Rwandan Struggle

Hey all. I am roasting Rwanda Nyamasheke Macuba and failing to get a good roast, particularly when used in my drip brewer. The roasts have had an astringency that I want to get rid of and a lack of sweetness.

I don’t think I have posted on Roast World before so please bear with me if the links and such don’t work…

I want to post a couple of different profiles that both have the astringency problem. I’ll note that I have been roasting with my Bullet for a year and it has been a struggle to get consistently good roasts.

This profile was very good with a Guatemalan but not so much with this Rwandan.

This profile is something I tried after reading a thread on RW where underdeveloped roasts were being discussed. The sweetness of this roast is improved, the astringency is a little better, but it’s definitely still there. Note: I am drinking it (drip) on less than 24 hours rest.

Thank you!

Hey there!

I believe that you’re going a bit too aggressive with your heat for your Rwandan roast. It makes sense that the Guatemalan works well with this profile due to Guatemalan beans typically being a super hard bean (SHB), meaning they are more dense. More dense beans conduct heat easier, allowing for roasting at quicker rates without under-roasting the center of the bean while charring the outside.

For your Rwandan beans, I would aim for a longer caramelization phase (middle of the roast) and then a quicker development phase (after 1st crack to the end). I’d also try with a lower charge temperature (to let the increased caramelization phase allow for the bean to be more uniformly heated) and potentially drop out your beans slightly sooner (to accent those fruit notes).

Let me know how it goes!


You may just need to let the beans rest. I generally consider roasts immature with less than 4 days rest, and have seen light Ethiopian roasts improve for two weeks. Hopefully yours are already brewing better today?

For me, grind size and brewing time also strongly affect astringency. Some beans/roasts (especially small hard Ethiopians) grind really finely so I have to adjust grinder settings to get the right size. Some beans/roasts also extract very readily, so I have to shorten brewing time and maybe dilute the brewed coffee with hot water to taste. Try playing with grind, dose, and brew time? Hope this helps, and sorry if this is super obvious stuff that you’ve already tried.


Thank you for making this point. I generally avoid coffees where Sweet Maria’s suggest a resting period, so I don’t think about it too much. You’re definitely on to something, this coffee became much more enjoyable after 4-5 days rest. I also set the grind 2-3 clicks more course on my Virtuoso, at least while the astringency was there, which helped, then set it back to my usual setting after it had rested. Thanks for the reply!

Thank you for your thoughts on this. I have probably leaned towards using more heat in my roasts because when I first started on the bullet I was having trouble with roasts stalling. Perhaps because I roast in my garage with the door open and the ambient temperature tends to be on the lower side. Despite using this machine for over a year I do not feel like I have a good command over it. I’ll see if I can work some of your suggestions into my next roast though!

My last roast was done your ideas in mind. I didn’t want to alter my profile too dramatically all at once, but I dropped the charge temp by 5C, stepped the P levels down earlier, and dropped the beans 3C sooner.

Even with just 48 hours rest, this is a much better roast. The astringency is mostly gone and I don’t have to grind a few clicks more coarsely to compensate for that issue. It is wildly fruity, that’s for sure! Thanks again for the ideas. I’ll continue to tweak it.

Rwandan roast 6

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I’ll just give you my opinion, since I’ve gone through all this. It won’t mean much, because everyone has to figure it out for themselves, since the conditions are not equal. It seems to me that your delta temps are pretty high. The last roast dropped a little, but, in my opinion, not enough. I think the main problem here is that you’re not giving them enough heat in the beginning and then trying to recover later, which, as the word says, is late. This could be why your roasts are underdeveloped and astringent. And that’s about everything that comes to mind after looking at the profiles and reading your posts.

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I honestly was not familiar with the meaning of delta temp so I had to figure that out. I hope that is not too revealing of my ignorance. This gives me another factor to think about. Thanks for the input!


It’s not revealing at all, because I had to learn too. I’m glad you found it helpful. Delta is important because a 1 minute development at 15°C delta is not the same as 1 minute development at 7°C delta. Of course, delta is the result of what you’ve done during the roast. Once you get to it, you can’t do much about it.