Decaffeination Methods
Does decaffeinated coffee grow on trees? No it does not. However, if you are someone who’s interested in finding the decaf coffee that’s right for you or someone who’s just curious to learn more about the different methods of how coffee is decaffeinated, we encourage you to continue reading.
There are four primary methods of removing caffeine from coffee:
Direct solvent;
Indirect solvent;
Supercritical carbon dioxide process; and
Swiss water process.
If coffee beans are going to be decaffeinated, this must take place while they are still “green,” before roasting, to ensure the best cup flavor and aroma. If you are someone who drinks decaf, it means that you care deeply about the flavor of your coffee, so shouldn’t you also care about how it’s decaffeinated? Read on to learn more about the four decaffeination methods, as well as the pros and cons to each process.
Direct Solvent:
Most commercially produced coffees - around 70% - use solvent decaffeination. The two most common solvent agents used are either ethyl acetate or methylene chloride. With the direct solvent method, coffee beans are soaked in water or steamed to soften the beans and open their pores, which aids the decaffeination process. Then the beans are rinsed repeatedly with the chemical solvent - ethyl acetate or methylene chloride for 10 hours to remove the caffeine. Next, the caffeine solvent solution is decanted and the beans are steamed once again to remove any remaining solvent.
Ethyl acetate is considered to be more “natural” and safer than methylene chloride since it exists in small quantities in ripening fruits. However, it is not natural ethyl acetate that is used in the process, but a synthetic equivalent due to the tedious process and high costs associated with extracting natural ethyl acetate from ripening fruits. The synthetic variant of ethyl acetate is created by combining ethyl alcohol and acetic acid.
Indirect Solvent Method
For the indirect solvent process, the beans are first soaked in boiling water. This purges the beans of caffeine and the flavor compounds and oils that make coffee so desirable. Next, the beans are removed from the water, leaving only the water solution containing the caffeine and flavor compounds. At this stage, methyl chloride or ethyl acetate is added to the water solution. The solvent agent (methylene chloride or ethyl acetate) attracts and bonds to the caffeine molecules. The solution is heated and the agent evaporates, taking the caffeine with it. This leaves a solution containing only the flavor compounds and oils. The final step is to reintroduce the beans to the solution so that they can reabsorb the flavor compounds and oils that were lost during the decaffeination process.
Note about solvents: Some roasters advertise that they use a natural process called sugar cane ethyl acetate process to decaffeinate their coffee. While the molasses derived from sugar cane that is fermented to produce ethanol is a natural process, this is only half of the equation. Acetic acid is then added to produce the final solvent agent, ethyl acetate, which is a synthetic compound.
There is a lot of misleading information out there, so make sure you do your research and read labels carefully so that you know exactly what chemicals are or are not involved during the decaffeination process.
Supercritical Carbon Dioxide Method
This method has many names: CO2 (Carbon Dioxide) Method, Liquid Carbon Dioxide Method, and Supercritical Carbon Dioxide Method. Despite the difference in name, all describe the same process. This is the newest method used for decaffeination. The process was developed by scientist Kurt Zosel. The process uses CO2 in place of chemical solvents.
The first step involves soaking the beans in a stainless steel container, also called the extraction vessel. The vessel is then sealed and liquid CO2 is pumped into it at 73-300 atmospheres. At this pressure, the CO2 is dense like a liquid while still being a gas. The CO2 facilitates the same role as the methylene chloride or ethyl acetate in the solvent process methods, attracting and bonding to the caffeine molecules, leaving the flavor compounds and oils behind. Next, the CO2 is purged of caffeine by either transferring it to another vessel to depressurize, return to a gas-like state, and leave the caffeine behind or it’s filtered through activated charcoal. In this method, the caffeine-free CO2 can be recycled and used again for the next batch.
Swiss Water Process® Method
The preferred method of decaffeination for many organic roasters, the Swiss Water Process® method has been around since the 1930s. It was developed in Switzerland, but has since relocated to Vancouver, BC. The Swiss Water Process® facility is the only facility in the world certified organic by OCIA and Aurora Certified Organic. They are also certified Kosher by the Kosher Overseers Association. And if you’re wondering just how good this process is, at the end of the Swiss Water Process®, coffee beans are 99.9% caffeine free. Not bad for water.
What’s unique about this method is that water serves as the only aid in the decaffeination process. Said to be the “cleanest” method, there are no chemicals or other decaffeination agents used in the process. The Swiss Water Process® method relies entirely on solubility and osmosis to decaffeinate the beans.
The first step is soaking the beans in extremely hot water to extract the caffeine from the beans. The caffeinated water solution is then decanted through an activated charcoal filter to separate the dissolved caffeine molecules from the water solution. Smaller flavor compounds and oil molecules are able to pass through the filter unobstructed.
The water solution containing the flavor compounds and oils known as “Green Coffee Extract” is saved, and the caffeine-free flavorless beans are discarded. The Green Coffee Extract is reheated and used to decaffeinate the next batch of beans. Because the water already contains the flavor compounds and oils, only the caffeine dissolves in the flavor-saturated water solution (a.k.a. Green Coffee Extract). You now have decaffeinated coffee beans that have retained their robust coffee flavor.
Most coffees that use this method are labeled Swiss Water Process® , but not all. If you go to the Swiss Water Process® website, you can see a list of grocery stores in your region that carry decaffeinated coffees that use this method. At Class IV, we only use the Swiss Water Process because we want to provide our customers with the purist coffee experience on the planet.
