Selectivity of supercritical carbon dioxide in the fractionation of fish oil with a lower content of EPA + DHA

A sample of fish oil containing 4.6% and 6.7% of the fatty acids EPA and DHA, respectively, was extracted from freeze-dried slices of a speckled fish (Pseudoplatystoma corruscans). Solubility of the oil was measured in supercritical carbon dioxide (scCO2) at the temperature of 40 °C and pressures of 100, 200, 300 and 400 bar, and at temperatures of 50 and 60 °C and pressures of 200, 300 and 400 bar. The fatty acid compositions of some extracts were determined at the temperatures of 33, 40, 50 and 60 °C and within the same range of pressures. Values for solubility could be correlated by the Chrastil equation, which after fitting, was able to interpolate and extrapolate values for solubility which agreed in order of magnitude with experimental values reported in literature. The scCO2 was selective in fractionating the triacylglycerols containing the fatty acids EPA and DHA under the conditions of 100 and 200 bar, thus proving the technical viability of fractionating fish oils with lower contents of these fatty acids in the triacylglycerol molecules.