Thermodynamics Research Center / ThermoML | Journal of Chemical Thermodynamics

ABSTRACT

This manuscript presents new phase equilibrium data for capsanthin in pure and trioleinentrained SuperCritical (SC) carbon dioxide (CO2). The aim of the work was to determine the cosolvent effect of triolein on capsanthin by comparing solubility results in a ternary (CO2 + triolein + capsanthin) system and binary (CO2 + capsanthin) system at 313 or 333 K and 19 to 34 MPa. For this, authors isolated capsanthin from red pepper (Capsicum annuum L.) and tested it using a dynamicanalytical method in an apparatus with recirculation and online analysis of the CO2-rich phase. Within the experimental region, the solubility of capsanthin in pure SC-CO2 increased with system temperature and pressure with a positive interaction between the two factors. Solubilities ranged from a minimal of 0.65 microM at 313 K and 19 MPa to a maximal of 1.97 microM at 333 K and 32 MPa. The concentration of triolein in the ternary system was equivalent to that its solubility in pure SC-CO2 depending on system temperature and pressure conditions. Because of a crossover experimentally observed at approximately 29.6 MPa, the solubility of triolein ranged from a minimal of 0.16 mmol/mol at 19 MPa to a maximal of 0.41 mmol/mol at 33 MPa, both at 333 K. Independent of system temperature and pressure, capsanthin solubility in triolein-entrained SC-CO2 increased by a factor of about 3 (triolein-induced enhancement factor) as compared to its solubility in pure CO2, under similar conditions of pressure and temperature. The maximal solubility of capsanthin in SC-CO2 experimentally observed in this study was 5.27 mM at 333 K and 33 MPa in the presence of 4.10 mM triolein.