Airflow versus Stretched Dry and Ramp

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
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cimarronEric
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#1: Post by cimarronEric »

cimarronEric wrote:
I just got some of this as well. Are you willing to share how long your dry vs. ramp times were? I was going to start with something like a 5-3-1.5 dry, ramp, development - but I'm open to suggestions and other's experience.
the_trystero wrote:
Yep, the 1st profile was 10:00 with similar ratios to the 2nd one.

The 2nd profile was 5:30 - 4:00 - 1:30.

Charge temp of 390 degrees, on the Diedrich airflow through the cooling bin til 9:00, then through the drum the rest of the way bumping the burner up a little at the same time.
This exchange has me wondering about how airflow affects development during the dry and ramp. I would generally run 50%+ air through the drum for the entire roast rather than just at crack through finish. I feel like this provides the ability to increase the RoR while not missing out on the extra development that a longer dry&ramp without drum airflow affords, but then creating a sweeter cup by decreasing the ramp time especially. My test cases are few but seem to my hypothesis so far. Thoughts?
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boar_d_laze
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#2: Post by boar_d_laze »

cimarronEric wrote:I would generally run 50%+ air through the drum for the entire roast rather than just at crack through finish. I feel like this provides the ability to increase the RoR while not missing out on the extra development that a longer dry&ramp without drum airflow affords, but then creating a sweeter cup by decreasing the ramp time especially.
I'm not sure if I really understand what you're trying to say or not. But if I do, you may be a little bass ackwards in terms of how you understand your controls.

Damper full drum -> slowest RoR for any given gas setting. Damper full tray -> fastest RoR.

Even though I'm using a 1lb sample roaster, and you're using a 3kg our situations are similar.

Here are some not quite identical examples of how to use damper and fan
:
During Drying, I used to go with the damper about 80/20 tray, fan at 33%, because that's the minimum amount of air through the roaster to maintain negative pressure with a "sweet spot" load; and because higher air accelerates moisture loss. However, I found it too difficult to keep the RoR as low as I usually want it for the Drying interval (at least 6min from Charge to 300F, but usually 6:30 - 7:00). Now, I almost always charge at 50/50, 50%.

I normally go through Ramp with 50/50 damper, and 50% fan. That much air during Ramp costs some gas, to keep the drum clear of smoke and chaff. But be careful, too much air through Drying and Ramp can dry out the beans and trade fruits for baking or even ashiness. Either way, not a good exchange.

In order to keep Development time under control, I anticipate 1stCs by at least 10F, drop the gas, and go 100/0 drum, 100% fan all the way through to Drop.

Wrapping It Up
If you're looking for sweeter roasts, you may want to experiment with slower Drying and Development intervals.

Rich
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sversimo
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#3: Post by sversimo »

Im not sure if you need to use the airflow or not in order to contoll your roaster, but from what I have learned from experience and professionals: keep it simple, keep the airflow constant.

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cimarronEric (original poster)
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#4: Post by cimarronEric (original poster) »

boar_d_laze wrote:Damper full drum -> slowest RoR for any given gas setting. Damper full tray -> fastest RoR.
This is my understanding too.

I probably didn't word my question well. How about:

Given same RoR through Dry and Ramp, does increased air flow increase bean development?
But be careful, too much air through Drying and Ramp can dry out the beans and trade fruits for baking or even ashiness.
leads me to think this may be true. So, rather than a 6 min dry with 50/50 50% air, would 5 min dry with 80drum/20 50% air have a similar effect on the development of the bean?

I think the basis of my question comes from the fast finish profile A Fast Finish Roast Profile and it's reliance on high airflow to avoid scorching/tipping. Is that high airflow also contributing to the development and the ultimate flavor in the cup?

I'm going roast the Teklu today with 3 different air profiles and will report back. I was just wondering if anybody has already tested same RoR profiles with different airflows?
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boar_d_laze
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#5: Post by boar_d_laze »

sversimo wrote:Im not sure if you need to use the airflow or not in order to contoll your roaster, but from what I have learned from experience and professionals: keep it simple, keep the airflow constant.
I suppose it could depend on the roaster itself; or maybe it's a particular style of roasting with which I'm unfamilair. But...

Which professionals keep airflow constant in typical, modern drum roasters (which allow for adjustment)? It would be nice if you could name some names. The heavyweights I know about, like Boot, Diedrich and Perry, to name just three, adjust airflow throughout the roast.

