The process of decaffeinating coffee typically involves the use of chemical reactions to remove or reduce the caffeine content. There are different methods used in the industry, but two common techniques are the solvent-based method and the Swiss water process.
Solvent-based method: In this process, a solvent, often either methylene chloride or ethyl acetate, is used to extract caffeine from the coffee beans. The solvent is applied to the beans, and it selectively bonds with the caffeine molecules. This step involves a chemical reaction where the solvent interacts with the caffeine to form soluble complexes. The solvent is then separated from the beans, taking the caffeine with it. The beans are then steamed or rinsed to remove any remaining solvent, resulting in decaffeinated coffee.
Swiss water process: This method utilizes water as the solvent to extract caffeine from the coffee beans. Initially, a batch of green (unroasted) coffee beans is soaked in hot water, which dissolves the caffeine and various other compounds from the beans. This water, referred to as "flavor-charged" water, is then passed through activated charcoal filters to remove the caffeine while retaining the coffee's flavor compounds. This filtration process involves adsorption, where the caffeine molecules are attracted and bound to the activated charcoal, leaving behind the flavor compounds. The resulting caffeine-free water, known as "flavor-charged" water, is recycled and used for the next batch of beans. The beans, now free of caffeine, are dried and roasted to produce decaffeinated coffee.
In both processes, chemical reactions are involved to selectively remove or reduce the caffeine content from the coffee beans, resulting in decaffeinated coffee while retaining most of the flavor compounds.