Decaf coffee is made by taking the caffeine out of the beans. Bam, boom, done! I did it!
But seriously, how do they take the caffeine out of the beans?
History of the decaffeination process
The first process of decaffeination is credited to German coffee merchant Ludwig Roselius. Ludwig was the founder of the coffee company Kaffee HAG that sold decaffeinated coffee to consumers who were intolerable to caffeine (Senats Press, 2003).
The earliest method of extracting caffeine from green coffee involved steaming the green coffee beans to loosen the molecular structure, then treating the beans with gaseous chemicals to release the caffeine from salts, then using benzene as a solvent to extract the caffeine out of the beans, and lastly, using dry steam on the beans to conclude the overall process (U.S. Patent No. 897,763, 1906). Later on, benzene was found to be carcinogenic and was later substituted for organic solvents like dichloromethane and ethyl acetate which make up around 98% of all solvents used in solvent-based decaffeination processes (Clarke, 2001, p. 108-109).
Other Decaffeination Processes
The indirect method involves a lot more steps of extracting caffeine, as well as extracting the flavors, out of green coffee beans. Green coffee beans are placed in hot water until the caffeine and flavors are pulled out of the beans. The beans are removed, and you’re left with coffee extract. A solvent is added to the coffee extract where the caffeine will then bond to it. The coffee extract is heated up to allow the caffeine solvent to evaporate. Then you’re left with a decaffeinated coffee extract and no solvent. The green coffee beans are then placed back into the extract where your result is decaffeinated green coffee beans (U.S. Patent No. 4,409,253, 1981). The entire process is much more complicated than that but that’s one way of explaining it simply. Here’s an illustration of the entire decaffeination process.
Swiss Water Process
The Swiss Water Process is a registered decaffeination process under Swiss Water Decaffeinated Coffee Inc. Their decaffeination process only involves water, carbon, and roughly 10 hours of processing. To summarize their ‘bean-side’ decaffeination process, green coffee beans are soaked in water to dilate, and then the water is drained. Next, Green Coffee Extract (GCE) is added to the dilated green coffee beans where the GCE extracts the caffeine from the beans while simultaneously soaking the beans with coffee flavors. The green coffee beans are dried and then ready to be bagged for roasting (SWC, 2019). Check out their video that goes through the entire decaffeination process including how the GCE is produced:
Supercritical CO2 Process
Super…what? This decaffeination process is really cool. Take CO2, heat it above 308K, pressurize it above 75.062 bar, and then you have supercritical CO2 that can be used to extract caffeine from green coffee beans (Haghbakhsh, 2013).
I could explain, in detail, how the supercritical CO2 process works, but the University of York has this nice diagram explaining the entire process.
The supercritical CO2 process is very effective at only extracting the caffeine out of the green coffee beans and keeping the flavors of the beans intact, but there are some drawbacks to this intricate decaffeination process. While the supercritical CO2 process is efficient at caffeine extractions, the processing parameters need to be carefully specified. Supercritical CO2 exists under extreme conditions that have to be controlled and the process of pumping this CO2 into the extraction vessel as well as constantly changing the vessel pressure as you move the CO2 in and out. Because of all of these intricacies, this decaffeination process is very expensive and is reserved mainly for coffee plants that produce massive amounts of decaffeinated coffee (University of York).
Decaffito & Naturally Caffeine-free Coffee
There’s a new term floating around called ‘Decaffito’ which is any Coffea Arabica variety that’s naturally low in caffeine or almost devoid of caffeine in the beans (DS. Akaffou, 2009). Along with Arabica varieties being discovered with lower levels of caffeine, there’s also another coffee species that is already naturally devoid of caffeine, Coffea Charrieriana. You can read more about Coffea Charrieriana here.
The discovery of low caffeine Arabica varieties and the utility of Coffea Charrieriana is still new but this opens another door for experimentation of creating coffee hybrids that have low or possibly zero caffeine without having green coffee beans to go through a decaffeination process.
Before writing this blog post, I thought that the decaffeination process was a little more straightforward and that there was only one method of doing it, the Swiss Water Method since that’s how the decaf coffee I buy is processed. To think that there are several ways of pulling caffeine out of green coffee beans and the science behind it is complex yet crazy cool! I hope that you learned something new about decaf coffee, I know I sure did.