Methods of Decaffeinating Coffee

Posted on: April 26th, 2013 by Andre Desomier 2 Comments


There are several different methods used in the coffee industry to decaffeinate coffee.

Organic/Natural Method
All decaffeinating methods take advantage of carbon dioxide (CO2), since when compressed, behaves partly like a gas and partly like a liquid, and has the property of combining selectively with caffeine. In most widely used CO2 processes the steamed beans are bathed in compressed carbon dioxide and the caffeine is removed from the carbon dioxide through charcoal filtering, commonly used in water-only process. However, with the organic/natural method the flavor components remain in the bean throughout the process, rather than being soaked out and then put back in again, as is achieved in both the Swiss Water and the indirect solvent processes.

Since carbon dioxide is the same ubiquitous and undisputedly “natural” substance that plants absorb and humans produce, and since, in most versions of the CO2 method, the flavor components remain safely in the bean throughout the process rather than being removed and put back in again as done in the Swiss Water process, carbon dioxide methods would seem to be the decaffeinating wave of the future.

Charcoal or Carbon Method
Is an indirect contact method which soaks unroasted beans in hot water to draw off the caffeine. The water solution contains caffeine as well as other flavor and aroma elements. The beans are separated and sent through a bed of activated charcoal or carbon filters to remove the caffeine. Next, as in other methods, the water containing the remaining flavor compounds is returned to the beans and then are dried. The coffee industry often refers to this decaffeination method as Swiss Water Process because a Swiss company originally developed and patented the procedure.

Methylene Chloride (direct contact method)
This is a solvent used in two ways to decaffeinate coffee. In the direct contact method, the green, unroasted beans are placed in a rotating drum and softened by steam for approximately 30 minutes. They are then repeatedly rinsed for about 10 hours with methylene chloride, which removes the caffeine from the beans. The caffeine-laden solvent is drained away, and the beans are steamed a second time, for 8 to 12 hours, so the remaining solvent can evaporate. Finally, air or vacuum drying removes excess moisture from the decaffeinated beans. Virtually no solvent residue remains after roasting the beans.

Methylene Chloride (indirect contact method)
In the indirect contact method, sometimes referred to as the water process, the green beans soak for several hours in a water/coffee solution at almost boiling temperature. Gradually the solution draws out the caffeine, as well as other flavor elements and oils, from the beans. The caffeine/water mixture is drained away and treated with methylene chloride, which absorbs the caffeine. The resulting mixture is then heated to evaporate the solvent and caffeine. Next, the mixture is reunited with the beans, allowing them to regain most of the coffee oils and flavor elements. The solvent never touches the beans.

Consumer concern regarding chemical residue resulting from this decaffeination process are common, yet unwarranted.  Keeping in mind that coffee is roasted at temperatures reaching 350–sometimes over 400 degrees Fahrenheit, brewing temperatures range between 190 and 212 degrees Fahrenheit, and methylene chloride has an evaporation point of about 104 degrees Fahrenheit the residue is non-existent in a brewed cup of decaffeinated coffee.

Ethyl Acetate (indirect contact method)
Using this substance to decaffeinate coffee is often referred to as a natural process because ethyl acetate is a compound found in many fruits, such as apples, peaches, and pears. This process is similar to the indirect contact method using methylene chloride, although ethyl acetate requires more time to absorb the caffeine. The process begins when green coffee beans soak in a heated water/coffee solution, which gradually draws off the caffeine and flavor elements. The solution is separated from the beans and treated with ethyl acetate, a compound that absorbs caffeine. A steaming process removes the caffeine-laden ethyl acetate from the water. The water is then returned to the beans, which reabsorb the flavor elements. Finally, the beans are dried.

NOTE: The United States Food and Drug Administration – FDA, has authorized by regulation the use of both methylene chloride and ethyl acetate for coffee decaffeination, According to an FDA report in the Federal Register, most decaffeinated coffee has less than 0.1 parts per million – ppm, of residual methylene chloride, 100 times less than The maximum level of 10 ppm allowed by the FDA.

See our collection of decaffeinated coffees at

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  • gicohen165

    How would we determine which method is used with specific BH Decaf coffees?

    • Barrie House

      We use all four decaffeinating methods depending on the origin and classification (i.e., organic or not) coffees. From the four the Ethyl Acetate and the indirect contact method using Methylene Chloride are more popular at Barrie House. But once again it really depends on the coffee. Thanks for the question!