Decaf coffee is made by removing about 97% or more of the caffeine naturally found in green, unroasted coffee beans. The process generally involves soaking or steaming the beans to open their pores and make the caffeine more accessible, then using one of several methods to extract the caffeine. Common decaffeination methods include:
- Solvent-based methods (direct and indirect): The beans are steamed, then rinsed with a liquid solvent such as methylene chloride or ethyl acetate that selectively bonds to and removes caffeine. The solvent is then evaporated and the beans steamed again to remove any residue. In the indirect method, beans are soaked in water, then the water is treated with solvent to remove caffeine before being reabsorbed by the beans to retain flavor.
- Swiss Water Process: Beans are soaked in hot water to dissolve caffeine and flavor compounds. After removing caffeine from the water through carbon filtration, the caffeine-free flavor-rich water is reused to decaffeinate new batches of beans without chemical solvents.
- Supercritical Carbon Dioxide Process: Beans are soaked in water, then exposed to CO2 under high pressure and temperature. The supercritical CO2 acts like a gas to penetrate the bean but dissolves caffeine like a liquid, selectively removing caffeine while preserving most flavors.
After decaffeination, the beans are dried and roasted like regular coffee beans. This results in coffee that tastes similar to regular coffee but contains only about 2 mg of caffeine per cup compared to 70-140 mg in regular coffee.
