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How is Coffee Decaffeinated?

Ever wondered how coffee was decaffeinated? As an avid coffee drinker myself I had too, so I set about finding out. It turns out that there are four methods to extract caffeine from coffee: the direct and indirect solvent methods, the Swiss Water method, and the Supercritical CO2 process. Read on to find out what each of these is.

best decaffeinated coffee

Discovery of caffeine in coffee

Caffeine is produced by coffee plants and works as a natural pesticide as well as to attract beneficial pollinators (the tea plant also produces caffeine).
It was discovered by a 19th-Century German chemist called Friedlieb Ferdinand Runge who was given some coffee beans to analyze by Johann Wolfgang von Goethe, the then-famous German poet, playwright, novelist, scientist, statesman, theater director, and critic.

Why would you drink decaf coffee?

Many coffee enthusiasts would argue that part of the reason for drinking coffee is to perk you up and give you that morning buzz. Additionally, caffeine does actually contribute an, albeit bitter, flavor to the bean and with decaffeination processes possibly denaturing compounds in the bean that alter the taste… Why on earth would you want to remove caffeine?!

Well, the remaining enthusiasts (about 10% in fact) find that their bodies and minds don’t react well to caffeine –  side effects can include anxiety, insomnia, diarrhea, excess sweating, racing heartbeat and muscle tremors.
And aside from the slight change in flavor, decaffeinated coffee is very similar in nutritional content to regular coffee so decaffeinated coffee is an excellent choice for those sensitive to caffeine but still want the health benefits from a cup of Joe.

How it used to be done

Germans discovered caffeine in coffee and it was the Germans who came up with an industrial method to remove it. When seawater swamped a shipment of coffee in 1903, it was found that the caffeine, but not the flavor, had leached out.
Ludwig Roselius pioneered a method to repeat the process by steaming the beans with acids and then using benzene, a solvent, to remove the caffeine.
Unfortunately benzene is carcinogenic (causes cancer), so the process evolved into the methods used today.

How it is done today

There are four methods used to extract caffeine from coffee nowadays and for all of them, decaffeination always takes place before the coffee is roasted – in its ‘green bean’ state. Do it after roasting and the resulting brew would taste like straw.
The beans are also usually moistened to make the caffeine more soluble.

Indirect solvent method vs. Direct solvent method

The first two methods are very similar; they both use a solvent (predominantly methylene chloride or ethyl acetate) to dissolve the caffeine and remove it from the coffee. The difference is in whether the solvent ever comes into contact with the coffee beans.
In the direct method, the beans are repeatedly soaked in the solvent to remove the caffeine. The beans are then washed with water and roasted to leave negligible levels of the solvent in the final product.
In the indirect method, the beans are soaked in near-boiling water which removes the caffeine (as well the flavor). The water is then removed and the solvent is added to selectively bond with the caffeine before the whole mixture is heated to evaporate the solvent and the caffeine.

The beans are then reintroduced to the water to reabsorb the coffee oils and flavors.

So are you drinking solvents when you have a cup of decaf? Well, probably, but not enough to worry about. The FDA allows a concentration of these solvents of up to 10 parts per million; the coffee industry usually produces decaf coffee to levels of about ten times less than this.
Additionally, the subsequent roasting process is likely to destroy much of the remaining solvents.

If you are still concerned about there being traces of chemicals in your decaf, you might prefer to drink coffee decaffeinated using one of the following two methods.

Swiss Water Method

The Swiss Water method has similarities with the indirect method seen above. The beans are soaked in water where the caffeine, flavors and oils are dissolved. The water is then passed through activated charcoal which is porous enough to capture the caffeine but not the flavors and oils which pass through. The resulting flavourful, caffeine-free solution is called ‘Green Coffee Extract’ (GCE).
The original batch of beans are discarded and a new batch of beans are soaked in the GCE. As the GCE is full of the flavor compounds, none of the flavor in the new coffee beans leaches out (as the concentrations are the same), but the caffeine in the coffee dissolves in the GCE. The GCE is drawn off and cycles through the activated charcoal again, while the decaffeinated, flavorsome beans are shipped.

Supercritical CO2 Method

The final (and most recently developed) method is the CO2 process. Here, the beans are held in a tank where highly pressurized, liquid-form carbon dioxide, is added. The CO2 then selectively dissolves the caffeine (but nothing else) and is removed from the tank of beans.
The CO2 is depressurised to turn it back into a gas, leaving solid caffeine behind. The CO2 can then be used in the same process again.

When decaf isn’t really decaf

Though these processes are very successful at removing caffeine from coffee, none of them remove every last trace of it – decaffeinated does not mean caffeine-free.
According to the US Department of Agriculture (USDA), coffee can be certified as decaffeinated if it is 97% free of caffeine. An average 12 oz cup of decaffeinated coffee still contains 5.4mg of caffeine – a regular cup would typically contain 180mg.

Final Thoughts

Caffeine was discovered and first extracted from coffee by Germans in the 19th century.
Caffeine has a number of side effects which some coffee lovers are more sensitive to than others. This led to a niche for decaffeinated coffee.
A process to decaffeinate coffee was discovered by accident and subsequently, four modern-day processes are used to remove caffeine from green coffee but retain or return the flavor back to the beans.
These are the direct and indirect solvent methods, the Swiss Water method, and the Supercritical CO2 process. 

Now you know how it is made, you’ll be grateful to know that companies have acknowledged the need for a decaf coffee (and coffee alternatives) that tastes as good as a regular cup of Joe. Check out our selection of regularly reviewed best decaf coffees.