How to roast darker

Discuss roast levels and profiles for espresso, equipment for roasting coffee.

#1: Post by swder »

Hi all, what is the general rule to roast darker with smooth declining ROR? I have been roasting many batches and unable to roast any darker. All my roasts stalls (ROR becomes 0) before I would like to end the roast. I tried to use higher gas settings after the soak but that would cause my roast to be too fast. Any advice? Thank you.

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#2: Post by CarefreeBuzzBuzz »

You might want to share what roaster you are using and one of your current attempts. That will help people advise you.
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#3: Post by mkane »

Not knowing your control settings, off the top of my head I will say keep the heat in the machine as long as possible. Air control is the key.


#4: Post by N3Roaster »

I'd start by removing the constraint on declining rate and suggest not being afraid of cranking up the heat moving out of the range between first and second crack. Especially if you're planning to go substantially beyond the start of 2C, taking that part of the roast faster lets you get to the higher temperatures where the chemical changes you want out of a dark roast start while not spending so much time getting there that you completely destroy desirable flavors developed earlier in the roast.

The most popular roasting class I've been teaching lately has been one that explores lots of different profile shapes across a range of roasts, and my experience with that within the dark roast category is that what I've just described is preferred for dark roasts compared with the same coffee roasted to the same ending temperature following a strictly declining rate by almost all students in the class regardless of the coffee used for the exercise. If, after getting to that end point you want to try again to compare with what you've been trying to do, the experience from this different approach should give you a better sense of how much heat you need for that coffee in your machine going in and you can plot out a declining rate plan based on that which should make it easier to avoid premature stalling. Having that plan written down (or loaded into your data logger) will let you see where specifically you're deviating from the plan (if you're still having trouble), which makes it easier to troubleshoot those specific problematic points.
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#5: Post by Almico »

Once you get to a certain level of "dark", the declining RoR is irrelevant. The purpose of the declining RoR is to prevent baking and roastiness. If you're going well into 2C, you're going to get roasty coffee.

Best I can do with declining RoR is to just touch 2C. Technically, this is a medium roast by the Agtron scale. The trick is to retain as much heat during Maillard and hitting 1C at 20*/min+ instead of 15ish. That will leave you enough room to still reduce RoR. The risk is that coffees really like to take off when given that much heat. Keeping RoR pointing down is challenging.

Here is what I mean: This is my light roast template, the higher blue line is the target slope for getting darker.

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#6: Post by another_jim »

swder wrote: ... what is the general rule to roast darker with smooth declining ROR?
Um, impossible. If the bean temperature has stopped rising, because your ROR has smoothly declined to 0, the beans are not getting darker.

Think of your roaster as an oven. If you want to roast darker, keep your oven temperature (the ET) higher. That's all there's to it. As an added quality indicator. The darker you roast, the faster you wnat the roast to end (the interior of the beans should stay slightly lighter) Too high an ET may scorch the bans, so you may need to decrease the charge or raise the airflow as well.
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#7: Post by bicktrav »

The steadily declining RoR requires a Goldilocks gas configuration that gives just enough heat to carry you through first crack, but not so much as to cause a flattening or rise in RoR, which would inevitably lead to a crash. Basically your settings have to be precise in order to achieve a steadily declining RoR, and that precision doesn't allow for higher gas levels during maillard, which is what you need in order to roast dark. If you kick the heat up mid-roast, you will almost always cause your curve to flatten or rise, then crash. The only fix I'm aware of is a gas dip, but it's not a cure all. Anyway, I think about roasting dark the same way that others here do: it you're going dark, all bets are off. Smoothly declining RoRs are for light to medium roasts. Besides, once you char a bean, it really doesn't matter much.

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#8: Post by mkane »

How dark? Comparing this to SM's chart is FC+.

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#9: Post by bradm »

Yikes! What does that Shantawene taste like at 36F post-FC??

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#10: Post by mkane »

Like a campfire. My wife like her coffee burnt