Decaf Decoded: How Sugarcane (EA) and Water Processes Work

Decaf is a tricky problem. Caffeine is just one of hundreds of compounds in a coffee bean, and it's difficult (if not impossible) to pull the caffeine out without taking the other things that make coffee taste good with it. The coffee industry has two primary ways of trying to solve this problem (there are more, but most modern specialty decaf will use one of these two), and how it was decaffeinated will have some real effects in your cup.

Ethyl Acetate

Ethyl acetate is a solvent that selectively targets caffeine. More specifically, caffeine is soluble in ethyl acetate while most of the other flavor and aroma compounds in coffee beans are not. So when the coffee beans are soaked in an EA solution, that solution pulls the caffeine out and leaves the others in the beans. The soaking process is repeated until at least 97% of the caffeine content is gone from the beans. Because of this selective solvent, EA often leaves more of the original character of the beans intact than the water processes.

You'll also see EA called the "sugarcane process" because ethyl acetate is a natural byproduct of fermenting sugarcane. That "friendlier" name isn't covering up anything; ethyl acetate is classified as "Generally Recognized as Safe" (GRAS) for food use by the FDA, and any remaining residue evaporates during roasting since EA boils at 170°F, much lower than coffee roasting temperatures. 

But not all decaf solvents are the same; EA sometimes gets lumped in with another solvent process called methylene chloride (MC), which has been banned in the EU and restricted in California due to links to cancer. If a decaf coffee doesn't specify the method used for decaffeination, it could be an MC decaf, which I would recommend against, just to be safe.

Water Processes

There are two branded versions of similar processes that use water instead of a solvent to remove the caffeine from coffee: Swiss Water Process and Mountain Water Process. Both processes soak the green (unroasted) coffee beans in water until everything water-soluble (which includes caffeine) has come out of the beans. That water is called Green Coffee Extract.

They pass this water through a special charcoal filter that only traps caffeine molecules. What's left is Green Coffee Extract that's full of every water-soluble compound in coffee except caffeine.

The then-decaffeinated Green Coffee Extract is used to soak a fresh batch of green coffee beans. The caffeine in the fresh batch of beans wants to move from high concentration (in the beans) to low concentration (in the Green Coffee Extract). The other water-soluble compounds (acids, sugars, etc) are already saturated in the extract, so they don't move out of the beans.

The extract can be filtered again to remove the caffeine and reused to pull caffeine out of more batches of green coffee.

One benefit of these methods is that they tend to remove more caffeine than EA. Where EA is usually 97-99% caffeine free, SWP and MWP are 99.9% caffeine free. So if you're very sensitive to caffeine, choose one decaffeinated with these methods instead.

Water processes tend to produce cleaner, smoother cups than EA, though some of the origin notes, especially the acidic ones, can get lost along the way.

Why EA for our first decaf?

Primarily, I wanted to preserve the origin character. When roasting and cupping different profiles for our Colombia Buesaco EA Decaf, I picked up a lot of similar notes to our bestseller, Colombia La Unión, which makes sense since they're from similar regions. I did roast this one lighter, so it's brighter and has a bit more noticeable fruit character than our Colombia La Unión. I have nothing against the water processes, and we might even carry a water process decaf in the future. Either way, the process shapes the cup, and that's part of why we picked this one.