by Matt Gibson
There are four major decaffeination methods that are used to make decaf coffee today. These methods are known as the Direct Solvent Process, the Indirect Solvent Process, the Swiss Water Process, and the Carbon Dioxide Process.
Each of these decaffeination methods begin in a similar fashion, by using green coffee beans, and extracting the caffeine before the drying and roasting process begins. As caffeine is a water soluble compound, it makes sense that the first step in the extraction process is to soak the green coffee beans in order to leach out the caffeine.
The problem which then arises for coffee makers, is that caffeine is not the only water soluble compound in coffee. In fact, there are over 1,000 water soluble compounds in coffee beans, many of which are responsible for its robust, and complex flavors, as you know from brewing the roasted grounds.
Water is not a selective solvent, as it will remove more than just the caffeine from the green coffee beans. Therefore, each of the caffeine removal processes use a selective solvent to draw out the caffeine without removing too many of the other important compounds so as to limit alterations and avoid diminishing the flavor and quality of the beans in the process.