Supercritical carbon dioxide extraction of caffeine from guaraná

Abstract A single-pass system was designed to study extraction of caffeine from wet guarana seeds using supercritical carbon dioxide. Extraction was studied as a function of pressure and temperature to determine caffeine solubility at equilibrium conditions between 136.1 and 272.2 atm and temperatures of 35, 45, and 55 °C. Solubility of caffeine into supercritical CO 2 was affected directly by CO 2 density. Caffeine solubility was modeled by using thermodynamic relationships and the Peng-Robinson equation of state on a water-free basis. Effective diffusion coefficients of caffeine in ground guarana seeds were determined by conducting long-term extraction experiments.