How Do You Decaffeinate Coffee?

We’re all familiar with decaf coffee, but few of us question how it’s actually made. I was once under the impression that there’s no difference between regular coffee and decaf!

If you want to find out how the decaffeinated processes actually work, then you’re in the right place. We’ll take you through how it was first discovered that you could remove caffeine from coffee, and the different processes that are available today.

What Is The Appeal Of Decaf?

Coffee is known for being the beverage that gets you up and running on a morning, that gives you a boost, or keeps you going till the end of your night shift. This effect is caused by the stimulant drug known as caffeine.

With the many benefits that caffeine has, there are some situations and some people that prefer their coffee without it, and for good reasons. If you want a coffee later in the day, or you have some underlying health condition, then a decaf is the way forward. Even more so now when the quality of decaf is getting better and better.

Drinking a lot of caffeine can have negative effects on your sleep. With the half life of caffeine being 6 hours, it takes a long time for your body to get rid of it. So drinking a caffeinated drink past 2 or 3 oclock could affect the quality of your sleep. That’s why you would drink a decaf.

Yes, it contains caffeine, no more than 7 percent of that which is in regular coffee, but as long as you don’t have it right before bed you should be okay.

People that have heart conditions or sleep disorders should stay away from a lot of caffeine. The list of benefits may be longer when it comes to drinking regular coffee, but it’s all about the situation. Sometimes regular coffee can do more harm than good if misused, and so decaf can be a good alternative. Always consult a medical professional if you’re concerned about the effects of caffeine.

cup of coffee with coffee beans on the saucer

The Pioneers of Decaf

Friedlieb Ferdinand Runge

Friedlieb Ferdinand Runge was a German analytical chemist who first isolated pure caffeine from coffee beans in 1820. He did this at the request of the poet Goethe, who gave him a pot of coffee beans that were a delicacy a Greek had sent him.

Even though Runge was the first person to isolate caffeine, he didn’t explore or learn a lot about its chemistry. He also didn’t try to use the process for commercial use. That came about by our next pioneer.

Ludwig Roselius

Roselius was a German merchant who came up with the first commercial process to decaffeinate coffee in 1903. The way he figured it out was pretty lucky. He stumbled upon the process when his freight of coffee beans was soaked in sea water for a while. Roselius realised that the beans had lost a lot of their caffeine content, but retained all of their flavour.

The original process involved steaming coffee beans in various acids, and then using benzene as a solvent to remove the caffeine. However, it was later realised that benzene is a carcinogenic, and is now not allowed to be used to decaffeinate coffee. Roselius sold his decaf coffee all around Europe as Kaffee HAG, and later as the Sanka brand in the US. Cafe HAG and Sanka are now the worldwide brands of Kraft Foods.

Variations and Improvements

Since its discovery, there have been many variations, and completely different methods developed that decaffeinate coffee. Companies have been trying to create water-based and organic ways to make decaf coffee with some success.

The Swiss Water Method uses soley water and osmosis. It was developed in 1933, and doesn’t use any acids or solvents. It wasn’t used commercially until the 1980’s though by Coffex S.A.

Most recently scientists have been using carbon dioxide. Developed by Kurt Zosel, it uses CO2 which is heated and then pressurized to extract the caffeine. It’s quite expensive, but very effective.

coffee, coffee beans and ground coffee

How Solvents Work In Decaffeination

In the most simple explanation, solvents are added either directly or indirectly to remove the caffeine within the coffee beans. This has caused a few health concerns, especially in the early days. Toxic chemicals like benzene, dichloromethane and chloroform have been used in the past, but this is no longer the case. Methylene chloride and ethyl acetate are the chemicals of choice today.

Methylene Chloride (CH2Cl2)

Although this chemical is classed as a solvent, it has very, very low health risks if any at all. The Food and Drug Administration (FDA) has determined the solvent’s health risks to be essentially non-existent’.

In high quantities, there can be some effects like burning of the skin, or dizziness. The FDA’s regulations state that no food can contain ten parts per million (ppm) residual of methylene chloride. The coffee industry normally has levels at around one ppm, so it’s well below the harmful levels.

This level is recorded before the roasting process though. Methylene chloride evaporates at temperatures around 104F, and the roasting process can get up to 400F. It’s very unlikely that the solvent will survive these temperatures, so the end product probably has less than one ppm.

Ethyl Acetate (CH3CO2C2H5)

Ethyl acetate is considered to be the more natural solvent to be used during the decaffeinated process. This solvent can be found in ripening fruits like blackberries. It is therefore often that you’ll see the label ‘naturally decaffeinated’ when this solvent has been used.

However, collecting naturally occuring ethyl acetate is costly and time consuming. The majority of the solvents used to decaffeinate coffee are synthetic, though can be created using natural ingredients.

These are the two chemicals used in solvent based decaffeination processes, so let’s move on to how the processes take place.

coffee beans cooling after roasting

The 4 Processes of Decaffeination

There are two categories that we can divide the four processes into. Solvent based, and non-solvent based. Let’s start with the solvent based processes.

