The Magic of Decaf Beans: How is Decaf Coffee Made? Explained in Simple English (and memes)

Decaf? How on earth do you decaf a bean? This is a complicated topic, so I've broken it down and explain it in plain English (and memes). Read on for some fun and seriously wacky stories!
chemical structure of caffeine

Ah, caffeine. A type of drug, a stimulant that physically contracts your blood vessels, pumps adrenaline through and heightens your senses. It works great for waking our zombie-minded colleagues in the morning, or desperate students pulling all-nighters (been there, done that). But, for those who are sensitive to caffeine, it can lead to some serious reactions, including withdrawal symptoms, diarrhea, headaches and severe shakes. And to our pregnant readers, caffeine is a big no-no. 

That’s where decaffeinated coffee beans come in, also called decaf for short! Why does decaf have a bad reputation? Does it really taste awful? Or are coffee snobs just being snobs again? More importantly, how is decaf coffee made? 

Out there, you’ll find plenty of super complicated journals about the in-depth reactions and processes taken to remove caffeine from coffee. It can get complicated really quickly – decaf is one complex beast. With the dusty knowledge of my chemistry classes, I’ve absorbed it all, processed it, and broken it down into plain English. It serves to give you a general understanding, in simple words for you and me, as to how decaffeinated coffee beans are made.

A Little Forewarning… 

Despite decaf seemingly always ending up as the butt of jokes, people drink a whopping 1 billion pounds of decaf beans every year. According to the Scientific American, that’s about 12% of the total coffee consumed worldwide. 

Yet very few are aware that decaf coffee is not actually free of caffeine! Despite the great lengths gone to produce decaf beans, it is damn near impossible to remove 100% of the caffeine from coffee beans – most decaf coffees are only about 97% caffeine-free. 

“Decaf coffees and teas have less caffeine than their regular counterparts, but they still contain some caffeine. For example, decaf coffee typically has 2-15 milligrams in an 8-ounce cup. If you react strongly to caffeine in a negative way, you may want to avoid these beverages altogether.”

U.S Food and Drug Administration, 2018

Hey, you’d be wise to trust the FDA’s advice: if you are indeed super sensitive to caffeine, it’s probably best to steer clear of it entirely in the first place. Don’t come crying to me after your toilet exploded from your reaction to caffeine – I warned you.

Try tea instead. Unlike coffee beans, certain teas can be 100% caffeine-free, as they are made from flowers or seeds that have no caffeine in the first place. 

How is Decaf Coffee Made? 

What is Decaf?

First, let’s look at my little definition of decaf:

Decaffeination is the process of removing caffeine compounds from raw, green coffee beans. The final product is called decaffeinated coffee, or decaf for short.

Removing caffeine from coffee beans takes place at the earliest stages of coffee production, way before they are roasted. They are treated when they are still fresh, green beans. 

how is decaf coffee made
ARRRRGH! Chemistry! Get this away from my eyes before I go blind!

The Concept of Decaf

A single coffee bean contains thousands of tiny, miniscule chemical substances, of different shapes and sizes. You’ll find all sorts of proteins, sugars, oils and acids that give the bean aroma, taste and flavour. Caffeine is just another one of these thousands of chemicals. 

Caffeine is a bitter compound that is naturally present in coffee. Removing caffeine itself is not particularly difficult. For example, plain old water can dissolve caffeine.

Wonderful, so I can just dunk a bunch of beans into water and get decaf! Easy!

Yes, buuuut it also happens to dissolve every other chemical substance in said coffee bean. And as we now know, these chemicals are super important in giving your coffee flavour and taste. If you remove ALL of them, the result? A horrible, disgusting decaf coffee.

The whole idea of decaf is to separate just the caffeine molecules from the other chemicals. Since these are microscopic molecules, this gets a bit tricky. You can’t exactly pluck them out by hand. The trick is to find a solvent* that acts on removing caffeine only.

*Solvent: a term for any liquid that can dissolve something. For instance, water is a solvent that dissolves sugar. 

Since ages ago, people have been getting really creative in trying to figure out how to do this.

Method 0: The OG Method

Story time! Once upon a time, in 1903, a German coffee boss named Roselius was waiting for his shipment of coffee beans to arrive. A giant wave swamped over the ship and soaked the beans with salt water. Instead of chucking the lot out and writing it down as a loss, old Roselius decided to still use it, and accidentally discovered that most of the caffeine had been washed away. 

We’re actually not sure if this story is true or a myth. It’s likely it has some basis in reality, but no one is sure just how accurate it is. 

