Solubility of a Multicomponent Glyceride Mixture in SC-CO2: Experimental Determination and Correlation

Lipid compounds are gaining increasing attention due to a wide range of applications in the food industry. Particularly, supercritical carbon dioxide (SCCO2) is being successfully employed as a green solvent in the extraction and fractionation of nonpolar lipids. Knowledge of the solubility of pure lipid-type substances and their mixtures in SCCO2 is essential for evaluating the viability of supercritical separation processes and for their subsequent design. Hence, both solubility measurements and thermodynamic modeling are of interest to researchers and process engineers and are receiving considerable attention in the literature. Solubility data of pure mono-, dior triglycerides in SCCO2 are to a certain extent reported in the literature. However, the information regarding solubility of complex multicomponent glyceride mixtures is relatively scarce. In this work, we report the solubility of a commercial glyceride mixture (51.9 % wt monoglycerides, 34.0 % wt diglycerides and 14.1 % wt triglycerides) in SC-CO2, measured in a variable-volume equilibrium cell at T = (313 and 323) K and pressures in the range of (10-35) MPa. Additionally, we apply two different equation of state based models, to represent the solubility data reported. The thermodynamic modeling is based on an appropriate selection of model substances to represent the glyceride mixture composition, which was determined by HPLCELSD and GC analysis, and an accurate estimation of the pure compounds properties required for the modeling.