How Coffee is Decaffeinated
Coffee is decaffeinated in its green state before the coffee is roasted. This process is usually arranged by the importer and done at a third-party facility outside the coffee’s country of origin. While there are many facilities that will decaffeinate coffee, there are really only a few main methods to remove the caffeine (there are subtle variations within each method to allow decaffeinating companies to hold patents on their process).
The solvent process ihtois the most common method of caffeine extraction due to availability of facilities that use this method and the relative affordability of the process. Methylene chloride and ethyl acetate are the two solvents that are mostly used. Typically if the method of decaffeination is not stated on the coffee you buy, you can bet methylene chloride was used due to its lower cost. Ethyl acetate can be derived from fruit or sugar, so the coffee can then be labeled “naturally decaffeinated.”Regardless of which solvent you use, the process is about the same. The lot of beans are soaked in warm water to help increase the surface area of the beans and allow the solvent to penetrate the bean. The solvents then bond with the caffeine within the bean allowing the processor to then remove the solvent/caffeine solution while leaving behind the flavor elements inside the bean. The solution can then be further processed to separate the solvent from the caffeine and resell it to places like soda and energy drink companies (which is why this process is more affordable to use). To remove any remaining solvents within the bean, the processors heat the beans to the boiling point of the solvents (100F-175F) which evaporates any remaining residues.
What you end up with is a decaffeinated green coffee that is about 99% caffeine free with a solvent residue of about 1 part per million (the FDA limit is 10 parts per million). If that freaks you out, know that the burning point for solvents is less than 175F and coffee is roasted to above 400F, which should burn off any remaining residues. But if you're still not 100% comfortable with that process, there are other options.
The water process (AKA Mountain Water Process and Swiss Water process, both decaffeinating brands) uses warm water and charcoal filters to remove the caffeine from the beans. Because no chemicals or solvents are used in the process, it allows beans to remain labeled “organic” if they were organic to begin with. This is also a more expensive method because, unlike the solvent process, the caffeine can’t be removed from the charcoal filters and resold to other industries.
The first step in the water process is to warm the beans to a temperature in which the soluble components of the bean are released into the water but the flavor elements of the beans remains. This water is then separated from the beans and run through a charcoal filter until almost all (99%) of the caffeine is removed. When the desired caffeine level is achieved, the water and remaining soluble components are reunited and reabsorbed by the green beans. The result is a caffeine free green coffee with no residual solvents or chemicals.
The last decaffeination method is the carbon dioxide method, which is also a chemical free method but very expensive due to the large investment the processor must make on equipment in order to work with a liquid state CO2. This is the least popular method of decaffeination, mainly due to price.
As with the other processes the first step is to soak the beans in warm water to open them up and allow the liquid carbon dioxide to penetrate the bean. Caffeine in the beans bonds with the liquid CO2 and leaves behind the flavor compounds. The CO2 can now be removed and the caffeine can be separated from the solution and sold to other industries.
Finally, the beans are dried and you end up with a chemical free green coffee.