High-pressure phase equilibrium data of carbon dioxide/food-relevant systems (2011-2022): Experimental methods, multiphase behavior, thermodynamic modeling, and applications

Abstract

High-pressure phase equilibrium data involving food-type substances and pure or cosolvent-modified pressurized carbon dioxide (CO2) published in the last decade are reviewed. Experimental data regarding binary, ternary, and multicomponent systems studied at 293–373 K and pressures up to 55 MPa are compiled. CO2/lipid-like substances (fatty acids, esters, triacylglycerols), essential oils, and their components are the most studied food systems, followed by systems containing biopolymers. The Vapor-Liquid Equilibrium is the most observed fluid-fluid transition at experimental conditions. The cosolvent effect of organic solvents in removing immiscibility gaps like the Vapor-Liquid-Liquid and the Liquid-Liquid boundaries, the antisolvent role of CO2 to some solutes, and its plasticizing effect on polymers and solid lipids are also highlighted in the context of solid-fluid equilibrium. The Peng and Robinson Equation of State coupled with the Van der Waals type mixing rules is still the main thermodynamic model applied for modeling phase equilibrium of these systems, despite some correlative limitations regarding multicomponent mixtures containing polar molecules. Combining classical Equations of State with the associative term and predictive models as Group Contribution methods is a reliable tool to improve the modeling of systems with complex phase behaviors. Fluid phase immiscibility regions and experimental conditions that favor the presence of a solid phase are mainly useful to set the appropriate operating point based on phase diagrams and the observed equilibria. For many applications, phase equilibrium is relevant in processing food-type substances destined for food or food-related applications and human consumption by processes employing CO2 as an extraction solvent, a fractionating, dispersant, precipitative, or atomizing (antisolvent) agent, or as a reaction medium for biocatalysis.