Roasting Decaf Coffee – Some Key Things to Know

Even for an experienced coffee roaster, decaf coffee can prove challenging. Here’s why …

Decaffeinated coffee has been steadily improving in quality, and we think the time has come to let go of the “death before decaf” mentality. Almost all of the decafs we sell at Sweet Maria’s are decaffeinated using the Swiss Water Process (“SWP”) – this chemical-free method is gentler on the coffee’s organic structure and leaves much of the volatile compounds that affect aroma and flavor intact. For more info on the Swiss Water Process, check out our Swiss Water Process FAQ

Does the decaffeination process affect flavor? Of course – it would be dishonest to suggest otherwise. Even with improved processing, there will be a difference between the regular and decaf version of a coffee; we recently had the chance to compare the same coffee with regular and decaf side by side.

Comparing green coffees side by side; non-decaf top, Swiss Water Process decaf middle, and CO2 decaf at bottom.
Comparing green coffees side by side; non-decaf top, Swiss Water Process decaf middle, and CO2 decaf at bottom.

For this reason, roasters will rarely choose their best coffees to be decaffeinated – doing so would be like burning money! Luckily for Sweet Maria’s, we don’t face the same challenge and, as a result, all of our single origin decafs have a cupping score of 86 or higher even after decaffeination. For us, decaf is not a second-class citizen in our coffee line-up.

Given our high quality decaf, home roasters who drink decaf might experience an even larger jump in quality from store bought alternatives compared to those home roasters that stick to regular. 

Have we convinced you to try your hand at roasting decaf coffee?

Here are a few basic things to keep in mind as you get started: 

Why does my decaf coffee look darker while roasting?

Don’t trust color change as an indicator of roast level. Decaf coffee can get very dark, very quickly, but that does not reflect the actual roast level. In fact, decaf is already a darker shade than non-decaf coffee before roasting. While the Swiss Water Process does a great job of leaving the volatile compounds in the coffee intact, decaffeination weakens the internal structure of the coffee. Due to these changes, you’ll notice a different color progression – the beans will shift color from “green” (unroasted), to brown to dark brown very quickly, well before the coffee approaches first crack. Similarly, the surface texture of the bean will stay somewhat wrinkled, rather than smoothing out as you roast darker. 

What’s a good comparison when roasting decaf coffee?

Roast a similar, regular (caffeinated) coffee. Since judging the roast level of decaf can be difficult, we highly recommend roasting a regular, caffeinated coffee from a similar region and of the same varietal. Decafs tend to roast similarly to regular counterparts, despite differences in roast level indicators (color change, etc), so having a go-to profile for a regular coffee provides a helpful baseline for your reference. The decaf might turn out a tad lighter or darker than the “regular” coffee, but you will be in the ballpark.

Tracking the roast color changes of non-decaf, and Swiss Water Process decaf coffees.
Tracking the roast color changes of non-decaf, and Swiss Water Process decaf coffees. 1: Wet Process Ethiopia 2: Swiss Water Process decaf Ethiopia 3: Swiss Water Process decaf Brazil

Do decaf coffees have the same audible snaps as regular, non-decafs?

The snaps of first crack tend to be slightly softer in decafs, so you can miss them if you aren’t paying attention. Do your best to note the start of first crack, since timing your roast after this benchmark is one of the easiest ways to determine when the coffee has reached your desired roast level. 

I only roasted to City+, so why is my roast so oily?

It’s normal to see oil on the surface of your roasted decaf coffee. Like we mentioned a little earlier, decaffeination breaks down the organic material in coffee, which makes for a more porous cell wall. Because of the this, moisture escapes more easily during the roasting process, and oil will rise to the surface post roast, even when the coffee is roasted light.

What other ways can you monitor roast development?

Pay attention to smell. Once you’ve entered first crack, you’ll notice a sweet, almost vinegar-like aroma. This is a sign that your coffee is sufficiently developed – of course, you can roast darker if you’d like, depending on preference. Be sure to move past the yeasty, bready aromas noticeable in the drying stage or you might under-roast – this is particularly important if you’re aiming for a lighter, City/City+ roast with a decaf coffee. 

