Struggling with Colombian Caturra (Natural) on Bullet R1 V2 – Uneven Roasts & Scorch Lines
Hey everyone,
I’m roasting a Colombian Caturra (natural process) on my Aillio Bullet R1 V2, and I’m consistently getting uneven roasts with black lines or scorching on some beans. It’s really frustrating — I’ve tried so many tweaks, and nothing seems to fix it. Honestly, I’m starting to lose motivation to roast because of this one coffee.
Here’s what I’ve tried:
• Fan speed: Tried both F2 and F5 at different phases, didn’t see improvement.
• Charge temp: Experimented between 200°C to 300°C, no significant difference.
• Batch size: Went down to 350g, thinking it might help airflow or heat transfer — no luck.
• Adjusted heat application more gently during drying and Maillard.
Despite all that, I still get inconsistent results. IBTS readings seem normal, but the beans tell a different story.
Is this just a tricky natural Caturra? Is there something I’m missing in terms of airflow, turning point strategy, or charge protocol?
I’m struggling with this even with different beans different origins
Any help, tips, or shared experiences would really mean a lot. Thanks!
Yes, there are tricky beans that the Bullet struggles with. The first thing I’d suggest is to use the trier early in the roast, by which I mean the first minute. Examine the beans carefully every 5 to 10 seconds. You will notice a change in colour if the beans are getting scorched. Some beans will take on too much heat which will be difficult to get rid of later in the roast. I will link one of my latest roasts which you shouldn’t copy, because your roasting environment is different, just to give you an idea of the approach that might work with this type of bean. And it’s not really the Caturra or whatever, it’s the processing that makes beans behave this way. You might think that you have a dense bean, grown at high altitude, but the processing will have altered its structure, and it might be, for lack of a better word, “porous”, take on more heat and break down easier than a really dense bean would. It’s not a rule, because some highly processed and fermented beans roast normally, but there are a lot that don’t. When you look at the profile, you’ll see the beans will not let the heat go easily. But if you go with a high fan setting, you’ll go on a rollercoaster where you must lower the power, but the fan is making that impossible because with a high setting you should have the power set high too to balance it out. What I’ve learned with beans that present these challenges is that the fan is not really helpful because it requires more heat, and the beans themselves have already stored too much. Clearly, I might be wrong, but the eye and taste test say different. Here’s a photo.
I would also suggest going a little bit faster in the beginning and backing off earlier. Say increments of 2 every 30 seconds, instead of 45, and start backing off 30-40 seconds earlier.