Being the mad genius that he was, he attempted to repeat this in a factory to create decaf – and he succeeded! Using benzene, a solvent commonly found in paint and detergents (yum), he managed to remove the caffeine from coffee. Yipee! 

But then benzene was discovered to cause cancer. Ever since, it’s not been used anymore. Why? Because, um, well, I’ll let Doctor Ken Jeong answer that.

Back to the drawing board (sighs). 

Method 1: Using Solvents

Even though Roselius’ benzene was less than healthy (that’s putting it mildly), the basic idea and concept of it works. So the hunt was on for a new solvent, one that could remove just caffeine. Plus not kill you in the process – that would be a great perk too.  

After lots of brilliant science minds tinkering and experimenting, we found a few good solvents to use today, including:

  1. Methylene chloride 
  2. Ethyl acetate

I’m drinking decaf with weird chemicals in them?!

Don’t freak out. Ethyl acetate, as an example, is found naturally in apples, pears and certain wines. It’s also a common sweetener for candies and cakes, so don’t worry!

Fun fact: this is also known as the “sugarcane method”, as natural ethyl acetate is found in sugarcane, which is then used for making decaf.

So, how does it work? 

Option 1 is to steam the green coffee beans until they become soft and expand. Then, the beans are rinsed in ethyl acetate multiple times until the caffeine content is absorbed away. And lastly, to avoid you from drinking ethyl acetate in your coffee, the now-decaffeinated beans are steamed once more, which forces any remaining ethyl acetate to evaporate and vanish. Hoorah!

Option 2 is slightly more complicated. Instead of steaming, the beans are soaked in hot water. As we discussed, this causes all the chemicals to leach out from the beans, caffeine included, into the water. Now, you’ve got 1) what is essentially “concentrated coffee juice”, (the proper term is “green coffee extract”, but concentrated coffee juice sounds cooler), and 2) a first batch of tasteless, useless beans.  

You chuck the tasteless beans into the trash. They’re not going to be used ever again. Shame. Meanwhile, you mix the concentrated coffee juice with your chosen solvent (methylene chloride is most common) to dissolve only the caffeine in it. 

The last thing to do now is soak a second, brand-new batch of green beans into the concentrated coffee juice. Because there is caffeine in these new beans; but no caffeine in the green coffee extract, caffeine will leach out from the green beans into the extract. But since both the new green beans and the coffee juice have the same concentration of taste and aroma chemicals, the flavours will still stay in the bean. 

Phew! Hope you followed along just fine. Trust me, it gets a LOT more technical and complicated than what I’ve explained, but that’s about the gist of it. 

Method 2: Swiss Water Process

The Swiss Water® Process is arguably the most reliable method used, and produces coffee up to 99.9% caffeine-free. Many specialty or organic coffee roasters prefer sourcing their decaf beans from this method, as it does not involve the addition of any chemical solvents. Thus, it comes across as a “cleaner”, more natural decaffeination method.  

Wait, whaaaa-? So if solvents aren’t used to dissolve caffeine, how does it work? The answer: a micro-filter.

Green beans are also soaked in near-boiling water, just like the previous method. Again, you get concentrated coffee juice (I really like that name), but this time, instead of mixing a solvent in, the concentrated coffee juice is strained through a specialized filter made of activated carbon. This filter only allows things to flow through if they are small enough. It is designed to trap and separate the bigger caffeine molecules, whilst allowing smaller sugar and fat molecules to pass through. 

Then, throw out the old beans, bring in a new batch, and soak them into the caffeine-free concentrated coffee solution. Caffeine will flow out from the beans into the solution. The flavour, on the other hand, stays locked in. 

In my opinion, this really is one of the most fascinating coffee processes out there. Have a look at Swiss Water’s official website to learn more:   

Or have a quick watch of their teaser trailer:

Method 3: Carbon Dioxide 

The last method uses carbon dioxide as a solvent. That’s right – the air you breathe out. But not exactly in that state. 

When carbon dioxide is put under intense heat and pressure, its natural properties change. It enters a state called “supercritical”. Under this unlocked boss mode, the gas turns into a liquid, and can be used to separate different chemicals – including caffeine. 

Green beans are locked in a steel container, and this supercritical carbon dioxide is blasted into the coffee beans. Carbon dioxide binds to caffeine molecules and quite literally rips it out from the beans. Once most of the caffeine is gone, the carbon dioxide is removed from the steel container, leaving a nice, tasty bunch of decaffeinated beans. Again, it’s a heck lot more complicated than that, but that’s the rough picture of what happens.

