Supercritical Carbon DioxideIn this direct contact method, green beans are first softened by steam, to bring caffeine to the beans' surface. Next, they are immersed in carbon dioxide at a high temperature and pressure - in this "supercritical" state the carbon dioxide behaves as if it were a liquid while remaining a gas. It penetrates the beans to extract the caffeine.The supercritical carbon dioxide is then drawn off, leaving the beans 97 percent free of caffeine. The solvent residue remaining on the beans dissipates as a gas when the beans return to room temperature. Here are a few facts on Coffee Decaffeination. |