand eel ( Ammodytes lancea) in sub- and supercritical carbon dioxide were performed at pressures from 6 to 65 MPa and temperatures at 293.2, 313.2, 353.2 and 393.2 K. At none of the temperatures, carbon dioxide and fish oil were completely miscible. Phase inversion was observed at 293.2 K and 25.2 MPa, and at 313.2 K and 42.0 MPa. We identified 33 components in the fish oil including free fatty acids, cholesterol, wax esters, di- and triacylglyceroles by supercritical fluid chromatography on a nonpolar capillary column. Vitamin E and squalene are present in trace amounts. Components containing fatty acids were identified by the carbon number and no attempt was made to distinguish between fatty acids with different degrees of unsaturation or positions of the double bonds. The experimental temperatures, pressures, mass fractions, and calculated equilibrium ratios are reported in tables, and examples are shown in graphs. The mass fractions and the equilibrium ratios are reported on a carbondioxide-free (CO 2-free) basis.