Decaf! It’s bad, right?
Not anymore, or at least, not necessarily.
Decaffination started as a concept for coffee in 1903, when German merchant Ludwig Roselius received a shipment of green coffee beans that had at some point in their sea journey been soaked in sea water. He found that after roasting, the coffee (despite being notably salty), still tasted of coffee, but that the seawater had removed much of the soluble caffeine from the beans. By 1906, Roselius and his colleagues had refined the process to one of steaming the beans to open them up and then using a solution of benzene to bind to and remove the caffeine. Over the next century and a bit, we have come a significant way from benzene, which was later discovered to be rather carcinogenic. Modern decaffeination does follow similar ideas of isolating and the drawing caffeine out from the coffee beans, using various methods to specifically bind to the caffeine.
The three main forms of decaffeination on the market today are referred to as the Swiss Water Process, Supercritial Carbon Dioxide Method, and the Direct Solvent Process.
The Direct Solvent Method sounds pretty unappealing from a marketing standpoint and is often referred to as the Sugarcane Process. This is because one of the common solvents, Ethyl Acetate, is a naturally occurring chemical produced from Sugarcane or various fruits. To use the Ethyl Acetate to remove caffeine from the coffee, the green coffee beans are first steamed or soaked to soften and open up the very hard, dense beans. The beans will then be soaked in a solution of Ethyl acetate. The Ethyl Acetate binds directly to the caffeine, drawing it out of the beans. This solution will be refreshed several times during the process as the Ethyl Acetate in the solution becomes saturated with Caffeine. Once all the caffeine has been removed front he beans, they will be rinsed and then steamed a final time to remove all traces of Ethyl acetate from the beans. The beans are then dried and polished, before being shipped to roasters. Methylene chloride can be used in place of the Ethyl acetate in this process, but this is not a naturally derived compound and would be referred to as Chemically Decaffeinated, or a similar label instead of as Sugarcane Processed.
The Swiss Water Process is a far more common process to see in specialty coffee roasting as a chosen decaffeination method, due to it not requiring any chemical addition to decaffeinate the beans. In the Swiss Water Process, (so called because it is a patented process only used by companies related to the patent) the first step is to create a GCE or Green Coffee Extract. This is done by steeping large amounts of Green Coffee Beans to leech out all soluble material from the beans. These beans are now no longer useful and will be discarded, but the GCE only needs to be made once and can then be used again and again. Specialized Carbon rods are used to capture the caffeine from the green coffee extract, leaving all the other available coffee solubles minus the caffeine suspended in the solution. A new batch of steamed green coffee will be added to this bath. If you remember how osmosis works from Biology class in school, it may be apparent that the next thing to happen will be caffeine leeching out of the fresh green coffee and into the green coffee extract. This process takes place because all the other solubles from the coffee are even between the green beans and the GCE in which they are steeping. The GCE will be swapped out, decaffeinated, and run back through the beans several times until the caffeine is all, or mostly all, removed from the coffee beans, which are then able to be dried, rested, and packed for transport to roasters.
The final process, the Supercritial Carbon Dioxide Method, is in my opinion by far the most interesting. It is also much less common to see, as it requires expensive, specialized equipment. Carbon Dioxide is a chemical that requires extremely specific conditions to be held in its “supercritical form”, where it will behave like a gas but with the density of a liquid. When left to open air, Carbon Dioxide (CO2) is present either in its solid or gaseous form, as seen in the sublimation of dry ice into CO2 gas. If you hold the CO2 above its critical temperature and critical pressure, the dense, gaseous CO2 has remarkable properties for selectively binding to caffeine from green beans, which are “soaked” in the liquid-like gas. The beans can then be removed from the solution, leaving decaffeinated beans behind. Though this form of decaffeination has very minimal effect on the raw green beans and is quite ecofriendly as it relies purely on naturally occurring CO2, it’s still a rather expensive form of decaffeination due to the specialized equipment required.
Any of the above forms will leave a decaffeinated raw bean, which then is distributed to various roasteries before making it to your cup. Any of the listed methods can produce a wonderful cup, though it's noted that the in between step of roasting can be where quite a bit of challenge can be caused. Because of the various methods used to open the pores of the beans to strip the caffeine, decaffeinated green beans react significantly differently than whole, full caffeine green beans during the roasting process.
It is also of note that, once again as the beans have decreased in density during the decaffeination process, they stale significantly faster than caffeinated beans, in a matter of weeks. For best outcome with decaf, it’s my personal recommendation to find and focus on a roaster who seems to have their hands on the different roasting required to really make these beans shine, and to freeze the beans in an airtight container should you expect to have them around for more than a week or two.
Looking for a good decaf to start out with? For espresso, I’m quite a fan of Rebel Bean’s Big Chill Decaf. For a lighter roast or pourover, why not try the Organic Peruvian Decaf Coffee by Whisky Hill?
Have questions or comments about this post? Let us know!
Whisky Hill Organic Peruvian Decaf Coffee Beans — Coffee Addicts
Rebel Bean Coffee Big Chill Espresso Decaf Coffee Beans — Coffee Addicts
Image taken from A Complete Guide To Decaf Coffee – Coffee Hero
