Were often asked about how coffee is decaffeinated or does it just grow that way on trees. Coffee plants (for now, never give up on science) only produce caffeinated beans so it must go through a process to remove the caffeine. Here in the states any beverage producer can claim “caffeine free” if its 97% caffeine free and in some countries it has to be 99% caffeine free. Since coffee contains caffeine naturally it has to be removed but will still contain “trace” amounts or a very small percentage (2-13 Milligrams of caffeine) when finished. There are a methods used to arrive at the point of “decaffeinated coffee” and no we’re not going to discuss them because decaf coffee is for quitters. Just kidding.
The main decaffeination processes are Swiss water, Natural, Direct and Co2.
Swiss water method
This is a process where a green coffee extract (GCE) is used instead of any chemicals. The beans are first cleaned with water and then a green coffee extract is introduced to start the extraction process. To get a little nerdy on ya, that means that the caffeine will move from a higher concentration (bean) to a place of lower concentration (extract). Since this extract contains essential oils and other components of the green bean mostly caffeine finds its way out to the extract leaving behind the good flavor components of the bean. These beans then go through a carbon filtering system which traps the caffeine until it’s at 99.9% caffeine free. If a 12oz cup contains 120-180 mg of caffeine then a Swiss water decaf cup of the same size would be between 2-6 mg.
The Direct method
This method will use solvents such as methylene chloride. Basically the green beans are moistened and then immersed in the solvent. The solvent does its job by extracting the caffeine and then the beans are rinsed thoroughly. Usually the beans are re-soaked in the decaffeinated water to reabsorb flavor compounds lost during initial extraction. Then a good steam bath for the beans will help to eliminate, or shall I say evaporate any remaining solvent residue. If any solvent residue is left on the bean it gets removed during the roasting process.
Methylene chloride process is thought by some in the coffee industry to maintain coffee flavor better than other processes.
This method uses Ethyl acetate and is naturally found in fruits (why it’s called natural). The beans are first steamed or soaked in water to enable easier and faster extraction of the caffeine. The caffeine is then drawn out of the coffee beans by a combination of ethyl acetate and water. In both methods the beans are re-soaked in the decaffeinated water to reabsorb any flavor compounds that “leaked” out. Finally the beans are steamed to remove any residue and gently dried to prepare for roasting.
Carbon Dioxide method
In this method the beans are soaked in compressed Carbon Dioxide which extracts the caffeine. Highly compressed carbon Dioxide at this level will look like liquid with a viscosity of gas which is very effective in extraction. As the beans are introduced to the solvent the caffeine migrates out into the solvent. The beans then get a good rinse afterwards and are ready to be roasted.
Hopefully this article leaves you delightfully enlightened and empowered to make better decisions regarding decafs.