How is Coffee Decaffeinated

Decaffeinated coffee is a main stay in the coffee industry these days. Most of us drink decaf coffee on a daily basis, for one reason or another.

Decaf coffee is just there, but most of us don’t know how it is there. We assume the decaffeination process is easy. But as it turns out, removing the caffeine from the unroasted coffee bean is actually a complicated and (some say) unnatural process.

Coffee manufacturers can decaffeinate coffee using chemicals (such as methylene chloride), liquid carbon dioxide, or with the Swiss Water Process. In this article, we are going to go through each method of decaffeination to help you learn more about the cups of coffee you are drinking every day.

roasted coffee beans

How is Coffee Decaffeinated?

Coffee beans are decaffeinated before roasting by soaking them in liquids or gasses. The main decaffeination methods are: direct, indirect, Swiss water, CO2.

With the direct solvent method and the carbon dioxide method, no further treatment is required after processing.

With the indirect solvent method and the Swiss Water Process, new beans are introduced to the coffee saturated water. From these beans, only caffeine is removed and the other coffee properties largely remain intact. This is because the coffee water is already saturated with the coffee properties from the old beans, and it can’t absorb any more.

green coffee beans raw
Coffee beans are processed green for decaffeination.

What is Caffeine?

Caffeine is a natural stimulant found in various seeds, nuts, fruits, and leaves. The caffeine in coffee comes from the seed of the coffea plant. These seeds are contained within cherry like fruits. Coffee beans, therefore, are not beans at all. They are only referred to as beans because of their physical, bean like appearance.

Unroasted beans, or green coffee beans, are naturally lower in caffeine than regular coffee beans. Caffeine develops in the bean during the roasting process. Green coffee extract is therefore popular in the health industry for people who wish to get the benefits from coffee, without consuming too much caffeine. GCE is also higher in antioxidants, such as chlorogenic acid, which are present in coffee.

Why Should People Avoid Caffeine?

Some people wish to avoid caffeine for health reasons. For example, it is a good idea to limit caffeine intake if you have high blood pressure.

As a society, we are consuming more caffeine than ever. High amounts of caffeine are found in energy drinks and other sources that we wouldn’t necessarily expect. The FDA recommend that we don’t consume more than 400 milligrams of caffeine per day. Therefore, sometimes it can be useful to substitute regular coffee with decaf from time to time.

The 4 Coffee Decaffeination Methods

Coffee is decaffeinated using four main methods. These are:

  • The direct chemical method
  • The indirect chemical method
  • The Swiss Water Process
  • The carbon dioxide process

The Direct Chemical Method

Also known as the direct-solvent method, this was the first decaffeination process. It was discovered and developed in 1903 by German merchant, Ludwig Roselius. It consists of steaming and rinsing unroasted coffee beans in an organic chemical solvent repeatedly, until all the caffeine is gone. With this method the other properties of the coffee bean are left largely intact, so no further processing is required.

Roselius originally used the chemical benzene. However, after various health risks surrounding benzene came to light, coffee producers replaced it with other solvents such as methylene chloride or ethyl acetate. These chemicals are deemed completely safe by the Food and Drug administration (FDA). Beans decaffeinated in this way are also washed repeatedly to purge the coffee of any residual methylene chloride. There is sometimes some chemical solvent present in the beans after processing. However, the solvent has a lower boiling temperature, so the chemical is completely burned off during roasting.

The direct method is used by many companies, including Starbucks. The method is deemed unhealthy by some, however the amount of trace chemicals left after roasting is negligible. The coffee decaffeinated this way taste amazing. Here are couple of great Starbucks decaf coffees.

The Indirect Method

With the indirect method, the green beans are soaked in hot water first. The water absorbs the caffeine and all the other properties from the coffee bean. It is then this caffeine laden water that is treated with the aforementioned chemical solvents. This removes the caffeine. The same water is put into contact with fresh beans. Eventually, only the caffeine is removed from the fresh beans by the solvents, as the water is saturated and can’t absorb the other properties. It is this last batch of beans that is the finished decaf product.

Coffees decaffeinated with chemicals are cheap. The trade off for this is that the chemicals do also take some of the coffee flavors. Therefore, chemically decaffeinated coffees are not as tasty as other types of decaf coffee. This is especially true with the indirect method, where the beans aren’t decaffeinated directly with the solvent.

Green coffee beans decaffeinated with the indirect method are often referred to as ‘water processed’ due to the use of water in decaffeination compared to the direct method. This is not to be confused with the Swiss Water Process, which we are going to talk about next.

