how is coffee decaffeinated?

If you like a cup of coffee without the caffeine, lift your mug in honor of Friedlieb Ferdinand Runge the next time you boil the kettle.

Runge was a 19th-century German chemist who caught Goethe's attention as a poet and statesman who was also a keen science scholar. Runge's pioneering research into belladonna, also known as nightshade, was well-known to Goethe. Runge had discovered the compound that, when swallowed, caused the eye muscles to dilate.

Goethe had recently obtained a case of coffee beans and demanded that Runge conduct an examination of the beans. Caffeine, which Runge discovered, is arguably the most commonly used medication in the modern world.


Caffeine can be contained in a variety of beverages and foods, including tea and chocolate, but it is inextricably associated with coffee. It's a stimulant and an appetite suppressant, making it a successful pick-me-up for students preparing for tests, nightshift staff, and anybody else who wants a boost.

Caffeine, on the other hand, has a dark side.

Anxiety, insomnia, diarrhoea, excessive sweating, racing heartbeat, and muscle tremors are all possible side effects. For certain people, the benefits of coffee are outweighed by the harmful effects of caffeine.

Is it possible to eliminate caffeine from coffee? Yeah, as any supermarket aisle would tell you – but the method isn't as easy as you would expect.

Another German, Ludwig Roselius, the CEO of the coffee company Kaffee HAG, was the first to discover a functional decaffeination process. Roselius stumbled upon the answer to decaffeination by chance. In 1903, a coffee shipment was flooded by seawater in transit, eliminating the caffeine but not the taste. Roselius devised an industrial process for reproducing it, steaming the beans with different acids before extracting the caffeine with the solvent benzene. It was then that decaffeinated coffee was born.

Since benzene was discovered to be a potential carcinogen, researchers searched for new ways to remove the caffeine from the beans while preserving the taste.

According to Chris Stemman, executive director of the British Coffee Association, several of the methods used in the early days of decaffeination are still in use today. However, the technique isn't as easy as you would imagine.

Stemann explains, "It isn't done by the coffee companies themselves." “It's achieved by decaffeination firms that specialize in it.” Many of these corporations are headquartered in Europe, Canada, the United States, and South America.

You would think that roasting the coffee, grinding it into the desired powder (espresso, filter, or instant), and then beginning the decaffeination process would be easier. According to Stemman, this is not the case.

“If you wanted to decaffeinate roasted coffee, the effect would be something that tasted like straw. As a result, 99.9% of decaffeinated coffee is still processed at the green coffee stage.”

Coffee can be decaffeinated in a variety of ways, the most common of which is to soak it in a solvent such as methylene chloride or ethyl acetate. Methylene chloride is a paint stripper and degreaser that can also be used to extract caffeine.

Meanwhile, ethyl acetate is a natural fruit ether that is usually made from acetic acid, which is the building block of vinegar, and is often used to make nail polish remover (it has a distinctive sweet smell, much like pear drops).

After soaking in water, the beans are immersed in a solution containing one of these solvents. The solvent then pulls out the caffeine.

The solvent-laced water is then reused until it is full of coffee flavorings and compounds – almost similar to the beans except for the caffeine and solvent. Since the beans are basically immersed in a distilled coffee essence at this point in the process, they lose very little flavor.

While soaking coffee beans in solvents does not seem to be a particularly safe practice, both of these agents have been given the green light. The US Food and Drug Administration reported in 1985 that the risk of methylene chloride posing a health risk was "essentially non-existent." (Residual methylene is permitted by FDA rules up to 10 parts per million, but coffee decaffeination solutions are typically one part per million.)

Water is used in two other methods. The Swiss Water method involves soaking the beans in water, then straining the caffeine-rich solution (which is also full of flavor) using activated carbon, which captures the caffeine. The method was developed in Switzerland in the 1930s and first used commercially in 1979. It became famous because it was the first decaffeination process that did not involve the use of solvents.

Another process, according to Stemman, involves the use of "super critical carbon dioxide." Soaked beans are placed in a stainless-steel extractor, which is then sealed, and liquid CO2 is blasted into the beans at pressures of up to 1,000 pounds per square inch. The C02 binds with the caffeine molecules, pulling them out of the unroasted bean, much like the Swiss Water system. After that, the gas is removed and the pressure is reduced, leaving the caffeine in its own chamber.

It's a clever system, but it has one major weakness, according to Stemman. “It can be highly costly.”

According to Stemman, decaffeination became even more popular as instant coffee became a staple. However, the first models of instant decaf coffee were not a big hit.

“If you go back 20 or 30 years in the UK, we [were] truly a country of instant coffee drinkers,” he says. “And the one thing about instant coffee was that it didn't taste like coffee. What worse was decaffeination.”

According to Stemman, as people have become more accustomed to high-quality coffee – the UK, for example, now has over 24,000 coffee shops – coffee-making firms have been forced to find ways to enhance flavor even in decaffeinated instant coffee.

“Decaffeination is a difficult chemistry problem, which is why there are so many advanced companies doing it.”

The centennial of decaffeination, which occurred in 2006, was characterized by little fanfare. Although 15% of coffee drinkers preferred decaffeinated brews in the 1980s, that number has dropped to about 8% today in the UK, even as the quality has improved.

Is Stemman a decaffeinated coffee drinker? “In general, no; if I don't want the caffeine, I won't drink coffee or tea.”