Decaf Coffee Fundamentals

An overview of our decafs and how to roast them

This decaf coffee fundamentals post sets out to provide background on the coffees we carry, as well as offer our roasting tips to get the most out of your decaf coffee.

When thinking about how to produce an excellent decaffeinated coffee you have to first focus on the coffee before decaffeination. That’s right, we said “excellent decaf”, a term reserved for coffees you’d be hard-pressed to know are decaf at all.

We find these exceptions most with coffees we’ve sent off for decaffeination ourselves, lots that were selected for high cup quality to begin with. It turns out, the original quality of the green coffee before decaffeination is extremely important, surprise surprise.

We like to think of decaf drinkers as simply “coffee drinkers”, in that each person has their own preference for flavor, acidity, body, and all of the other sensory aspects of a coffee. This wasn’t top consideration with decafs of the past, flavor being secondary to inexpensive processing. Plus, flavor matters little if in the end the coffee is poorly roasted, right?

The Swiss Water decaf method

The Swiss Water Process provides great clarity of flavor between the “before and after” decaffeination results. Because the volatile compounds are less disturbed with this method, the decaf should taste close to the original green coffee.

After each decaffeination run, the folks at Swiss Water sample roast and taste the before-and-after samples side by side, focusing primarily on any differences in cup qualities between the two.

Bags of Swiss Water decaf green coffee stacked on a pallet at the Sweet Maria's warehouse.
Bags of Swiss Water decaf green coffee stacked on a pallet at the Sweet Maria’s warehouse.

Outside of cup quality, physical bean characteristics are also an important factor in selecting coffees for decaffeination. Swiss Water analyze all coffees for their moisture content (percentage of the bean that is water), water activity (the state of energy of the water in the bean), and density (mass/volume) to make sure they can withstand processing.

These three aspects of green beans are an important trifecta for both roasters and decaffeinators alike, though Swiss may use the information differently. Knowing the relationship between those three physical characteristics gives some indicator as to whether or not a green coffee is viable for decaffeination. And as long as a coffee is fresh and stable, there are generally no problems with the decaffeination process.

Tips on Roasting Decaf Coffee

The classic decaf flavors that most people think of are the overwhelming maltiness, and in the worst cases, wet cardboard, but these flavors are generally the result of the original quality of the coffee itself or the intensity of the decaf processing. When the right coffee is selected and the process is carefully monitored, a good deal of the coffee’s volatile compounds that effect characteristics such as flavor and aroma should survive. As Mike says, a really great decaf should resemble the original non-decaf coffee.

The same holds true for how the coffee behaves in the roaster. A well processed decaf Ethiopia should behave more or less like a regular Ethiopia, except that the decaffeination process does affect the coffee’s density. Because of this you want to be sensitive to how you use your energy input during the roast, especially during the initial drying stage and after the 1st crack has really started to roll so it doesn’t get away from you.

A good rule of thumb is to try pulling back on heat as you near 1st snaps to minimize violent bean fracturing, and let the charge carry roast through to your final targeted roast development. On our Probat L-12 fully loaded (23 lb batch size), this means dropping the heat from 75% to 25% about 10 – 20 degrees before first cracks occur. This varies from one roaster to the next and will depend on batch size as well.

A side by side comparison of un-roasted and roasted Swiss Water decaf Ethiopian coffee
A side by side comparison of un-roasted and roasted Swiss Water decaf Ethiopian coffee

The major difference in roasting a decaf are the color change indicators. Color change is a big part of monitoring roast development in regular coffees, but because the decaffeination process alters the color of the raw coffee so drastically, the same color change indicators are no longer present.

One of the areas where this is the most problematic is at the very end of the roast. Decafs can appear much darker than what their actual roast levels are, and even begin to sweat some oils as the cellular structure is weaker from decaffeination. Even though a decaf may look dark, it might not actually be as dark as it looks since it started out a darker shade to begin with.

Most other physical and chemical changes are similar in decafs as in regular coffees, such as bean expansion, the 1st and 2nd cracks, as well as aroma indicators. The initial pops of 1st crack may be a little softer, but any well developed roast should have a distinctive finish to 1st crack.

The roast aromas during and after the 1st crack are some of the most telling indicators of roast development during this period. You should move past the cereal and bread-like aromas and begin to smell some pungency, almost vinegar-like aromas, but with sweetness to it.

Timing past the end of 1st crack is also crucial here. Use it along with your aromas to tell you when the coffee has reached your desired roast target. If you roast the regular version of that coffee to an end point of 20 seconds after the end of first crack, then do the same with the decaf version, and adjust from there.

Just because the coffee color is darker and some oils may be present, this doesn’t mean that you’ve engaged in dry distillation or are developing roasty flavors. This is one more reason why when we talk about roast level that the conversation has to be about more than just roast color.

Read more about the Swiss Water Process HERE

More tips and tricks on roasting decafs can be found HERE

Update of an 2013 article by Chris Schooley and Mike Strumph

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