Onesto Coffee beans
500 g, Dark roast
Come to think of it, how is coffee decaffeinated?
20.2.2023
Translation: Jessica Johnson-Ferguson
Decaf. A product sipped mainly late at night to prevent your quality of sleep from suffering. To strip the beans of the caffeine they naturally contain, they need to be processed. This can massively impact their taste.
«Anyone want an espresso?» It’s 10 p.m. and I’ve just cleared the last plates from the table. Three of my friends say yes, two say no. «Or I won’t be able to fall asleep later,» one of them reasons. It’s something I’ve never understood, because I’m blessed with fantastic sleep. A privilege, I know. Although I don’t have any decaf in the house, it does raise a huge question:
how do you remove the caffeine from coffee beans?
I asked experts and soon realised there are different methods of doing this. However, according to Kaffeemacher:innen, a social business run by coffee experts, they all have three steps in common: moistening the beans, decaffeinating them with a solvent and drying them. These steps are all carried out before the beans are roasted.
The early days were toxic
Coffee was decaffeinated for the very first time in 1903 by Bremen-born coffee merchant, founder of «Kaffee HAG» and flaming Nazi Ludwig Roselius. He believed that his father’s death was caused by his high coffee consumption, or rather, by caffeine poisoning. That’s why he wanted to remove the caffeine from the bean. To do this, he presoaked the green coffee beans in salt water and then dissolved the caffeine from the fruit using benzene. The downside to this method? Benzene is toxic and carcinogenic. For this reason, it’s no longer used today.
However, the basic idea has remained the same to this day. In the so-called direct method, green beans are steamed before being soaked in dichloromethane, an organic chemical compound, for about ten hours. Alternatively, ethyl acetate, which also occurs in natural products such as sugar cane or bananas, can be used as a solvent.
The indirect process uses exactly the same solvents, but instead of the bean, the water is processed. Here’s how: green beans are soaked in hot water to extract all the water-soluble components. The caffeine is then extracted from this liquid using dichloromethane or ethyl acetate. New beans are then heated in this decaffeinated solution. This creates a solubility equilibrium. In other words, the same number of particles of a solid matter pass into the solution as particles from the solution that are deposited as solids. Put simply, the caffeine from the beans is dissolved and removed.
Chemical-free processes for more flavour
Although these chemical processes are comparatively inexpensive, they also take away a lot of the beans’ flavour. Many large, commercial coffee distributors resort to one of these methods, which explains why most decaf coffees don’t taste quite as nice as the regular kind. However, there are more expensive and lengthy processes out there that should hardly affect the taste of the bean.
The coffee roaster Onesto, for example, relied on the Swiss Water Process for a long time. «As we only offer organic Fairtrade coffee, we can’t use chemical methods anyway. More to the point, we don’t want to,» says managing director Fox Hardegger. The Swiss Water Process works the same way as the indirect chemical process, except that no solvents are used. The water that contains caffeine and other coffee components isn’t chemically decaffeinated, but with the help of an activated carbon filter. One disadvantage of this process is the relatively high cost, because the caffeine that’s bound to the activated carbon can’t be recovered and resold separately – to the cosmetics industry, for example.
Onesto has since switched to the same method that Vicafe uses to make its decaf house blend, namely with subcritical CO2. Carbon dioxide exists not only in the three known states of matter (solid, liquid, gas), but also in a fourth: at high pressures and temperatures, CO2 is liquid but has the chemical properties of gas. This is known as supercritical CO2, and some decaffeination plants around the world rely on it.
However, a plant in Bremen developed this process even further and now uses so-called subcritical CO2. The difference? The previously mentioned fourth state of matter is reached at a significantly lower pressure and temperature. «The coffee beans are washed with the subcritical CO2 at 23 degrees Celsius and 70 to 80 bar until the caffeine content falls below 0.08 per cent,» explains Ramon Schalch, managing director at Vicafe.
Reportedly, this just about maintains the structure of the bean, preserving its taste. And the method complies with Swiss organic standards. But it does also take much longer than the other methods. Namely, up to seven days. To recap, the chemical process takes just ten hours.
Isn’t decaf supposed to be better than regular coffee?
Alright, so there are very different methods of decaffeinating coffee which have a lesser or greater effect on taste. But above all, the coffee bean itself is the decisive factor. «Unfortunately, decaf is still treated far too often as a second-class citizen, with poor quality beans often being processed into decaf,» Schalch says. All this to say if the initial product is already of inferior quality – as is likely the case with many bulk coffee suppliers – the end product can’t boast top quality. If these are then chemically decaffeinated, which further impairs the taste, you really are filling your cup with dishwater.
When you think about it, this makes no sense. Aren’t the very people who drink decaf the true coffee aficionados? After all, they drink coffee because it tastes so good, not because it gives them an energy boost. Fobbing them off with coffee that tastes worse than its caffeinated counterpart seems almost mean. But that’s just my opinion.
Header image: Simon Balissat
My life in a nutshell? On a quest to broaden my horizon. I love discovering and learning new skills and I see a chance to experience something new in everything – be it travelling, reading, cooking, movies or DIY.