And this is what that RoR curve might look like:



I'm not sure I can reproduce that curve on my roaster. Maybe with a very small batch. Once I loose that heat momentum it will take a lot of BTUs to get it back up again.

It would be interesting to see what that coffee tastes like. I do not have high hopes.

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Almico wrote: I do not have high hopes.
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I don't either.

Thx Almico for those illustrations.
Why do you guys don't have high hope about that?

With a new bean, I usually target a linear, straight line declining RoR. I often have deviated from this while fine tuning and gotten better results. A good example is the Ethiopian Hambela DP show with a profile below.



This roast I intentionally stretched the dry and accelerated through malliard. With a straight line declining RoR, I was getting a lot of vanilla flavors that wasn't mixing well with the fruitiness. But this profile drastically reduced the vanilla making the fruitiness pop.

I guess my point here is the straight line RoR is a good starting point and may produce excellent coffee most of the time. There are exceptions to this rule. At least with my roaster.

I'm not sure about the Dietrich profile. I'd have to try it with a bunch of different beans. It looks a lot like the opposite that I did with the Ethiopian DP but with a quick ending. This profile seems to stretch the malliard and may result in more maltiness? There is nowhere that the BT falls or stays flat, so I would not discard it.

Another thing you may be overlooking here is that rapid increase in BT during development may not be real bean temp increase. Perhaps the fan was increased a lot resulting in more hot air hitting the BT probe. I can do this with my North 1K with a ton of fan. Good probe placement can help reduce it. Donno how the Diedrich probes performs.

The French Dude wrote:Simply know what's doable or not exept rao things...

Is that a crime?

I don't tell that Rao style doesn't make good coffe or not... I want to know if there is other style that make good coffee!

Thx

Rao stated the best, most memorable coffees he ever tasted shared same roast development attributes. That is far from saying this is the only way. But most people need simple rules to follow to get acceptable results.

I have 50# left of a Yemen coffee I picked up a few months ago. It was very expensive so I tried roasting in small batches at first. Turns out this is a hard coffee to roast in full batches and the small roasts were all over the place...RoR curves like my worst nightmares. One of the batches was a very intense strawberry bomb. The next one had no strawberry, but a huge bergamot note.

As I started to get this coffee under control I was not able to reproduce either experience. It is definitely a spicy coffee and very complex.

So yes, I believe attributes of a coffee can be pulled out using non-orthodox roast profiles, but at a cost. Both of the earlier roasts had significant dryness and lacked sweetness. They were great with a bit of maple syrup, but on their own, not very enjoyable.

From my experience, Rao's "rules" are not so much about getting the perfect profile to extract exotic flavor notes, they are about eliminating roast defects and maximizing sweetness. Without that, it doesn't really matter what else happens.

Almico wrote:This is what is referred to here:

<image>

Most of my effort has been to get Rao type results. He has argued that a plateau in the RoR curve and a following flick will produce coffee with less flavour than coffee roasted minus the plateau and flick, his video implied something like that. With an electric roaster getting such results has not been overly difficult loading 1.2 kg into a North TJ-067 in the City Roast range, various coffees. Italian roast on the other hand usually takes the shape of the Dietrich curve shown [Almico], with more development, running into the 30% range. Surprisingly to me this coffee is very popular, rewarding me with many commendations. Not that I care, because I do not like Dark Roast, do not drink it. A different roast style shown below lacks the flick--no curve upward--in development, but has a lot of plateau, mostly plateau of the RoR kind I would say. So not a Rao type profile either.

Agreed, totally.
For what it is worth, the TJ-067 E used above has 3 mm K type probes in the usual locations for BT and ET. That means I installed them same places as others on this forum have found to be best: BT on the drop flap, and ET on the chute. John on this forum drew the spots on a roaster and posted a photo (Thanks again!). Also I keep thinking as I roast looking carefully at RoR--this is what happens--I keep reminding myself that RoR is not even a measurement, just a bit of arithmetic based on time elapsed and the output of the BT probe.

roastimo wrote: He has argued that a plateau in the RoR curve and a following flick will produce coffee with less flavour than coffee roasted minus the plateau and flick, his video implied something like that.

<image>

In the masterclass I took of his he stated that while writing his book he was not sure if it was the plateau in ROR or the crash that accompanied it during first Crack that caused the "baked" flavors. He said that since then he has determined that the problem was most likely due to the crash and not the plateau although they are hard to separate because the plateau usually leads to a crash.