Decaf Fundamentals - Updated 1/2107
Decaf Fundamentals - Updated 1/2107
by Mike Strumpf and Christopher Schooley, photos by Swiss Water Process and Christopher Schooley
What Makes a Great Decaf - Mike Strumpf - Swiss Water Process
When thinking about how to make 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.
In-depth source information on where green coffee comes from is one of the tenants of Coffee Shrub coffees, and custom decaffeination affords us this same insight on non-decaf counterparts too. Deciding whether or not you want traceable information is an important aspect of buying any green coffee, and with decafs, knowing the origin info is very helpful.
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 the coffee is roasted dark in the end, right? With new much gentler decaf processing technics (such as water processing), volatile compounds are less disturbed, the raw ingredients going into the decaf coffee need to be reconsidered. There is not a best coffee farm or country for decaffeination. The best coffee for decaffeination is the coffee with the flavor profile that you enjoy! Having multiple decaffeinated coffee offerings means you can provide excellent decaffeinated coffee with many different flavor profiles.
The Swiss Water Process provides great clarity of flavor between the "before and after" decaffeination results. In our process, a decaffeinated coffee should taste like the original green coffee and little else. After each decaffeination run, we sample roast and cup the before and after decaffeination samples side by side, focusing primarily on any differences in cup qualities between the two. This clarity means that an exceptional coffee will make an exceptional decaf, and that is what most of us are looking for.
Outside of cup quality, physical bean characteristics can be important in selecting coffees for decaffeination. We 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). These three aspects of green beans are an important trifecta for both roasters and decaffeinators alike, though we might use the information differently. Knowing the relationship between those three physical characteristics can tell us if a green coffee is or is not viable for decaffeination, and as long as a coffee is fresh and sound there are generally not problems.
Roasting and Tasting Decafs Christopher Schooley
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, for the most part. 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. Basically the more you process a decaf, the more you break it down, and also if a coffee is already in poor shape, you're going to break it down even more. I think 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.
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. Again and Again, great decafs should taste fairly similarly to the regular counterparts
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.
This is more or less a guide to what you can expect from the Swiss Water decafs you buy from us, and elements to consider when roasting. With regard to roast approach, our instructions are on the general side as each roasting machine handles differently, and factors such as batch size will impact roast shaping possibilities. Whatever the case, starting with high quality raw material is one of the best assurances to yielding great results, which for us means starting with a great non-decaf coffee. Add to this equation the gentle decaffeination system of Swiss Water Processing, and you're rewarded with the makings of an excellent decaf cup.