Not everyone wants to drink caffeine, whether that’s due to sensitivity, pregnancy, or health reasons such as heart problems or gut symptoms. Some people want to drink coffee in the evenings without losing sleep over it.
The problem is that most decaffeinated coffees are cheaply produced and often tastes poor. Your decaf quality depends on the method your roaster uses to remove the caffeine. There are good methods which will keep the great taste — but you’ve got to know what to look for.
This guide covers everything you need to know about choosing the best decaffeinated coffee beans, including the pros and cons of different methods to remove caffeine, and the methods that produce good decaffeinated coffee.
What is decaffeinated coffee?
Decaf coffee is coffee that’s gone through an extra processing step to remove most of the caffeine. It’s impossible to remove 100% of the caffeine, but the best methods can remove 99.9%. (Contrast that with the worst methods, which can sometimes leave up to 20% of the caffeine still in the coffee!)
It's a bit like low alcohol beer. It can't remove all of the alcohol so there will always be some present. Little enough for you to not notice but you wouldn't want your airline pilot chugging pints before taking you across the Atlantic.
So which decaffeinated coffee beans should you buy?
To answer this, we need to understand the different processing methods. Here’s a breakdown of the decaffeinating methods and which one to go for.
Decaffeinated coffee: how is it made?
These are the five methods to remove caffeine from coffee beans — ordered from worst to best.
The first three methods use chemicals known as solvents to remove caffeine. These chemicals bind to and extract the caffeine molecule from the bean. There are two ways to do this with solvents: adding the solvent directly to the beans themselves (direct) or the soaking water (indirect).
WORST: Direct solvent method
The whole beans are steamed to open the bean’s pores, making it easier for the solvent to extract the caffeine. The beans are then washed with the solvent several times until enough caffeine has been removed.
Ever wondered why cheaper decaf coffees don’t taste as good as normal coffee? This is why: the direct solvent method is cheap and quick, but the solvents also tend to remove flavour and health-promoting compounds.
“Sugarcane” method
The so-called “sugarcane” method uses a natural solvent called ethyl acetate, which is extracted from sugarcane. As this is a naturally derived solvent, coffee decaffeinated via this method might be marketed as “naturally decaffeinated”.
Don’t be fooled, though. In reality, it’s cheaper and easier to make ethyl acetate synthetically using ethyl alcohol and acetic acid. So although it might still be called the sugarcane method, it’s not likely to be any more “natural” than the normal solvent method.
“Water” method
Otherwise known as the “indirect solvent” method, this method uses solvents but they don’t come into direct contact with the coffee beans.
The whole beans are soaked in water, which absorbs the caffeine and other water-soluble compounds. The beans are then removed, and a solvent is used to remove the caffeine from the water. The water is separated from the solvent by evaporation and the water is then reused for the next soak.
At some point, the water becomes saturated with the other water-soluble coffee compounds, meaning that the only thing removed in subsequent soaks is the caffeine.
However, studies show that this method still removes some water-soluble flavour compounds from the final coffee, negatively impacting the flavour.
Is decaf coffee produced using solvents bad for you?
There are no other negative health effects of the solvent method — direct or indirect. The solvent must be removed after the decaffeinating process. It’s impossible to remove all the chemicals, but they must be removed to safe levels.
The “maximum residue limits” for the solvents used to decaffeinate coffee in Europe are methyl acetate (20 mg/kg), dichloromethane (2 mg/kg) and ethylmethylketone (20 mg/kg).
Carbon dioxide
Another popular method uses supercritical carbon dioxide. That’s CO2 at high enough heat and pressure that it becomes partially liquid (i.e., above its “critical point”). Steamed coffee beans, water, and CO2 are mixed in a heated, pressurised vessel, which causes the caffeine to dissolve in the liquid CO2.
This method produces better-tasting coffee than solvent methods because fewer of the flavour compounds are removed. Most of the other coffee compounds aren’t soluble in CO2 so stay in the coffee beans.
BEST: Swiss water process
As you can probably tell, the Swiss water method was invented in Switzerland and uses only water to extract the caffeine. The Swiss water method removes the most caffeine — 99.9% — and produces the best-tasting decaf coffee. But this comes at a cost.
How does Swiss Water work?
A solution is made using water and green coffee extract, which mimics the composition of the green coffee beans being decaffeinated but without the caffeine.
When the coffee beans are soaked in the solution, the caffeine moves across the concentration gradient — from the beans to the water — until equilibrium is reached. The solution is then passed through an activated carbon filter to remove the caffeine. The process is repeated until enough caffeine has been removed.
The entire process takes 8-10 hours. This makes it difficult to scale, so most big coffee producers will use cheaper methods.
The Swiss water process removes fewer of the health-promoting compounds found in coffee and maintains the great coffee taste better than other methods.
Best decaf coffee beans
When choosing the best decaffeinated coffee beans, go for the Swiss Water method. This method removes the most caffeine and produces the most flavourful coffee. However, it’s expensive and hard to scale, so you’ll only find specialist small-scale roasters making decaf coffee using this method.
Our decaf is only produced using Swiss water method and we know our single-origin Brazilian beans keep their flavour best this way. It means that your decaf customers won't miss out on great coffee simply because they're skipping the caffeine.