The Science Behind Decaf Coffee

Posted on March 22 2022, By: Ana Ocansey

The Science Behind Decaf Coffee



According to Merriam-Webster, “decaffeination is the removal of caffeine”. According to Wikipedia, Decaffeination is the removal of caffeine from coffee beans, cocoa, tea leaves, and other caffeine-containing materials. Decaffeinated drinks contain typically 1–2% of the original caffeine content, and sometimes as much as 20%.  

Truth about Decaf 

Decaffeination is often associated with less flavorful coffee because it is a bit tricky to remove only the caffeine and not any of the numerous flavor chemicals, and decaffeinated beans are notoriously difficult to roast properly. This is why so many coffee drinkers prefer no coffee if they must drink decaffeinated coffee.

Death Before Decaf sign

Our Decaf 

Kaphiy, our coffee from Peru is decaffeinated using the Mountain Water Process. This, along with the Swiss Water Process, is considered the safest decaffeination process. 

One morning I decided to make my husband some of this coffee, which I liked since I tasted it. He asked where this coffee was from because he noticed the different tasting notes compared to the Cafenyolli and Cibao I normally make in the mornings. When I told him it was the Kaphiy, the decaffeinated coffee from Peru he was surprised. He was not surprised that I had given him decaf coffee! He was surprised that he could not taste any weakness or missing flavors in the coffee. He really did not miss the caffeine.

 Bag of Kaphiy coffee from Casa Dos Chica Cafe's website

The commonality in all decaffeination processes 

Coffee is always decaffeinated in its green (unroasted) state. 

As stated above, the greatest challenge is to try to separate only the caffeine from the coffee beans while leaving the other chemicals at their original concentrations. Coffee contains somewhere around 1,000 chemicals that are important to the taste and aroma so keeping the wanted chemicals makes it more difficult to remove the caffeine and keep the rest. 

Water is used in all forms of decaffeination since caffeine is water-soluble. 

Though water, by itself, is not the best solution for decaffeination. Water is not a “selective” solvent and therefore removes other soluble substances, like sugars and proteins, as well as caffeine. Therefore, all decaffeination processes use a decaffeinating agent (such as methylene chloride, activated charcoal, CO2, or ethyl acetate). These agents help speed up the process and minimize the “washed-out” effects that water alone would have on the taste of decaf coffee. 

Chemical makeup of coffee

4 Most common methods of decaffeination 

Direct Method:

The coffee beans are softened by either soaking in water or being steamed. When ready, the coffee beans are repeatedly exposed to a solution containing methylene chloride or ethyl acetate as a solvent. 

Usually, ethyl acetate is used for this method. This is considered a “natural” way to remove caffeine from coffee decaffeination process because the chemical is naturally found in fruits. 

This process goes on for about 10 hours. Once the beans have been fully exposed to the solution, they are usually steamed to get rid of any remaining solvent. 

Green Coffee Beans soaking in water liquid

Indirect Method:

This process begins by soaking the beans in boiling water. This draws out all the water-soluble contents, including caffeine and a lot of flavor compounds. The coffee beans are then removed from the liquid, which now contains all the water-soluble contents of the beans. 

Methyl chloride is then added to the liquid. When the liquid is heated, the methyl chloride evaporates the caffeine. Once all the caffeine is dissolved, the coffee beans are reintroduced to the mixture to regain the flavor compounds that were lost in the initial exposure. In this method, the coffee beans never contact the chemical. 

This process is the most commonly used method for decaffeination.  

In both of these processes, the solvents are rinsed or evaporated out of the green beans and further vaporize upon roasting. A tiny trace of the solvents (which are deemed safe for consumption) are present in the decaffeinated beans you purchase. 

Swiss (Mountain) Water Process:

This is based solely on water and carbon filtration. The coffee beans are first immersed in hot water to extract their caffeine and flavorful components. The initial beans are then discarded, and the resulting flavor-rich water (called “green coffee extract”) is passed through a carbon filter that is sized to capture only the large caffeine molecules. The decaffeinated green coffee extract is then used to wash and filter the next batch of beans. Caffeine is thereby filtered from the beans without recourse to chemical agents and without the beans losing many of their flavorful components. This is the primary method used to decaffeinate organic coffee beans. 

Mountain Water Process is a method of indirect decaffeination. This process is similar to the Swiss Mountain process. The process begins with a chemical analysis to determine optimal conditions, and then the beans are steamed and prepared for extraction. The extraction process uses a water-based saturated solution that removes the caffeine while keeping the coffee's flavor compounds in place. 

Mountain Water processing takes place in Mexico using water from the Pico de Orizaba Mountain while the Swiss Water Process, which originated in a small Swiss plant in the 1930s, today takes place at a single facility near Vancouver, British Columbia, using water from Canadian coastal mountains. 

Pico de Orizaba Mountain in Mexico

Supercritical carbon dioxide method:

This method uses carbon dioxide (CO2) under high temperatures and pressure to act like both a gas and a liquid. This supercritical CO2 reaches into the crevices of coffee beans like a gas but dissolves caffeine like a liquid. After the beans have been soaked in water (a process that expands cell structures and makes it easier to extract the caffeine molecules), they are exposed to supercritical CO2 for several hours. The caffeinated CO2 liquefies and evaporates, and the beans are then processed. Because this method leaves the carbohydrates and proteins intact, there is less change in taste as a result of decaffeination. 

Looking into top decaf products looked into 20 of the best-selling decaf coffee products on the market and discovered that 40 % of them contain harmful chemicals like ethyl acetate and methylene chloride, which are both used in paint strippers and thinners 

Now what? 

This does not mean you have to forget about your favorite decaf coffee or not drink coffee at all if you are sensitive to caffeine. Look for words like “chemical-free”, “Swiss water,” and “Mountain water,” on the package or online on the product details. These indicate a decaffeination process that doesn’t involve these harsh solvents. Do a little research into what you consume to learn more about their specific processes. A lot of information is at your fingertips, so use it.

Try this decaf and let us know what you think of the taste!


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