Rich
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#6: Post by boar_d_laze »

cimarronEric wrote:So, rather than a 6 min dry with 50/50 50% air, would 5 min dry with 80drum/20 50% air have a similar effect on the development of the bean?
No. When it comes to shaping the profile, time trumps air unless there's too much or too little air.
I think the basis of my question comes from the fast finish profile A Fast Finish Roast Profile and it's reliance on high airflow to avoid scorching/tipping. Is that high airflow also contributing to the development and the ultimate flavor in the cup?
Well, I usually run full drum and 100% fan through Development partly as a way of keeping a very clean cup (unless I want to "season" with a little smoke), partly as a way of slowing the momentum of the very fast Ramp RoR, and partly as a way of giving me some room with the gas to get really fine control over Development RoR.

Context, context, context. I'm usually stretching Development rather than going for a fast finish.

Try reading up on Diedrich's roasting style. You might be able to learn something from him. IIRC, Diedrich's typical control schema is 25/75 (drum/tray), 50/50, and 75/25 -- but Diedrich roasters are designed to be used that way. Ditto Boot, who goes more slowly but uses Diedrich's and Giesens.

There's really no way to know what works best for you without sacrificing a lot of good beans to Fah-Kuppen-Loyn, the goddess of roasting education.
I'm going roast the Teklu today with 3 different air profiles and will report back. I was just wondering if anybody has already tested same RoR profiles with different airflows?
Yes. I found that -- pardon the repetition -- time trumps air unless there's too much or too little air. But that's not a statistical projection based on thousands of roasts by hundreds of roaster. It's going to be interesting to hear your results.

When RoR is sensitive, I suggest whatever airflow allows the most flexibility to control the roast with the gas, because it's considerably more responsive.

Just remember to keep negative pressure in the drum. It never takes much in the way of airflow, but the more beans in the drum, the more airflow is necessary. If you haven't already done so, do some test runs of varying charges by heating the roaster up to mid Ramp temps, holding a flame up to the trier's hole, and observing if it gets "sucked" in. No need to use beans good enough to drink; use stale sweepings if you have them.

Rich
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another_jim
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#7: Post by another_jim »

cimarronEric wrote:This exchange has me wondering about how airflow affects development during the dry and ramp. I would generally run 50%+ air through the drum for the entire roast rather than just at crack through finish. I feel like this provides the ability to increase the RoR while not missing out on the extra development that a longer dry&ramp without drum airflow affords, but then creating a sweeter cup by decreasing the ramp time especially. My test cases are few but seem to my hypothesis so far. Thoughts?
I've compared slow/low air and fast/high air dry and first ramp roasts on the Quest. I found the longer roasts to be less sweet and have more umami/nut/cereal flavors. This works well on more muscular coffees like Kenyas, less well on the fruit driven ones like Sidamos. No sure if any of this applies to Diedrichs.
Jim Schulman

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boar_d_laze
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#8: Post by boar_d_laze »

another_jim wrote:I've compared slow/low air and fast/high air dry and first ramp roasts on the Quest... No sure if any of this applies to Diedrichs.
Jim,

How about same speed, different airflow? My experience is that as long as there's adequate airflow (and adequate doesn't mean huge), time of the Dry and Ramp intervals means more than airflow in terms of shaping taste characteristics.

Also, we're talking USRCs which are altogether different animals from Diedrichs or Quests in terms of controlling airflow. USRCs have a fan speed rheostat AND a drum/tray damper. FWIW, the 3kg roaster is more responsive to air than my little 1 pound machine because (so USRC tells me) it has proportionally less thermal mass.

Rich
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another_jim
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#9: Post by another_jim »

boar_d_laze wrote:How about same speed, different airflow?
That requires higher ETs for lower airflow roasts. Generally speaking, the difference is subtly more "roastiness" on the low flow roasts. Obviously low growns and naturals can char in high ET roasts, so for these I almost never use low air.
Jim Schulman

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TomC
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#10: Post by TomC »

boar_d_laze wrote: Ditto Boot, who goes more slowly but uses Diedrich's and Giesens.

Rich
He doesn't use Dietrich's. He uses either of his Giesen's mainly, or the 1 pound San Franciscans (one old with weak airflow, one new with good airflow), and he has open barrel Proasters.

And he only goes slowly on profiles that require a taming of acids to balance out otherwise unbalanced coffees, particularly ultra bright Kenyan's or geisha's that need to avoid tannic tea flavors that stand out in faster roasts too prominently.
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