(623n) Solubility of Vanillin and Vanillic Acid in Supercritical Carbon Dioxide

Vanilla (Vanilla planifolia Andrews) has been highly prized for its aroma, and it is now considered the most important flavoring in food and perfume industries. The development of vanilla aroma takes place during processing of green vanilla beans to produce cured vanilla beans, during which the green and odorless fruits become black and highly aromatic pods. Vanillin and vanillic acid are components of vanilla aroma which is obtained from a natural fermentation process.

Since most of the components that provide the flavor are volatile and thermo-labile, extraction and purification methods of vanilla extracts determine the overall quality of the final product. Actually, the main extraction method for vanilla oleoresin is multistage lixiviation, or leaching at 80°C employing ethyl alcohol, but if the process does not have a good control of temperature, degradation of vanilla may occur and a loss of quality extract exists.

Supercritical extraction with CO₂ seems to be a good alternative. Due to carbon dioxide’s relatively low critical temperature (Tc= 304.4 K), it is especially suitable for processing thermo-labile compounds. Information about solubility of solids in supercritical fluids is of great importance because supercritical fluids have several advantages over organic solvents about physical properties. Accurate experimental solubility data are fundamental to test theoretical, empirical or semi-empirical models. Semi-empirical models based on density are common approaches used to correlate experimental solid solubilities in supercritical fluids.

The aim of this work is to present new experimental solid solubilities of vanillin and vanillic acid in carbon dioxide, at 313, 323 and 333 K an pressures up to 30 MPa, based on the static-analytical method. The solubility data were correlated with the Mendez-Santiago and Teja model.

* Corresponding author: e-mail: lgalicial@ipn.mx (Luis A. Galicia-Luna)