4 Ways Coffee Becomes Decaf - Which Method Is Best?

All coffee naturally contains caffeine, which is why we see coffees labeled as "decaffeinated" rather than "uncaffeinated" or "caffeine free." So how is caffeine removed from coffee, and what effect does that have on the resulting beverage in our mugs?

Decaf coffee first came about, as have many great inventions, by accident. In 1903, a green (pre-roasted) coffee shipment was soaked through with saline rich sea water, stripping the caffeine from the beans. The recipient of those beans, German coffee merchant Ludwig Roselius, sought to repeat the results on a larger scale. The method he developed used a chemical solvent called benzene, which is commonly used in paint strippers, plastics, and pesticides. While effectively removing the caffeine, benzene was later discovered to contribute to serious health problems like cancer. Its use as a decaffeinating agent has been abandoned in favor of four safer methods, all applied to green coffee beans prior to roasting. 

1. Methylene Chloride Method

Methylene chloride, or dichloromethane, is a solvent. Of modern decaffeination processes, this is the closest to Roselius' benzene method of the early 1900's. Exposure to methylene chloride in large amount, particularly when inhaled, poses serious health risks. However, the Food and Drug Administration (FDA) has ruled the trace amounts of methylene chloride remaining on the coffee  (less than 1 one-thousandth of a percent of the final product) pose no serious health risk for consumers. Coffee decaffeinated by this method is 96-97% caffeine free. Because it is the preferred decaffeination method in Europe, specifically in Germany, methylene chloride decaffeination process is also known as The European Method.

2. Ethyl Acetate Method

Ethyl acetate is a naturally occurring chemical in fruits like apples, bananas, and coffee (yes, coffee is a fruit). This decaffeination process is sometimes labeled as EA, sugar, sugar cane, or naturally decaffeinated. Any chemical residue is removed by steaming and later through the high temperatures of roasting. EA processing removes 97% or more of caffeine. While similar in method and safety, EA processing might be more appealing to consumers than methylene chloride simply because words like "sugar cane" and "naturally decaffeinated" look a lot less scary than words our minds can quickly (mis)associate with harsh chemical toxins of chlorine and methane. 

3. Water Processing Method

Developed in Switzerland in 1933, and commercialized in Canada in the 1980's, water processing is also know as Swiss Water Processing or Mountain Water Processing. Unlike the previous two methods, water processing does not involve the use of any chemical stripping agents. Green coffee beans are soaked in water to separate the coffee beans from the caffeine. The water also pulls out the flavor from the beans. (This would make for a very bland cup of coffee if the process ended here.) Next, the caffeinated, coffee-flavor-rich water is run through an activated charcoal filter, removing the caffeine. When new beans are soaked in this water, the science of osmosis happens, pulling caffeine from the beans without sacrificing any flavor. The result is a 99.9% caffeine free coffee. Because water processing is chemical-free, it is the most common decaffeination method for organic coffees.

4. Supercritical Carbon Dioxide Method

Under high pressure (1000 psi), liquid carbon dioxide can be used to extract caffeine from coffee beans. While effective to remove 96-98% of caffeine from the unroasted beans, this method is not cost effective for smaller farms and is utilized mostly in high volume, industrial settings. 

Which decaf method is best?

In regards to safety, all four methods above are approved for safe consumption. When it comes to flavor, the answer is more tricky. As with any coffee, processing is only one of multiple factors influencing the final quality of brew in our daily mugs. Others include the origin, the care with which it is cultivated and harvested, and the temperature at which it is roasted.

In my experience, EA and water processed decaf coffees have the most robust and developed in flavors. With water processing allowing coffee to remain certified organic, and EA being kosher and halal, both methods are a natural fit for specialty coffee roasters and consumers. 

Your best bet for a tasty decaf is a medium or light roast from a specialty roaster who knows how to adapt roasting techniques to best suit the nuances of decaffeinated beans.

We have our favorites. What are some of yours? Leave a comment below!

Cheers!

Amy, Founder of Red Eye Bistro

Special thanks to the following for contributing information to this article:
BBC News
Broast Tennessee Coffee Roasters
Cafe Imports
Coffee Confidential
Consumer Reports
The Food & Drug Administration, USA
The National Coffee Association, USA 
Scientific American
The Specialty Coffee Association