Supercritical carbon dioxide fractionation of lipids: Solubility behavior to process development

A systematic study on the solubility behavior of lipid components in SCCO2 was carried out from binary to ternary and higher systems. The solubility trends of lipid components as affected by operating conditions and solute properties, the nature and extent of the deviation from binary behavior observed in multicomponent systems and the predictive ability of the binary data were determined. Also, the implications of the findings for fractionation processes were evaluated. Available literature binary solubility data of major (fatty acids, mono-, di- and triglycerides and fatty acid esters) and minor lipid components (stigmasterol, alpha-tocopherol, beta-carotene and squalene) were correlated using Chrastil's equation and estimated model parameters were used to determine the solubility trends. The study of solubility behavior was hampered by the wide discrepancies between the experimental data and lack of phase behavior information, which is required for accurate interpretation of the solubility behavior such as melting behavior. The physical state of a solute was observed to have a significant impact on the solubility behavior; however, information on the melting behavior in SCCO2 is far from complete and requires further research. Although binary solubility data provide valuable information on the relative solubility of lipid components and can be used to assess the potential of a fractionation process, its predictive ability is limited as the presence of other solutes affects the solubility behavior and thus the selectivity in multicomponent systems. General solubility trends can be established for ternary and higher systems by investigating the extent and nature of the deviation from binary behavior; however, further research is required to confirm the observed trends and determine the practical implications.; A fractionation column was designed and built to study the SCCO 2 column fractionation of fats and oils. Semi-continuous fractionation of canola oil deodorizer distillate was carried out to determine the feasibility of value-added processing of this feed material for the recovery of bioactive components such as sterols and tocopherols and to determine the effect of operating conditions (temperature, temperature gradient and pressure) on the yield and selectivity of the fractionation process. Sterol concentration as high as 40% (GC Area %) was achieved in the residue using a fractionation pressure of 25 MPa and a linear temperature gradient of 70--100°C along the column. The findings indicate the potential of canola oil deodorizer distillate as a source of sterols and warrant further research on the countercurrent column fractionation to improve the separation efficiency.