Preliminary study of caffeine extraction from Ilex guayusa L. leaves using supercritical carbon dioxide.

Caffeine (1,3,7 - trimethylxanthine) is a natural molecule present in a variety of plants, seeds or fruits standing out in coffee, tea, mate, cola nuts, cocoa and guarana. It is widely used in different industries, acting as a stimulant for respiratory and central nervous systems. Ilex guayusa L., is located in the Amazon region of Colombia, Ecuador and Peru. Plant leaves present alkaloids such as caffeine and theobromine. In this work, extraction of caffeine from Ilex guayusa L. leaves using supercritical carbon dioxide (SCCO₂) was studied. The overall caffeine recovery from plant matrix was determined as a function of time (0.17, 0.5, 1, 2 and 4 h) at the same extraction conditions (23 MPa and 328 K). Ethanol as cosolvent was introduced in the extraction vessel to soak the vegetable material before SCCO₂ was pumped. Cosolvent to solvent ratio remained constant in each experiment (3.5 g of ethanol / 100 g of SCCO₂). The highest caffeine recovery 89.7% was obtained after four hours of dynamic extraction. Barton´s model was used to analyze the extraction kinetics, data was successfully fitted (R2=0.974) and diffusion coefficient was determined using model assumptions. Information here is presented for the very first time, is useful to predict extraction yields and to promote further research with this natural material.