Roasted a couple of fairly dark Sumatras today that have pretty linear RoRs. This has been a challenge for me for quite a while so I thought I’d share the profiles:
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I’ve been having pretty good luck lately starting at P8 with 325g batches. Was originally worried that this much power with such a small batch might lead to scorching or tipping but haven’t seen any yet. To be on the safe side with this soft Sumatra bean, the first batch above started at P7 for a minute before going up to P8. I timed the fan increase to F3 in anticipation of an RoR jump at FC, which seemed to work pretty well. Dropped just before SC.
The second roast above was a back-to-back roast and a honey process bean, so I dropped the preheat to 190C and increased the initial P7 interval. The fan increase to F3 had a noticeable cooling effect on the RoR, but this bean loves to spike at FC so I added a short power dip. Again seemed to work pretty well, and dropped this one with a couple of snaps of SC in the pan.
I’m optimistic about these roasts, but… time will tell. Also eager to hear what others think.
Thanks for the post Brad. I’ve had trouble getting to 2nd crack while trying to achieve the smoothly declining RoR (SDR) curve. These curves are textbook!
I rarely go to 219C, but have a new bag of Sumatra to roast for friends, and will use this as a template. It looks real good. Thanks.
RIght, I don’t roast this dark too often either. Hoping these Sumatras will be the Java half of some holiday crowd pleasing Mokka-Java, combined with that Ethiopian Shantawene!
First brews today after 3 days rest: both roasts were initially quite bitter, but smoothed out nicely upon cooling. Some nice sweetness and complexity emerged in the honey process bean. Both roasts taste much darker than they look. No visible oil spots yet.
I, personally, have failed to reach SC in a satisfactory amount of time with a declining ROR. I do 1KG roasts, and after a lot of attempts at going dark with a declining ROR, have now switched to a rising ROR a minute or so after FC. I read somewhere in Sweet Maria’s blog about a declining ROR not always being possible, especially for dark roasts.
Entering FC at an ROR that is 7+ (at least) gives me a a comfortable level of momentum to control my roasts thereafter.
Ditto here. BTW, what is your batch size?
I’m adding heat after FC as well. See https://wilsonscoffee.com/pdfs/roastkit.pdf for a discussion of how Neal Wilson designs his roast profiles. If you inspect his profile plans for medium and dark roasts, you’ll see that his RoR increases after FC as well.
Day 6 update: This roast of the honey process Sumatra bean (second pic in earlier post)
has completely mellowed, losing the off-putting bitterness from day 3. A few oil spots are showing on the beans now. The brew has great creamy body with dark chocolate and walnut, and light sweetness with notes of cedar and spice that strengthen in a long finish. Very happy with this one. It will not last long
Any thoughts on how you would approach a larger batch size 500g or 800g? Increase charge temp? Higher power start? I have been struggling going from smaller batches to larger batches and getting similar results.
It truly depends on the bean. I charge 1000g of Colombian Supremo at 270, P7, F2 and top out my RoR around 22 with a steadily declining RoR to 210 drop temp. Adjustments made along the way are
170 - P6
185 - F3
190 - P5
195 - F4
205 - P4
This is a recipe, and probably could be tweaked, but it is pretty consistent.
In contrast, I charge 1000g of a soft Brazilian bean at 220, P8, F2 which gets my RoR to about 23 and steadily declines to 205 drop temp. Similar adjustments along the way except higher finishing air.
To me declining ROR is not the proper way to roast dark, the concept “declining” is already telling you that you will be out of energy to push the coffee to second crack and beyond, to get enough energy after first crack and to get past second crack in a declining ROR profile you’ll need to charge probably at an absurd Temp that will get your coffee to yellowing and first crack to soon, you will get a dark roast but at the same time a BAD roast. Declining ROR profiles are beautiful for posting on instagram, but not all roasts can have a declining ROR.
I’ve actually been charging at a slightly lower temperature for a dark roast, aiming for a shallower RoR slope. The curves above were 200C and 190C preheats, vs. 210C for a standard light-medium roast. However, the big caveat here is that I’m only roasting these to the first snaps of SC. I’ve never roasted with the bullet to a stage where you get shiny oily beans like you’d buy from Starbucks or Peets.
Would you describe your preferred method in more detail with bullet profiles, and post some curves? Or maybe just point us at some of your dark roasts that you feel came out really good? I’m curious to try what you’re suggesting. Like you said, curve can be pretty but proof is in the cup!