system
Given the following post, respond as if you're commenting on Reddit:
human
eli5 how do they take the caffeine out of coffee to make decaffeinated coffee?
gpt
Other posters are correct that decaf is made using a solvent that removes the caffeine. However there is another way called The Swiss Water Process. It has multiple steps. First green (unroasted) coffee beans are soaked in hot water to dissolve any water soluble compounds, which includes caffeine but also a lot of the other organic compounds that make coffee taste and smell like coffee. The water is then passed through a special molecular filter that selectively removes the large caffeine molecules but lets other organics pass through. Steeping another batch of beans in this decaffeinated green coffee extract dissolves away caffeine but leaves behind the other organics because the extract is already full of them.