Characterization of Cocoa butter saturated with supercritical CO2: Experimental set-up and Modelling

The main objective of this work was to study and to characterize cocoa butter and the binary system cocoa butter/supercritical carbon dioxide (SC-CO2). In this way, it was measured the density and the solubility of the heavy phase in equilibrium at high pressures at 40 and 50oC, as the density and compressibility of cocoa butter. The density measurements were done trough an autoclave with a sapphire window that can be under high pressures and an apparatus to measure the density, which bases in oscillating U-tube principle he solubility was measured using a synthetic method, through a cell with variable volume. At last, the compressibility measurements were done using a porosimeter of mercury. The obtained results were modelled in function of pressure. For the density and compressibility of the binary system (cocoa butter/SC-CO2) and of cocoa butter it was used the Tait Equation and the Modified Tait Equation. The solubility was modelled by the Peng-Robinson Equation of State with two mixing rules: Van der Waals (vdW) and Panagiotopoulos-Reid (P&R). For the solubility calculations of the cocoa butter modelcompound was considered the triglyceride 1-palmitoyl-2-oleoyl-3stearoyglycerol (POS) since it is the major triglyceride of cocoa butter. The thermo physical properties of the cocoa butter were predicted by four estimation methods: Ambrose, Joback, Constatinou-Gani and Fedors.