Caffeine may be the most widely used legal drug in the world. The chemical occurs naturally in coffee beans, tea leaves, cola nuts and mate leaves. Most people consume caffeine in coffee, tea, soda or over-the-counter medication. First isolated from coffee in 1820, caffeine is a stimulant, a diuretic and lethal in doses of 10 g or more. The average cup of coffee contains about 150 mg of caffeine, while espresso may have triple that amount. Extracting caffeine from coffee requires specialized chemicals and equipment. You may not want to try this in your kitchen.
The Direct Method
Step 1
Steam green, unroasted beans to soften them. Instead of steaming, soak the unroasted beans in hot water.
Step 2
Apply a solvent to the beans that binds with caffeine. The Coffee Science Information Centre states that the two most commonly used solvents are methylene chloride and ethyl acetate. Ethyl acetate is a chemical that naturally occurs in many fruits, so coffee that uses ethyl acetate may be labeled "naturally decaffeinated."
Step 3
Rinse the beans well to remove the caffeine and any traces of solvent. Manufacturers use methylene chloride in the production of paint stripper, metal cleansers and de-greasers. The Food and Drug Administration requires that coffee decaffeinated using methylene chloride have less than .1 part per million of methylene chloride residue.
Water Extraction
Step 1
Soak unroasted, green coffee beans in hot water to dissolve all soluble compounds -- including caffeine. Discard the beans after soaking.
Step 2
Remove only the caffeine from the solution using a specialized carbon filter, leaving all other compounds intact. Keep the solution at the same temperature throughout the process.
Step 3
Introduce a new batch of raw coffee beans into the solution. Because the solution is already saturated with all the soluble compounds except caffeine -- which was filtered out -- only the caffeine will be removed from the new batch of coffee beans, according to Frostburg University's General Chemistry Online.
Step 4
Remove the now decaffeinated beans and re-filter the solution. You may reuse the solution indefinitely if you remove the caffeine after each use.
Tips and Warnings
- Although decaffeinated beans will always taste slightly different, starting with high quality beans will help ensure a high quality decaffeinated coffee.
- Do not attempt to decaffeinate coffee at home.
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