Question

How is caffeine-free coffee made? Does it come from a special type of coffee plan, or it done in the roasting process?

Answer

All coffee beans have caffeine, so right now there is not a naturally grown decaffeinated coffee bean. However, there are companies trying to genetically modify the coffee bean plants to achieve that. Maybe someday there will be a decaffeinated coffee bean and that will be a tremendous change.

At the present, coffee beans are decaffeinated when when the beans are green, before they are roasted. There are two ways of making decaf coffee. One is using a chemical solvent, and the other way is to use the Swiss Water process utilizing charcoal and water.

Your ears should perk up when you hear chemical solvent. The particular solvent used in that process is Methylene chloride or ethyl acetate. First the solvent is applied to to absorb the caffeine from the beans. Then the beans are washed to clean off the chemical.

The other decaffeination method is called the Swiss Water method. No chemicals are used. Instead, the green beans are soaked in hot water and then filtered to release caffeine, This method does not remove any coffee solids from the green beans, and the beans are 99.9% caffeine free and retain most of their flavor and smell. The process started in Switzerland in the 1930s, and today is only done at a Swiss Water decaffeination facility near Vancouver Canada.

With either process, some of the bean's subtle flavor is lost.

Source: Wikopedia: Decaffeination