Indirect Solvent Process

This first process is very popular in Europe, more so in Germany, and so is often referred to as ‘the European method’ or ‘Euro prep’.

Firstly the coffee beans are soaked in boiling hot water for many hours. This extracts the caffeine out of the beans, but also the flavours and all those essential oils, which is not what we want.

The decaffeinated and flavourless coffee beans are removed from the water, and then methylene chloride or ethyl acetate is then added. These solvent molecules bond with the caffeine molecules. The liquid is then heated to a temperature where the solvent and caffeine evaporate, leaving behind all the flavours and oils in the water.

To get all those delicious flavours and oils back, the coffee beans are soaked back in the water for many hours. This is the reason for the name ‘indirect’, because the coffee beans don’t actually come into contact with the solvent at all.

Direct Solvent Process

To start off this process, the coffee beans are steamed, which opens up their pores. For the next ten hours, the coffee beans are placed in ethyl acetate or methylene chloride which removes the caffeine from the bean directly, hence the name.

The majority of the time this process uses ethyl acetate which is found naturally, therefore letting roasters advertise the decaf coffee as naturally decaffeinated.

It’s a very straight forward method, but one that puts people off due to the fact the solvent directly touches the beans. Keep in mind however, that every decaf coffee you buy will be less than ten ppm, and has an incredibly low, if any negative effect.

The Swiss Water Process

A natural and organic process to decaffeinate coffee is the swiss water process, which only uses water and osmosis.

There are no solvents used, and rely heavily on the solubility of the compounds found in coffee. This process is a little difficult to follow, so bare with me, I’ll try to explain it as simply as I can.

Firstly, the coffee beans are soaked in hot water, where the caffeine separates from the coffee, but so do all those flavours. This mixture of coffee beans and liquid containing caffeine and lots of flavour is poured through a charcoal filter, which acts like a net. It stops the large caffeine molecules from going through, while letting the flavour and oils pass.

So, now you have a pile of coffee beans without any flavour and any caffeine, and a tank of decaffeinated water with lots of flavour.

You throw the flavourless coffee beans away, and replace them with some fresh coffee beans that are full of flavour and full of caffeine. We take these new coffee beans and add them to the water, which has no caffeine and lots of flavour.

The water is then boiled, but this time less flavour molecules can dissolve into the water from the new coffee beans because the water is already packed full of flavour from the last batch. Only the caffeine is completely removed. So, we put this water through the charcoal filter again, meaning we’re left with no caffeine, and even more flavour.

After a couple of cycles of soak, drain, replace, repeat, the water is so packed full of flavour that the coffee beans and the water have the same density of flavour molecules. Basically, no flavour molecules leave the coffee beans because there’s no room in the water for them. But the caffeine does leave.

This water mixture is then used many times to remove the caffeine but retain the flavour of the beans to create lots of decaffeinated coffee.

Without a doubt this method is a very natural, organic and safe way to decaffeinate coffee, but it’s also the most labour intensive and isn’t cost effective. A lot of coffee beans get discarded, and there simply isn’t enough time to repeat this process for the high demand of decaf coffee.

Here’s a quick video that explains this process a bit easier:

Supercritical Carbon-Dioxide Extraction Process

This rather cool sounding extraction process is the most recent method developed of creating decaf coffee.

Carbon dioxide is commonly thought of as a gas. If you change its temperature and its pressure you can change how it behaves. For example, if you increase the pressure by up to 100 times that which is found at sea level, carbon dioxide starts to behave like a liquid. This state is called ‘supercritical

If you soak coffee beans in water, and force this supercritical CO2through them at pressure, it will take the caffeine with it out the other side, leaving all the flavour. The CO2 simply needs to be depressurized and can be used again.

This method can take this gas that’s so common in the atmosphere today and give it a use. But, the cost of pressurizing and forcing it through the coffee beans is expensive, and isn’t the method a lot of small coffee roasters will use to decaffeinate their coffee.

Why Is Making Decaf Coffee So Difficult?

First of all the extraction process is very hard. It’s challenging to remove the caffeine while leaving all those necessary flavours alone. Mess about with the flavours too much and you’re going to change the flavour of the coffee bean, and not for the better.

Secondly, it’s difficult to roast decaf coffee beans for two reasons. The coffee beans start off a brown colour even before they’ve been roasted, and so it makes it difficult for the roasters to control them. They respond inconsistently, and colour at different rates. Also decaf coffee contains less moisture, so they roast quicker than normal coffee beans. So the roasters have to account for a faster roasting process and have a challenging time judging the colour.

Here’s a video showing you a couple of tips on how to roast decaf coffee:

Final Words

The quality of decaf coffee has been improving over time, and the methods used try not to change the bean as much as possible. I don’t think that decaf will ever be of the quality of a regular coffee, but it’s becoming a much closer substitute for those of us that are sensitive to caffeine.

If you’re fancying trying some decaf coffee, we have an entire article reviewing the best decaf coffee!

Also, you can head over to NatesCoffee, where they have some amazing decaf Sumatra to try.

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Tom Bolland

Tom Bolland

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