There are nutritional and dietary factors, such as those linking excess blood cholesterol to heart diseases and cancer, that justify the development of a technology for the reduction of cholesterol levels in consumed meals. Previous studies have demonstrated the viability of using CO2 for the removal of cholesterol from butter oil. Cholesterol has higher solubility in ethane than in CO2. The use of CO2/ethane mixtures, therefore, presents as an attractive alternative, as a compromise between the higher ethane cost better cholesterol removal efficiency obtained and envolved. Using a high pressure experimental extraction apparatus that allows the independent control of temperature and pressure, cholesterol solubilities in supercritical CO2/ethane mixtures with 8%, 16%, 34%, 76%, 88% e 96,5% of ethane were determined at 328,1 K and pressures from 120 to 190 bar. Experimental results show an increase in solubility with pressure and a composition of ethane in the mixture. Experimental data were correlated with a thermodynamics model that uses Peng-Robinson equation with two different mixing rules: the normally used van der Waals and a rule that considers the interaction parameter density dependent resulting in a quartic equation of state. The density dependent mixing rule reveal more successful in the correlation of experimental data.
Supercritical extraction; cholesterol; supercritical ethane; thermodynamics model
