How Is Coffee Decaffeinated? 4 Popular Methods Discussed
Coffee contains caffeine. It’s a fact!
But not all of us enjoy or can tolerate the charge coffee can give us, but that doesn’t mean we can’t enjoy a cup of joe.
While the coffee police might read this post in disgust, and even though I don’t personally drink decaffeinated coffee, there is a time and place for everything!
The question here is, how does the decaffeination process work, and can it leave you with a GOOD cup of coffee to enjoy late-night without the jitters?
While decaffeination does adversely impact flavor, no one wants a cup of Joe if it’s going to taste horrible, right?
Let’s jump in and find out how is coffee decaffeinated!
Does Decaffeinated Coffee Have Caffeine In It?
While the above might sound like an oxymoron, it isn’t as a stupid question as it may seem at first glance…
It’s important to note that while the decaf process removes MOST of the caffeine out of the bean, it does not remove it all.
According to the USDA, decaf coffee (in the US) is allowed to contain up to 3% caffeine and still be classed as decaffeinated.
Putting this in context, an 18oz cup of coffee containing 240mg caffeine would contain roughly 15mg of caffeine if decaffeinated.
Because the 3% allows for decaf to still taste (somewhat) like regular coffee and helps maintain a healthy antioxidant profile without using any weird additives you cannot pronounce.
Note – In the EU, the rules about caffeine content are much stricter. Decaffeinated coffee must contain less than 0.1% caffeine in green beans or 0.3% caffeine in processed dry coffee
Who Invented Decaffeinated Coffee?
The first person to decaffeinate coffee using a scalable methodology was a German called Ludwig Roselius, who was the founder of a coffee company called Kaffee HAG.
Ludwig had come across the key to the process by accident after receiving a shipment of coffee beans in 1903, which were contaminated with seawater, soon realizing they didn’t have the kick regular coffee has.
Using his technical expertise, he duplicated the process at an industrial scale using a solvent called benzene. Successfully creating the first well-established way to decaffeinate coffee at scale.
This process was patented in 1906 and named the Roselius process. However, this method is no longer in use today as benzene is now a known carcinogen.
Current Decaffeination processes have similarities
- Coffee is exclusively decaffeinated with unroasted green beans.
- Coffee contains over 1,000 different chemicals that impact its aroma and flavor. Regardless of the methodology, the idea is to attempt to remove the caffeine without disrupting the concentration of the other compounds in the coffee.
- Because caffeine is water-soluble, it is leveraged to act as a partial solvent in some part of the process each time.
- However, water alone is not useful because it cannot selectively remove caffeine from the coffee. Instead, each process utilizes an agent that decaffeinates the coffee while leaving most of the other chemicals intact.
How Are Coffee Beans Decaffeinated?
There are several ways to remove caffeine from coffee, but the most common methods involve soaking the bean in a solvent.
The solvent acts as an agent to remove the caffeine while leaving other compounds intact. Other methods use CO2 under extremely high pressure or good old osmosis.
While at first glance, some of these methods can issue a state of chemical phobia, it isn’t so strange once you understand how it works:
Solvents: Methylene Chloride and Ethyl Acetate
There are several ways to extract the caffeine using a solvent such as methylene chloride or ethyl acetate.
Methylene chloride is an industrial solvent, often used as a paint stripper. On the other hand, Ethyl acetate is an ester that can be derived from a variety of fruit, including bananas and apples.
Either way, the final product must contain less than ten parts per million of the solvent to be FDA legal. Whereas in the EU, the requirement is more stringent at less than two parts per million.
Direct Solvent Decaffeination
Green coffee beans are steamed and rinsed with the solvent, which acts as a paint stripper for removing caffeine from the beans. The coffee beans are then rinsed with water and vacuum dried ready for roasting.
The remaining caffeine-rich solvent is then distilled to remove coffee waxes and caffeine from the residual solution. This allows for the recovery of the solvent and for it to be reused in a repeat of the process on a fresh batch of unroasted coffee.
Indirect Solvent Decaffeination
Hot water is added to green coffee beans, which are then steamed and soaked in nearly boiling water for several hours.
This draws the caffeine out of the beans but also extracts some of the flavors and other compounds found in the beans.
The beans are removed from the water, and the solvent is added. The solvent draws out the caffeine from the water, and the liquid is then heated to remove the remaining solvent via evaporation.
As the boiling point of the solvents are lower than water, the solution leaves behind water and other coffee compounds.
The remaining water is then combined with the same beans to reconstitute the flavors in the coffee. This process repeats multiple times until the beans absorb the flavors.
As a result, the solvent never directly touches the coffee beans but decaffeinates them.
The Swiss Water Process For Decaffeinated Coffee
Unlike the previous methods, this process is chemical-free. Instead, it uses osmosis to output naturally decaffeinated coffee.
Developed in Switzerland (of course) in 1933 and primarily used by a company called Swiss Water based in Canada, a specialist in this decaffeination method.
The methodology is as follows:
- Green coffee is are received from growers and hydrated with local water.
- Green Coffee Extract (GCE) is added, which is a natural solution containing all the water-soluble compounds found in green coffee beans.
- The caffeine leaks out of the coffee, and the beans are dried, resulting in decaf coffee!
Where the GCE is made by placing green coffee beans in hot water, allowing the water-soluble solids to disperse out of the coffee, once the solids are dissolved into the water, the coffee is removed and discarded.
The liquid then goes through a set of charcoal filters, which selectively filters only the caffeine due to the size of the molecule. The remaining solution is GCE used in the cycle mentioned above.
supercritical Carbon Dioxide
This is the latest method in the decaffeination method but also requires the largest capital investment due to the machinery used.
Developed by a scientist called Kurt Zosel, it uses highly pressurized carbon dioxide, which turns the Co2 into a liquid and acts as a selective solvent.
Water-soaked coffee beans are mixed with the carbon dioxide in a (1000 pounds per square inch) pressurized extraction chamber.
The liquid carbon dioxide removes the caffeine from the coffee while preserving the other chemicals in the coffee.
The Co2 is then fed into another chamber, where it is depressurized and turns into a gas. The remaining substance is pure caffeine, and the Co2 is recycled to be repressurized and used again.
Which Decaffeinated Coffee Is Best For Taste?
While these sorts of questions are always debatable, most people agree that decaf coffee doesn’t taste the same as regular coffee.
Worse still, some decaffeination methods are considered even less desirable than others from coffee lovers. While personally, I don’t have an opinion on this as I don’t drink decaf, I did ask some other decaf fans.
It was clear that none of them (I asked seven people… Substantial sample I know!) enjoyed the taste of the Swiss process, with all of them agreeing it significantly impacts taste when compared to the other options.
Carbon dioxide is said to be able to maintain the most effective flavor of the coffee, but as the machinery is costly ($100k+) so it’s unfortunately not common.
As a result, the winner, by default, would probably be a solvent derived decaf coffee. If we were to dive deeper, I’d say methylene chloride because it doesn’t leave an unwanted aftertaste (a common complaint of ethyl estate acetate decaf).
The taste and aroma of decaf coffees may not be popular with caffeine aficionados, but there is undoubtedly a place for them here.
Who knows? I will probably wave goodbye to regular coffee more often as the older I get, the more I want coffee at night…but I abstain to maintain my sleeping pattern!
Ahmed Mir is the founder of Sip Coffee House. If he isn’t working, you can probably find him experimenting with different brewing methods, hanging out outdoors, or traveling.