Dark roast is super bitter... new to dark

250G batch. Came out pretty bitter, bean has a lot more potential than this.

Walk me through your dark roast philosophy.

There are many ways to do this, but for me FC at 5:20 is too quick. I’d reduce the 230C preheat down to 200C or 190C for a dark 325g roast, and maybe even 180C for your 250g batch. Here’s a 325g roast that was right to the edge of SC:

What @bradm said. Also…

Probably unrelated but just in case: watch your brewing process as you can pick up bitterness by over-extracting. I drink exclusively dark roast that I drip using Melitta filters with a work-alike cone- I’ve faked myself out by not controlling water temp or by not sticking to my pour regimen.


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Alright, good advice here. Thanks for your chart. I read a little more, said dark is maybe good to start slow and pick up energy as you move into the roast. I was worried if I didnt have a lot of extra energy coming into first crack I would get baked out by beginning of second. However, your response has me wondering about your medium roasts now. Here is a Guatemalan bean I roasted this weekend as well, Roast World - Cup, grade, and analyze your coffee roasts in depth, (not labeled right in the chart), and I had first crack just before 5 minutes in. Huge flavor in this roast, chocolate notes really came through, thinking about easing back on this one a little bit to let the citrus notes shine through a bit more.

What do your medium roast charts look like? I find without an aggressive charge I usually get baked coming into first crack.

I’ve been charging a little hotter for the lighter roasts and cutting power more aggressively pre-FC to avoid a spike. Here’s a medium Colombian that had a ton of sweetness and a good balance of flavors.

That said, there’s no better proof than what’s in the cup. Curious to hear if your Guatemalan improves even more with a little fine tuning.

ill keep you updated, about to get about 150 pounds of it!

I have taken a different approach to Brad and the other Rao-istas on this site. I roast for espresso, and routinely go to 2nd crack and slightly beyond, to a drop temp between 255 for Full City+ to 265 for a light Vienna. My preferred method is to add heat starting 30 seconds after FC, which results in aROR with an S curve. Here’s a Guatemalan that I roasted recently, which showed nice chocolate notes and sweetness:

The other benefit to adding heat after FC is that you get to your drop temp more quickly, rather than crawling along at single digit RORs.

Another issue I have with adhering to steadily declining ROR is that on the Bullet, the ROR is tied to the Bean probe thermistor rather than the IBTS sensor, which is the sensor that I trust. If you look at my roast profile, the IBTS curve and the Bean curve are not parallel, so the ROR is not really telling me what’s happening with the IBTS curve.

Good luck with your roasts!

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This is pretty helpful, I like the non rao approach and will be trying this on my Sumatran for sure. I know I am showing some declining ROR curves on my roast profiles here, but I found that if I try to stick to Rao’s ideas orthodox style I end up baking the shit out of my roasts. I just shoot for keeping my IBTS line nice. I like the development on your dark roast at 30% too, I do not imagine wanted a super long development time to hit the darker profiles right. Ill get back to you!

The other other really nice benefit to @coffee_mook 's S-curve is keeping the weight loss down. I’ve seen flavors flatten pretty consistently when weight loss gets into the 16% range and above.

I also agree that the BT sensor seems intuitively less reliable than the IBTS for small batches. The new IBTS-RoR curve in RT 3.1.2 is VERY interesting to compare with the BT-RoR.

@coffee_mook This is very interesting roast profile. While I don’t go for dark roast this makes for interesting technique study. One question, you said your ROR is tied to the bean probe, is this the setting on your roast.world profile where we have to option of IBTS or Probe in the “Primary measure” dropdown?

Yes it is. Until Brad’s message, I didn’t realize that feature had finally been implemented. I look forward to being able to shepherd my roasts using an IBTS based ROR.