Solubility of caffeine from green tea in supercritical CO sub(2): a theoretical and empirical approach

• Published in: Journal of food science and technology 2015-12, Vol.52 (12), p.8004-8013
• Main Authors: Gadkari, Pravin Vasantrao, Balaraman, Manohar
• Format: Article
• Language: English
• ISSN: 0022-1155; 0975-8402
• DOI: 10.1007/s13197-015-1946-5

Decaffeination of fresh green tea was carried out with supercritical CO sub(2) in the presence of ethanol as co-solvent. The solubility of caffeine in supercritical CO sub(2) varied from 44.19 10 super(-6) to 149.55 10 super(-6) (mole fraction) over a pressure and temperature range of 15 to 35 MPa and 313 to 333 K, respectively. The maximum solubility of caffeine was obtained at 25 MPa and 323 K. Experimental solubility data were correlated with the theoretical equation of state models Peng-Robinson (PR), Soave Redlich-Kwong (SRK), and Redlich-Kwong (RK). The RK model had regressed experimental data with 15.52 % average absolute relative deviation (AARD). In contrast, Gordillo empirical model regressed the best to experimental data with only 0.96 % AARD. Under supercritical conditions, solubility of caffeine in tea matrix was lower than the solubility of pure caffeine. Further, solubility of caffeine in supercritical CO sub(2) was compared with solubility of pure caffeine in conventional solvents and a maximum solubility 90 10 super(-3) mol fraction was obtained with chloroform.