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All coffee beans start with caffeine in them. There are 4 main ways the decaffeination process is performed on unroasted (green) beans in order to remove the caffeine from the coffee.

Methylene Chloride Process

First, there is the chemical method using Methylene Chloride. This process is most often used for instant coffee. To start off, the coffee beans are steamed which opens the pours and allows the caffeine to come to the surface of the bean. Next, Methylene Chloride is applied to the beans which removes the caffeine. The beans are then steamed again and ready to be dried, shipped, and roasted.

Ethyl Acetate Process

Another process is the Ethyl Acetate Decaf Process, also called “naturally decaffeinated” or “sugar cane decaffeinated”. Basically, when a fruit or sugar cane ripens it produces ethyl acetate in small amounts. This solvent has been found to remove caffeine through a similar process to the Methylene Chloride process. Although this is found in nature, it can also be made synthetically and be used for the decaffeination process.

CO2 Decaffeination Process

A more complicated process is the supercritical fluid extraction process. This process uses pressurized carbon dioxide to remove the caffeine from the bean. The CO2 gets released along with the caffeine, a charcoal filter “catches” the caffeine, and the CO2 is reused. It’s a win, win! It is good for the environment and does not involve chemicals.

Swiss Water Process

The final process I will discuss is the Swiss Water Process. This is a common process that many quality roasters prefer. A batch of green coffee beans is soaked in hot water, removing the soluble material which is then filtered through a carbon filter. The carbon filter only removes the caffeine from the liquid. This liquid (which contains all the natural soluble material found in coffee beans, except the caffeine) is then used to soak the next batch of green coffee. This allows the fluid to draw out the caffeine from the beans while leaving the soluble material! This way the natural complex sugars and chemicals of the actual bean remain relatively untouched, producing a quality cup of coffee.

Sources:

What is Swiss Water Decaf Process Coffee? (decadentdecaf.com)

What is Decaf Coffee? A Guide to Decaffeinated Coffee (decadentdecaf.com)

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