A pallet of Costa Rica coffee in GrainPro-lined jute bags that was decaffeinated by Swiss Water.
A pallet of Costa Rica coffee in GrainPro-lined jute bags that was decaffeinated by Swiss Water

Do decaf coffees benefit from a particular roast profile?

This concept is slightly more advanced, but helpful to keep in mind. If you have manual heat control, be careful with energy input during the drying stage and again at first Crack. Decaffeination weakens the internal structure of coffee and makes it less dense. Decaf coffee can take on heat more quickly as a result and, if you aren’t careful, first crack can take off, and quickly get away from you. A good rule of thumb is to pull back energy input (using heat or fan settings, depending on your roaster) just before hitting first crack. 

Can I expect similar weight loss from roasting as a non-decaf coffee?

The short answer is, no. The decaffeination process removes some of the coffee’s mass, and so the coffee stands to lose less weight during roasting than a non-decaf. Seeing even a couple % difference is totally normal. I’ve had decaf City roasts measure at 9-10% loss, whereas that would be 12% loss in a non-decaf. All coffees are different, and expect some variance in numbers.

What else can I do to improve on roasting decafs?

Take notes and learn by trial and error. Roasting theory is always helpful, but the best way to improve is through repetition. This goes for all roasting, but is especially important when roasting decaf. Time your roast and take careful notes of changes in color, aroma, and temperature (depending on your roaster). What changes to your heat, airflow, etc did you make throughout the roast? Always note when first crack starts and ends. Once you’ve had a chance to brew the coffee, write down your impressions – was this a successful roast? Does it taste underdeveloped, or overdeveloped? The more data you collect, the easier it will be to improve future roasts. 

26 Responses

  1. Just wondering. I have a two pound roaster. Can I roast half regular and half decaf together. Or will it change the flavor.

    1. Yes – you can definitely roast the coffee together. Decafs do color a little differently as they roast, but your non-decaf coffee can guide you to the roast level you want…

  2. Great question that introduces using the non-decaf beans as a guide. I can use that.
    It also produces and answer for me with some friends who like half/half coffee these days. I can roast it half/half. Just have to come up with a name for it. Ideas?
    “Low Dose Coffee” / “Half Caf” / “… ?

    1. There is not one answer, but it can be slightly less than non-decaf in drum roasters. The trick is in estimating the degree of roast … hence the article.

  3. When make a coffee blend, always roast the beans seperately then combine them. Since different beans will roast differently (especially decaffeinated beans, which roast quicker) you would get some over roasted and some under roasted if you roasted them together. If you’ve tried it and you like it, however, you can roast any way you like,

  4. I just roasted 2 small {4 oz) batches of Ethiopian decaf in my air roaster. I play a guessing game using visuals and smell ( since my hearing is diminished, the “crack” is not workable). I wasn’t aware that the roast color would be so different with decaf beans. Now I need to do a roast of similar “caf” beans and see what I notice. Thanks for the tips.

  5. I have watched several tutorials and went with one from Sweet Marie using an Air Roaster when I did my first roast and have been using the same instructions thus far. In the tutorial he roasted past 2nd crack, so now I am confused because the more videos I watch and the more I read I only see referrals to 1st crack. Should I roast to 2nd crack and do I wait until 2nd crack is finished before I stop? My times for roasting vary greatly from 8 minutes to 20 minutes (if going by crack). I roast both regular and decaf. Is there one basic rule of thumb to go by while I am figuring out how to do this?

    1. Hi Kathy,

      Thank you for your comment! First off, here is a helpful primer on the differences between 1st crack and 2nd crack, how to identify, and impact they have on flavor.

      The short answer to your question of whether or not you should roast to 2nd crack all depends on flavor preference. At 1st crack, roast flavors will be less pronounced, and flavor nuance comes through a little more clearly. Once you reach 2nd crack, roast flavors dominate the brew, and you have a more typical dark roasted coffee. One is not better than the other. It just depends on what you like!

      I hope this is helpful. Please feel free to chime in with any other questions you may have.

