Tips for roasting decaf coffees

Selecting and roasting decaffeinated coffees
finnedoptimism
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Re: Tips for roasting decaf coffees

Postby finnedoptimism » Mon Jul 15, 2013 10:59 am

I'm new to roasting and roast mostly decaf. I started off using a popcorn popper this Spring and have now been using a SR500 for the past 2 months, with about 70 roasts total. Although the majority of my roasts have been decaf beans, I have done about 20 regular bean roasts.

Overall, I'm much more pleased with the decaf roasts in the SR500. However, I'm still having issues with the beans being over-roasted on the outside (or under-roasted on the inside). Although homeroasting has given me an appreciation for lighter roasts, I still prefer a thorough full city or full city+ for most of my beans and I just can't seem to get that quality with the decaf beans. Do other decaf roasters have some suggestions about techniques that help get the inside well roasted? Based on what I've read, I keep thinking that I should try to stretch out first crack, but I'm just not sure (for City+ to FC, first crack usually starts between 5 1/2 - 6 1/2 mintues and it typically lasts about 1 minute).

Based on my limited roasting experience, my observations about decaf beans are pretty consistent with others:
- virtually no chaf!
- on the SR500, first crack does seem a little bit more muted than with regular beans (no noticeable difference when using popcorn popper)
- in all of my decaf roasts, there is little-to-no time between first and second crack; most roast seem to go immediately into second crack (or perhaps this is something I'm doing wrong)
- I have been very pleased with letting my decaf roasts rest for about 12 hours although I have also brewed within a few hours of roasting
- like others have mentioned, my decaf beans (even at city +) often get spots of oil a few days after they've been roasted

Looking forward to your comments/ideas. Thanks!

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pieguy
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Re: Tips for roasting decaf coffees

Postby pieguy » Fri Jul 26, 2013 3:48 pm

Hey finnedoptimism. I know nothing about the SR500 so I don't know how much help I can be, but I'll try to give you a couple of ideas to try. First, how are you determining that the inside is under roasted? I'm assuming there is an unpleasant taste associated with these roasts. What is it like? Are you weighing the roasts to get the weight loss?

Now, a couple of things I could think of. I roast a lot of decaf, but I'm not claiming to be any kind of expert at it. But the one thing that I truly believe has made my decaf roasts taste better is treating them with more gentle heat during the drying phase and stretching out the time of the drying phase. I'm talking about the time where the beans are turning from green to yellow and before they start turning brown, when most of the moisture is escaping. I'm roasting with a Gene Cafe, which makes it pretty easy to do this, so I'm just not sure how you would go about it with an SR500.

The other thing is batch size. I don't know what batch size you are using, but a quick glance at SM's page on the Freshroast I find they suggest a batch size of 90g vs the manufacturer's recommendation of 120g. If you are using the larger batch size, you could be getting some uneven roasts which could be part of your problem.
-Ryan

finnedoptimism
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Re: Tips for roasting decaf coffees

Postby finnedoptimism » Sat Jul 27, 2013 4:43 pm

PieGuy, thank you so much for the feedback!

Based on your comments, I have a couple of things I'm planning to try on my next roasting session (in the next few days...although I'll have to do more research on the weight loss thing)...and I will post my results.

My under roasting observations are largely based on the how the color of the ground beans change (vs. how they look from my local roaster) rather than taste (although my beans tend to lack a fullness of taste that I associate with fuller roasts). The funny thing about decaf (IMO) is that even bad home-roasted beans are far superior to anything I get from a local shop or the store.

Very much appreciate the reply!

finnedoptimism
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Re: Tips for roasting decaf coffees

Postby finnedoptimism » Sat Aug 10, 2013 8:58 am

pieguy - your suggestion was right on! I roasted four batches each weighing 90g and each batch came out with no under-roasted beans. Each batch of beans (all decaf, but different varieties) lost about 10g after roasting.

Thanks again for the suggestions!

-finn

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pieguy
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Re: Tips for roasting decaf coffees

Postby pieguy » Mon Aug 12, 2013 10:07 pm

I'm glad the batch size helped your problem. I hope that decaf tastes great! If you like it then I wouldn't change a thing, but that amount of weight loss seems slightly low. I find that decafs tend to have less weight loss than regular beans, but 11% is pretty low if your measurements are accurate. So if you want to try extending the roast a little bit, it might be worth trying, but again if you like what you taste then you might as well stick with that!
-Ryan

laura541
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Re: Tips for roasting decaf coffees

Postby laura541 » Fri Nov 04, 2016 9:43 pm

If you’ve got to roast decaffeinated coffee, you’ve probably learned that it roasts altogether different than a typical green coffee. Decaffeinated beans look half-roasted to begin with, so there’s no way to judge by color. Decaf smells altogether different as it roasts so you can’t rely on the usual scent cues. Finally, it’s a but supine in terms of pyrolysis — the first crack can sound more like a typical second. And, insult upon injury, all the while that batch of decaf is roasting just a bit more quickly than regular coffee would. What’s a roaster to do?
Try this: simply add a few regular coffee beans to the batch. The caffeine content of three or four regular beans is inconsequential in the cup and these non-decaf beans prove exceptionally useful visual cues, they really stand out in a roaster full of decaf beans. When they don’t stand out anymore you know you’re very close to a completed roast. At that point, when your decaf begins to smell like just any ol’ coffee, quell the roast, it’s done.


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