Decaf coffee is a popular choice for those seeking the coffee flavor without the jitters. Chemistry plays a significant role in the decaffeination process. Three common methods are used: carbon dioxide, Swiss water, and solvent-based. The Swiss water method is favored for its chemical-free approach and preserving the natural flavor of coffee. Solvent-based methods, while effective, use chemicals like ethyl acetate and methylene chloride. Safety concerns exist around the use of these chemicals, but the residual amount in coffee is minimal. Overall, decaffeination removes some flavor compounds, but methods like the Swiss water process aim to retain as much aroma and flavor as possible.
https://theconversation.com/retaining-flavor-while-removing-caffeine-a-chemist-explains-the-chemistry-behind-decaf-coffee-233196