First, an apology and warning that perfectly fine light roasted coffee will be harmed in this post.

Not being a fan of light roasts - but having a couple batches of light roasted coffee, was an opportunity to see what I could do with it...

By exploiting the Ikawa's ability to ramp temperatures really-really fast, I experimented with re-roasting a light roast with a brief exposure to FC-SC temperatures, a full day after the initial roast:

Two minutes was just enough time for the bean-mass temp readings to reach equilibrium with the empty chamber temperature:



Three minutes allowed the beans to track the empty-chamber temperature for over a minute:



This is how the color changed:



One interesting observation: the same thermal ramp at the end of a complete roast starting from greens would yield a full roast-level darker result. So it appears I can't stop a roast and finish it later. Perhaps some chemical reactions get locked in once the initial roast cools. Not really feeling like my dreams have been smashed over this.

I'll post tasting results later, but I admit to a visual bias for roast color that likely slants my tasting notes, and I haven't mastered preparing espressos blindfolded. I anticipate the term "baked" may come into play, although that word makes me think about a yummy batch of brownies. I think the term 'baked' means all the tasty volatiles have been driven out, leading to a watered-down brew - did I get that right?

I also learned some new things about how the Ikawa Home handles full-scale temperature ramps: It seems to pause very briefly at about 165C chamber temperature, slows the ramp rate roughly in half, and reaches the target temperature in about 30 seconds without any overshoot - nice. I speculate the pause at 165C might be due to some internal power dissipation limits in the heat exchanger kicking in. Ikawa's engineers might wince at these sorts of thermal excursions, so you might want to think twice before trying this yourself. Counting on there not being a hidden self-destruct sequence in their firmware/software...

Peppersass wrote:Here's a link to the Ikawa Pro Espresso 1 profile that I started with.

If you'd like a copy of my edited version, PM me your email address and I'll send it to you.

Thank you! I was able to view in the Pro app, at which point I discovered it has 8 temperature setpoints and 11 fan setpoints!




I can wing it, but I'd like to hear any suggestions for how to reduce to 6 temperature points and 5 fan points. Is your edited version as pointilicious?

Also noteworthy is how gentle the ramp is - actually curves in the opposite direction compared to the curve for a steadily-declining RoR - cool.

Cwilli62 wrote: Yeah, I'm signed in. On the Android app. Does it matter that I don't have the roaster in my possession yet? I was trying to get comfortable with how to use the app and share profiles/recipes before the roaster arrives.

I think it does, as the app will check (and insist) that you have the appropriate model, so it may not fully register with the recipe-sharing servers.

I also suggest you don't update the app, as the current version still allows profile editing - the next version may hold editing hostage for $34/month.

Iowa_Boy wrote:I keep studying that roast curve in post #76.
I think I understand why the inlet temperature spikes in the first 30-45 seconds.
If I am thinking through this correctly, the exhaust temp drops initially after charging since the beans are absorbing heat.
Since it's a closed loop system, that drop in exhaust is compensated by a rise in inlet temperature.
Once there is equilibrium, the inlet curve and exhaust curve follow the same basic trajectory. So at that point building a home profile from the pro one is easier.

Theoretical question:
How big a deal is it to build in that early inlet temp spike on a home profile?
It will be interesting to test how quickly the exhaust temp recovers without it. How long does it delay drying phase?
Seems like by trying to emulate the closed system with the spike, it might be too easy to get scorching if the spike is too high.
I know Ikawa has it built into many of their home profiles, but I wonder if preheating, charging, and skipping the spike may work best.
Will try to test that out tomorrow, as well as try to figure out the delta between inlet and exhaust temp early and late in roast.

Yeah, some weird 'stuff' going on there. The Home will halt if you try to drop the greens after it starts - whereas the Pro actually does the opposite? Also, the Home version preheats to around 45C chamber temp before starting the profile, whereas post #76 shows it preheating to 130C before the beans are dropped in - that's such a big differential it's not surprising the control loop would freak out for a while. Dropping cold beans into a hot chamber seems like some sort of homage to drum roasters, IMHO.

I've read that temperatures below 150C don't really influence the roast outcome, so does it matter how straight or wiggly it is? Also, what's the rush - I don't understand the hurry to get through the drying phase - it's already much faster than a drum roaster. I've read the goal is to simply dry out the beans - but not too dry, as apparently some amount of water is still needed for the browning phase.

