Since I had till only recently avoided decaffeinated coffees altogether, I had likewise avoided the various and sundry methods that are used to decaffeinate coffee. Each has its benefits and drawbacks… and the story of which is a plus and which is a minus can vary quite a lot, depending on who’s telling the tale.
The “original” chemical process — KVW, or European processing — uses methylene chloride as its decaffeinating agent. Methylene chloride is a powerful solvent, and it’s been identified as a probable cancer causing agent. Its use is, consequently, strictly regulated by the FDA… and even more strictly regulated by the European Union, which oversees the process in Germany, where much of the world’s coffee is decaffeinated. KVW persists as a popular method because it results in arguably the best tasting coffee… because this solvent so aggressively leaches out caffeine it has little impact on the bean’s flavor.
A second chemical process is increasingly popular — Ethyl Acetate, or Natural processing — uses ethyl acetate in a process that’s virtually identical to the KVW method, except that the solvent is itself naturally derived [it can be found in an entirely organic state in some fruits, like apples. peaches and pears.]
Next are two methods — Swiss Water process, and CO2 — that each make a claim of being chemical free. These claims aren’t entirely accurate. Water is a chemical. CO2 is a chemical. They are, each in their own way, solvents. They are, however, far more common and inert chemicals than either of the ethyl-based solvents.
The Swiss Water process involves stewing the green coffee beans in very hot [nearly boiling] water, which extracts not only caffeine, but virtually every flavor agent in the bean. After this “flavor saturated water” is filtered to remove the caffeine, new coffee beans are added. The theory is that this next batch of coffee will lose only its caffeine, as the water is already saturated with coffee flavor compounds. My own experience suggests that at least some of the flavor-carrying coffee oils are forever lost in this process, and the coffee’s brightness is irrevocably muted.
The CO2 process would seem to offer tremendous potential for decaffeination. The CO2 process compresses carbon dioxide to a liquid state, which is circulated with wet, warmed green coffee beans. In its highly pressurized state, the CO2 acts as a particularly selective solvent, binding with the caffeine to carry it to another chamber. where the caffeine is removed, and the CO2 is recirculated. It’s an elegant method — though one that is perhaps not yet perfected… all CO2 processes are apparently not created equal, nor are their results.
On the whole, the same can be said of all decaffeinating processes.