      Cheers,
      Dan

  6. I am new to roasting, and I’m using a popcorn popper. I have been weighing my beans before and after to get an idea of water loss. My scale only rounds to the nearest gram, and since I’m doing 100g per batch, this isn’t really accurate enough to differentiate between, say, full city and full city +, but I do it anyway. Generally 100g of green coffee produces 85-86g roasted coffee. I recently did a batch of decaf, using my normal method and normal time (7:30). 100g of green decaf produced 90g of roasted coffee. Additionally the roasted decaf beans looked very similar to my roasted regular beans, rather than looking darker as you indicate in the article. Confused, I threw the beans back in the popper for an additional 2 minutes, which produced very little change in color and no measurable loss in mass. (Maybe the popper never really got through the warm up period in that 2min). Is there any reason decaf beans would actually take longer to roast in a popcorn popper? And/or that they would lose significantly less mass at a given roast level than a regular bean? Should I conclude that my beans are less roasted than my regular beans? I have not yet ground them to see a grind color. Maybe that would answer the question..

    1. Hi Nancy,

      Thanks for chiming in on the post with your question. It’s a really good one, and something that should be clarified in the article. Decaffeinated coffee has already had some of the mass removed during processing, so there is a lower yield loss post-roast. Every decaf is different, but I would generally expect a higher return than non-decaf. (That’s a point often drive home to production roasters in a way to help justify the higher cost of decaffeinated coffee). Decafs are tough at first, and I think it just takes a few trial runs for anyone new to roasting them in order to find your footing.

      As for throwing the batch back in the Popper, while the roaster heats quickly, it will take the cooled beans a lot longer to come up to temp. It’s never ideal to put coffee back in the roaster, but doing it quickly – before the coffee has cooled – gives you the best chances of success.

      Hope this is helpful. Please don’t hesitate to reach out with any other questions!

      -Dan

  7. Dear Sweet Maria’s,
    As always, Thank you for your instruction. It helps going forward. I made a trip to your retail shop in Oakland in 2017 before my wife passed away and picked up a Hario hand grinder, but I had been roasting your coffees for three years prior. I now roast professionally and brew all my coffees using an Aeropress. The Decaf instructions really help. Thank you.

  8. Proud decaf roaster, been trying to get my SR800 totally dialed in. Decaf beans are def. a bit different but fun to roast once you get them!

    Coffee is my thyroid medicine, it has things that are very good for it. Caffeine no bueno, esp post covid

  9. So I just got the Fresh Roasted SB 800 home roaster, and am on about my 4th roast of decaf. A friend of mine who roasts regular coffee gave me this recipe as a starting point:

       1.    start F9 P4
        2.    1:00 F8 P5
        3.    3:00 F7 P6
        4.    5:00 F6 P9
        5.    5:30-6:00 1st crack
        6.    7:30 F6 P8
        7.    8:00-9:00 or less cool. Cool just before or at 2nd crack.

    I’ve been using 215g as Sweet Maria’s suggests for batch size.

    the problem with the above recipe is I WAY over-roast the decaf. So I’ve adjusted this recipe given the input from this page and the feedback in the comments:

        1.    start F9 P5
        2.    1:00 F8 P6
        3.    3:00 F7 P7
        4.    5:00 F8 P7 (adjust to P6 if needed)
        5.    5:30-6:00 1st crack
        7.    6:30-7:00 or less cool based on smell/color.

    When I do this, I don’t over-roast, but the origin flavor is not as developed as I would like.

    So my question is this: Should I be shooting for first crack around the 6 minute mark no matter what? And as this page recommends, slow the heat as I approach 380-400 degrees to ease into first crack? If I slow the heat more in the first 5 minutes, hence pushing first crack to occur later (7-9 min mark), does that mean I’d be in danger of “baking” the beans as opposed to roasting? In other words, should I use “first crack at 6 mins” as an anchor, and adjust around that?

    Thanks for all the help!

