Decaffeination - CO₂ Process

CO₂ Process

This process is technically known as supercritical fluid extraction. Pre-steamed beans are soaked in a bath of supercritical carbon dioxide at a pressure of 73 to 300 atmospheres. After a thorough soaking for around ten hours, the pressure is reduced, allowing the CO₂ to evaporate, or the pressurized CO₂ is run through either water or charcoal filters to remove the caffeine. The carbon dioxide is then used on another batch of beans. This liquid works better than water because it is kept in supercritical state near the transition from liquid to gas, combining favorable diffusivity properties of the gas with increased density of a liquid. This process has the advantage that it avoids the use of potentially harmful substances.