The Swiss Water Process

The Swiss Water Process is considered the healthiest and best way of making decaf coffee beans. For this method, green coffee beans are decaffeinated using only water. The Swiss Water Process removes the most caffeine. This method is expensive, and is reserved almost exclusively for organic coffees.

The Swiss Water Method is carried out exclusively by the Swiss Water Decaffeinated Coffee Company in British Columbia, Canada.

Much like with the indirect method, green coffee beans are soaked in liquid for decaffeination for the Swiss Water Method. This time, however, the liquid is water. Once the water is saturated, it is passed through a carbon filter. This specific filter is specially designed to trap the larger caffeine molecules, while allowing the soluble solids, which are smaller particles, through. The soluble solids are responsible for the flavor of the brewed coffee.

In the end this liquid contains a mixture of compounds that give coffee the flavor, but no caffeine. It is called green coffee extract.

The soaking process is repeated another time and the liquid will retain again all of the caffeine from the beans and some more soluble solids. The caffeine is again removed using a carbon filter and the liquid is used to soak some more beans. After a few subsequent treatments, the liquid saturates with soluble solids so it cannot extract them anymore. The only compound that will be extracted at this point is caffeine. At this moment all of the subsequent batches will be decaffeinated and they will retain their flavor.

This is my second favorite method, and not because of the method itself. The method is fantastic, but it tends to be a little expensive since we need to discard a few initial batches. There is no guarantee that the initial batches don’t end up mixed up with all of the good beans. Otherwise, your beans would be much more expensive.

The method is scalable down, compared to CO2 method. You can decaffeinate small specialty coffee batches, but this increases the price of the final coffee. The smaller the batch, the more expensive the bag on the shelf.

If you ever encounter a disappointing bag of Swiss Water decaf beans, don’t blame it on the method. Find a roaster that you can trust and stick with them. We recommend these Decaf Ethiopian Yirgacheffe from Volcanica, which are decaffeinated with the Swiss water method, and they qualify as gourmet coffee.

The Carbon Dioxide Method

This method, also known as supercritical carbon dioxide decaffeination, was invented by scientist Kurt Zosel. With this process, coffee is placed into an extraction chamber, where a mixture of water and highly pressurized liquid carbon dioxide are forced through it. The caffeine dissolves into the CO2. However, most of the other coffee compounds are insoluble in CO2, and remain in the unroasted beans.

This is a successful but expensive method of decaffeination, since the equipment is very expensive. The process is more cost effective for large batches, therefore, it is mainly used by large scale, commercial coffee companies where the equipment and processing costs are offset by quantity.

In my opinion, the CO2 method is the best at preserving the beans flavor and avoid chemicals in the decaffeination process. A great example of an inexpensive espresso decaffeinated with the CO2 method is the Lavazza Dek.

So what’s my Take?

Decaf espresso shot

If you can, I recommend you try and stay from the chemically decaffeinated coffees. Even in small amounts, it is my feeling that regular contact with these chemicals can be harmful to health over the long term. This is especially true if you’re drinking decaf on a daily basis, like most of us are!

Personally, I am a huge fan of the Carbon Dioxide method. I think it is the method that preserves the most flavor from the bean, in the healthiest way. I have never tasted a bad batch of beans decaffeinated in this way. Unfortunately, because this process is so expensive, it is only used for large scale, commercial coffees. It is still very unusual to find batch roasted, specialty coffee that was decaffeinated in this way. We live in hope!

That leaves us with the Swiss Water Process. Though this doesn’t preserve quite so much of the flavor, it is a worthy trade off. Many organic, specialty coffees are decaffeinated in this way and it is possible to get much higher quality decaf beans, compared to the CO2 method.

Overall, therefore, Swiss Water decaffeinated coffee is the clear winner. So have at it folks – check the pack of your decaf coffee to see how it is decaffeinated before you buy, then drink all the decaf you want! No need to worry about jitters or bad sleep; just enjoy a delicious, guilt free brew.

Photo of author

Dorian Bodnariuc

My name is Dorian and I am a former barista. I consume coffee in any form, as a beverage, in savory recipes and desserts. My favorite caffeinated beverage is the espresso. I love to share my coffee brewing knowledge and my geeky coffee research. This blog is one of the places I write about coffee. More about Dorian... If you want to learn more about this site and how I started it, check our About Me page, where I explain all about it.