This method is extremely expensive, as it requires a lot of resources to set up a facility capable of achieving such a feat. It also happens to be the most recently discovered method of extracting caffeine. A German scientist by the name of Kurt Zosel was playing around with supercritical carbon dioxide one day in 1967 and accidentally discovered caffeine dissolves in it. Man, the Germans really are incredible at creating decaf coffee from accidents. 

Can I Make Decaf Beans From Home? 

Unlike roasting, which you can get started with on a small scale from home, decaf is less feasible. Decaf requires the use of very specialized equipment which is ridiculously expensive and requires a literal warehouse of space. Your backyard isn’t going to cut it, I’m afraid.

In fact, because the process is so intensive and specialized, many roasters don’t actually remove caffeine from their beans themselves. The need to build an entire factory is beyond the reach of most small and medium roasters. Instead, they usually sign a contract with an existing decaf plant, or just import decaf beans directly. 

Don’t give up hope, though! Roasting used to be confined to large scale operations too, but now it’s very possible to get started with home equipment. So, possibly in the future, making decaf beans from home could be possible. Who knows, maybe you could be the next person to invent a new, cheap and easy decaf method?

So, yes, you can buy decaf green beans which you can then roast from home. But as for making the decaf beans, it’s a no. Sorry, folks.

Does Decaf Really Taste Bad?

Since decaf has such a bad rep amongst the coffee community, surely it must taste like garbage? Why else would it get bashed so much? In all honesty, it’s really like pineapple on pizza. People say they hate it, and cry about the oncoming apocalypse of decaf. But really, if you like decaf, think nothing of it. It’s all just banter and jokes. 

Some people make fun about the lack of caffeine, claiming it’s not real coffee. To that I say: if you’re judging the worth of coffee purely based on the caffeine kick you get, stick to energy drinks. Coffee is a drink that should be celebrated because it’s crafted with incredible taste and flavours that have journeyed long and hard to reach your cup. 

We’ve come a long way since decaf was first made with benzene. Taste wise, decaf flavours are getting better and better! Especially those you find in specialty coffee cafes and roasteries. These people run on passion. They truly care about what they’re brewing. 

Supermarket shelf decaf, on the other hand, I’d stay away. 

These days, decaf beans can produce real good coffee, without the adverse effects caffeine has. However, decaf is very, very easy to screw up. And just like regular coffee, if you over or under extract it, the taste will go downhill very quickly…

Decaf – The Bane of Every Barista Ever?

Baristas love poking fun at decaf. It’s true! But it’s not because they actually loathe it (well, most baristas anyway), it’s more to do with the fact that making good decaf in the busy rush of most cafes is really darn stressful. 

In specialty coffee cafes, baristas will be dialling-in their shots, weighing their dosage and timing their extraction. All while trying to juggle dozens of new coffee orders and rushing to serve customers. Making a good cup of joe means a lot to them. They have to make coffee fast without sacrificing quality. 

Decaf is somewhat trickier to keep an eye on than regular coffee. I don’t exactly know why, but having worked with many brands of beans before, decaf seems to have a mind of its own. After grinding, sometimes it gushes out like a waterfall, sometimes it drips out sooo slowly, despite not changing the grind settings. It very easily turns too sour or bitter. It’s hard to dial it in without massive wastage as well, since less people order it. This can throw off the flow of a barista and create a backlog of orders. And the one thing I hate more than anything else is having to serve a coffee I know is off to a customer. 

Some cafes give up trying to control grinding decaf beans, and resort to using pre-ground decaf coffee. Which is a terrible idea since pre-ground coffee is stale coffee. Yuck. 

As you can see, in the busy setting of a cafe, decaf can be quite a pain sometimes. But in the relaxed environment of my home, in the comfort zone of my brew bar, decaf can be awesome.

So the next time you order decaf from your cafe, be a little patient with your barista. You’ll be rewarded with your much-craved decaf coffee. (And please order a normal decaf coffee – much thanks!)

Decaf: Deciphered!

Wow, that was a wild ride! If you’re reading this, I’m super glad you have that inquisitive mindset of a true coffee lover. Decaf isn’t something that is easily explained in simple terms. I hope I’ve managed to really break it down into clear, concise chunks for you. This is just the starting ground, really. Equipped with this base knowledge, should you wish to do so, you can now head out and read up on much more in-depth articles and scientific papers on decaf. 

Or, the next time you pop by your local cafe, give their decaf a try. Don’t forget to appreciate the long journey and complex maze of a process the beans have had to go through to be decaffeinated. Above all, savour the taste as best as you can!

Sources and Further Reading