I think the red curve (in the Pro app) is the inlet temperature, and the originating source of heat for any point downstream. So, from a causality perspective it should always lead the chamber temperature (orange curve?) measured by the upper probe. The control loop has to respect that causality, usually by slowing down the response time. That said, the upper temp shows an excursion that appears (to me at least) to violate several laws of physics in that first 60 seconds - could just be a math problem in the software.

Question for the Pro owners:
Do your machines cap the maximum rate of change in temperature? I suspect that might be an artifact of the long delay in the control loop that would be upset by sudden impulses (like dropping cold beans into the chamber). See post #67 in this thread, where an earlier model Home (50g) overrode a programmed 30 second ramp into a 60 second ramp. The new Ikawa Home (100g) has no software/firmware limit on temperature ramps - and I'm having a lot of fun with that, but I'd like to post profiles that will work on any machine.

Iowa_Boy wrote:How big a deal is it to build in that early inlet temp spike on a home profile?

Check out post #23 in this thread: Ikawa Home thermal performance

GDM528 wrote:Thank you! I was able to view in the Pro app, at which point I discovered it has 8 temperature setpoints and 11 fan setpoints!

image


I can wing it, but I'd like to hear any suggestions for how to reduce to 6 temperature points and 5 fan points. Is your edited version as pointilicious?

Also noteworthy is how gentle the ramp is - actually curves in the opposite direction compared to the curve for a steadily-declining RoR - cool.

I was thinking of leaving the fan settings at the default for the Home profile. It seems like most of the home profile have similar fan settings, so to keep it simple would just leave as is.

In terms of the temperature points, I looked at the ROR graph, and it seems like you can safely eliminate the 3:38 point and the 9:35 one.
I looked at a bunch of the other Pro profiles, and a lot of them have declining ROR. So still not quite sure how this doesn't bake the coffee, but perhaps that is discussion for another time.

Here is what I was thinking of trying - everything is time shifted by 1 minute due to preheat.
Time Exhaust Temp (F)
0 0
1:00 266 (Charge beans at 1:00 - corresponds to preheat on Pro)
2:39 288
6:07 349
8:29 402
9:49 417
11:09 422

Of course, those temps are exhaust temps, so need to convert to inlet temps.
Was going to run a test batch of 75 g beans to see if I can estimate the difference in inlet vs exhaust temp at different time points.
Should then be a decent approximation of Espresso profile 1!
Thoughts?

As an aside, the Tim Wendleboe and Rob Hoos profiles look pretty good and easy to replicate. Rob Hoos one seems quite simple with temp points corresponding to dry end and first crack. TW profile is much faster, and probably works best for light roasts. Seems like having the two of those on the Home would be quite versatile.

GDM528 wrote:I think the red curve (in the Pro app) is the inlet temperature, and the originating source of heat for any point downstream. So, from a causality perspective it should always lead the chamber temperature (orange curve?) measured by the upper probe. The control loop has to respect that causality, usually by slowing down the response time. That said, the upper temp shows an excursion that appears (to me at least) to violate several laws of physics in that first 60 seconds - could just be a math problem in the software.

Calling myself out for being stupid:
The red curve in the Pro app is NOT the inlet temperature. The red curve is the upper/chamber/exhaust temperature - an amalgam of inlet temperature, bean temperature, and structural temperature. That's why it's below the orange curve of the inlet temperature. Laws of physics and causality are sated. whew

Still noteworthy how the inlet temperature jumps after the beans are dropped. Not clear why that's considered a good thing...

So I tested my exhaust probe out, and well, it seems to work really well.
Great placement, doesn't interfere with anything.
Next thing I did was test my roaster empty and with 75 grams of beans.
I was trying to figure out the offset for inlet temp vs exhaust temp.
It's an inexact science, but 90 degree difference seemed pretty close.
So I created a profile using that information.

Here is my Home profile based on Ikawa Pro Espresso roast 1:
Time Temp (F)
1:00 356 (Charge beans at 1:00 so everything is shifted 1 minute)
2:39 378
6:07 439
8:29 492
9:49 507
11:09 514

Artisan curve is below for an Ethiopian Natural
Overall, I think ROR appears similar to the Pro ROR for this profile. Mostly flat.
Roast looks very even, no signs of scorching, but proof will be in the tasting!
I would so far call this a success.
On to test two other Ikawa Pro Profiles!

Ikawa Rob Hoos Profile to Home Version

Time Temp (F)
1:00 302 (Charge beans at 1:00)
4:06 388
8:35 490
10:30 500

Artisan Graph below.
Enough testing for this weekend, will look forward to tasting!
Would like to find a profile that is faster, but so far quite happy that both the Espresso Profile 1 and Rob Hoos profiles worked well with a natural bean.