    Signed – new to this and confused,

    Mark

    1. Hey Mark, air roasting is by nature fast, and I wouldnt want to delay first crack too much. But I would also take a 5-6 minute rule for starting first crack as a ballpark figure. It’s hard to truly “bake” the coffee in a freshroast, or really any air roaster. So I wouldnt worry on that side of the equation. The simple problem with decaf is not stopping the roast too soon (because it looks dark) or stopping it too late, and going too dark on roast level.
      The fact is, decaf is really hard to roast, as you already know. In fact there are some decafs where just hearing first crack is difficult. I roasted one sample and there simply was no audible first crack! And visually it looks dark, so its hard to roast by color. I feel like, once you get used to the process, the aroma of the roast is quite a good way to verify the level, but that takes time to master.

  10. So I did another batch, this time with Columbia Supremo SWP. Took 5 mins to get to a 410 degree reading on the SB 800, and the smell went from that initial (I think people describe it as) “bready” flavor to an almost non-existent smell that started to smell roasted. I pulled it at that point even though it was only at the 5 minute mark and there was no audible “crack”. Looks on the lighter side, but may darken up a little over the next 3 days as I have it in a coffee canister developing/resting.

    I’ll let you know how it turns out.

  11. Roast came out horrible, and probably did damage to my grinder. Beans weren’t done and still very hard and dense. Made one batch of coffee and it was lightly tinted water :(.

    I guess I have to let it go longer after first crack. What should I be smelling? As I either smell nothing or it’s burnt?

    I also can’t seem to get the beans moving much in the air roaster. I thought decaf beans had less mass due to the decaf process, so I’m a bit befuddled.

  12. Just did a Roast in my Bullet R1V2 with your SWP Ethiopian Decaf. I had 1st crk about 8.30 min (199*C or 390*F) and let Develop for 1.30 (to 206*C or 403*F). Pulled a shot of espresso and it was already the best decaf I’ve had. I put it right in the freezer in a degassing coffee bag since I’ve heard it gets stale fast and I don’t drink it that often. But I may start to now that it taste like coffee instead of cardboard. Thanks so much for giving us a great option for decaf!

    1. I’ve been really into the decafs too, especially Ethiopia. In fact we have 2 more lots that are just arriving and 2 more coming a bit later, including another Ethiopia decaf with a lot of fruited notes

  13. Mark,
    I roast using a FreshRoast SR540. I have found that a setting of 7 7 8 seems to work well for most decafs. Comes out full City or full city + for most decafs. Beans are dark with just a bit of oil. I do not adjust at all during the roast.
    Gary

    1. Thanks Gary. I tried this method with an Ethiopian decaf. Flavor was mellow and not too developed. It tasted pleasant, but the roast was very uneven, probably because starting at a fan speed of 7 didn’t really move the beans around too much.

      I’ve been using this recipe now for a few decaf roasts, and depending on the bean and preference, I’ve been cooling anywhere from 11 to 12 mins:

      7 oz of green bean, in SB800

      1.    start F9 P3
          2.    2:00 F9 P4
          3.    4:00 F8 P5
      4. 5:00 F8 P6
          5.    6:00 F8 P7
          6.    7:00 F7 P7
      7. 8:00 F7 P8 til 1st crack (maybe longer?)
          8. After 1st crack F7 P8 until sweet smell, then cool
      10. Cool at 11:00

  14. I am moving into decaf for health reasons, so this article and comments are great. I roast on a coffee crafters fluid bed and mostly roast by temperature. 1st crack is always around 400 f and 2nd varies based on the variety, processing method and ambient air temp. I roast just to 2nd crack as I like the sweetness and body over the acidity. If I can’t hear the cracks, can I use the same temp mileposts that I’m used to?

    1. I have been roasting decafs a lot lately, and actually all of them seem to have audible crack at the same roast temperatures as non-decafs I am roasting. Timing seems the same too. I would say they are less clearly audible, and fewer actual pops. In the past we have had some decafs that were very hard to hear, or basically had no audible crack – so generally we like people to be aware that’s possible. If you are waiting for that sounds, and the coffees getting darker and darker – it can be a disaster. But all our current stock seems to be clearly audible

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