Roasted this Ethiopian Limu 5 ways trying to understand how the ROR curve matches up with the tasting. I tasted roasts 3,4,5 about 3 hours after to see how things stood, notes below.
Roast 1
Large Crash and too quick a roast so going to try the ‘soak’ moving forward.
Roast 3
Prevented major crash. but still too hot, rode p4 for too long. also, now have been told ‘first crack’ is not when you hear the first crack, but when you hear ‘successive first crack’ i guess 3 in a row with no pause is the rec from Mill City.
Tasting
First time tasting coffee ~3hours after roast. This was the ‘best’ of the 3. sour into citrus to start but more nutty savory finish
Roast 4
This curve looked the best too me though it still crashes after 1C. maybe the ‘gas’ dip came too soon - definitely marking 1C too early so excited to try this again
Tasting
Assumed it would taste the best but very hollow. started similar sour to roast 3 but nothing after that, i guess that’s maybe clean, will see in 24 hours what it tastes like. 3 hour coffee isn’t really the great!
A very quick observation, looks like you leave your Fan setting at F2 for nearly all of these. You might also want to try adjusting that along with the Power. I’m still learning the Bullet too (coming from Fresh Roast 500) but I’ve been using both F and P settings to control the temps. Adjusting the F may help your control it from being “too hot” as you commented.
I need to do a session like this but haven’t had time to do more than 2 or 3 roasts at a time. But this is really good to see so thanks for sharing!
My limited experience had been that bumping from F2 to F3/F4 can actually increase ROR a little (convection heating?), past that ROR will deflect downward.
FWIW, I totally support setting the fan at a low value (high enough to clear most of the chaff) and leaving it alone, controlling RoR with power adjustments only. In these cases you need to cut power more in the mid phase. Shorten up the P6 and P5 intervals, and see if you can ride through FC at P4 or even P3 for this small batch.
I found that for 325g batches a more aggressive dip is needed, maybe P1 for 30 seconds, if you use one. But timing is difficult and crucial, and in the end the dip wasn’t needed for most beans after cutting the power correctly. That said, try turning on the IBTS-RoR. It doesn’t show the pre-FC spike in many of my roasts, which is really interesting.
These are pretty light roasts, which I’ve found sometimes take forever to develop mature flavor. Try storing some in a 1-way vented container and cup again in 10 days. Could be a pleasant surprise.
HTH! - Brad
PS: The BT sensor could be misleading, not well immersed with such a small batch. Another reason to rely on IBTS for temperature and RoR.
I’ve done at least a hundred roasts on the B. Roasting as many different seeds as I can. With all these different seeds I try to dial in on the ROR and most importantly must anticipate first crack and lower the temp before it happens and stop the spike. When to lower the temp is the key. I’m having fun roasting.
I like the comment from a roaster on the forum who has been roasting for twenty years and still is still chasing the taste of the best roast. Enjoy the journey.
I have noticed this too. I also tried skipping from F3 to F5 around first crack, and the increase in RoR was quite dramatic. My theory is that the increase in fan speed pulls heat from the outer part of the bean, so the temperature gradient from the bean center to the skin is higher, and that transfers even more heat to the outside more quickly, increasing the temperature.
Great test and I would second the idea of waiting 10+ days before you taste again. I find these fast roast and small batch size need a lot of post time roast to settle down.
I like the idea of using the ibts probe for RoR. I will try that.
Also note that batches under 300g are really hard to control so the fact that you are getting drinkable coffee is amazing, well done
so thanks for sharing!