Removing Grassiness in Burundi Muninya Hill Kayanza Original Profile

roasting

#1

Hi All,

I’m a new owner of the Ikawa at home and excited to explore this new hobby of coffee roasting. I’m working through the Burundi bag right now and like many of you, I’ve noticed this grassy taste using the original profile. Being a total newbie, I just thought I would get used to it. This is how this coffee is supposed to taste! But I then decided I really didn’t like it.

In Rao’s book, he suggested that for grassy flavors you should “moderately steepen the early roast curve.” So that’s what I did this morning, and the lo and behold the smell/taste of grass/vegetable is gone! (I couldn’t wait to drink the roast). :smile:

I’ve also gone overboard and placed thermocouples into the Ikawa and I’m using the Roastmaster app to track the bean and exhaust temperatures using the supported ThermoQ Bluetooth device. This setup is pretty cool (imo). Anyway, here’s a comparison of the Ikawa Original profile (dashed lines) and the modified profile. The -only- change I made to the Ikawa profile was the first Inlet temperature point from 212Celsius@44s to 275celsius@1:00 (kind of like the temperature spike in the Ikawa espresso profiles)

I actually wonder whether 275C is too high…next time I might dial it back to 250C and see if the grassiness comes back. This is really interesting to me — one change totally changed the taste of the coffee! Everything else in the roast is the same (for those looking at the ending of the graphs, both sessions ended at 6:01m. I just forgot to “end” the roast tracking in the roastmaster app so it continued tracking the temperature probes.)

Regards,
Jonah


#2

What kind of thermocouple have you used, and where have you placed them? Perhaps you could post a photograph of how they are set up, if that’s possible.


#3

Here’s my setup:

  • ThermaQ device for $219
  • 2 Very thin thermocouples for $15 each (Wire dia: 0.01", 0.024" with insulation)
  • Roastmaster iOS app $14 to record roasting sessions. Connection to ThermaQ device is through Bluetooth so no wires or computer required.
  • Heat resistant tape from amazon, the ones used for heating ducts.

I considered attaching the ThermaQ to the ikawa body itself using this magnet tripod head but was concerned about the heat generated by the ikawa and how that might affect the ThermaQ so I opted to attach it to the power cord instead using Velcro so that it’s away from the ikawa. I wound electrical tape around the power cord to hide the thermocouple wires and make the whole thing more presentable, less unwieldy, and transportable. I love the look of the Ikawa, so I wanted to preserve the elegance as much as possible.

You can use any K thermocouple that you want (e.g. phidgets). I chose the ones above as it was convenient and it follows Hoos’ recommendation that the thermocouple should be as thin as possible. I ended up putting the first one (”BT”) in the middle of the chamber, at the level of the beans when they’ve expanded. The wire actually touches the beans at this point and it’s stiff but flexible to withstand the bean movement. I figured as long as the probe position doesn’t move (the tape ensures that) then my profiling temperature readings will be consistent and will be comparable from one session to the next. The second thermocouple (“ET”) I put in the exit channel. Because the wire is very thin, this doesn’t impede air exhaust nor bean exit. In reading the Hoos’ blog piece at Ikawa, it appears that that probe in the Pro is actually called the exhaust probe, so it seems I don’t really need this second thermocouple. I’ll see what happens going forward. Like what some of you discussed in previous forum threads, I want to be able to roughly translate Ikawa pro profiles to Ikawa Home once I run out of Ikawa green beans in my world kit and I start buying green beans online (e.g. Sweet Maria’s) or locally.

Some pictures:

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#4

Hello all,

I’ve run out of Burundi beans so I wanted to summarize my experiments with this bean for future users who may want to take things further.

  1. Original Ikawa profile - Really good. At the beginning, the coffee tasted grassy and I set out to modify the profile to remove it (the topic of the original post above). However, I noticed that around day 5, that taste subsided and fell to the background. So in retrospect, maybe I didn’t have to modify the profile and just let the beans rest and develop further?

  2. Removing grassiness - Rao writes that this taste means “mildly underdeveloped” and his recommendation was to “moderately steepen the early roast curve.” - which is what I did above and it actually worked. This will be useful in future roasting scenarios. The flavor did change (maybe with more muted flavor? But still good). One thing I didn’t try was to reduce the steepness of the curve from 275C/1:00 to say 250C/1:00. Another Rao recommendation to address grassiness was to “ensure the development time ratio is greater than 20%.” I think that the original Ikawa profile was just a bit under that around 18%, so one experiment that could be done is to simply lengthen the profile by say 30s to see what that tastes like. I ran out of Burundi beans before I could do that “lengthening” experiment.

  3. Other Profiles I tried and my notes on them

Ikawa Espresso v1 - Aroma is sweet, acidic. Almost meaty, smells like barbecue? More body, But as it cools more bitter compared to original profile which makes sense.

Martha Etheo profile - Traditional taste of coffee, Darker taste without hint of origin, No acidity anymore
still taste the grapefruit (peel?)

Burundi Dark - Søren posted this profile I think. Less acidity. Muted mellow flavors. Not bitter. Nice.

All in all it was a good run for Burundi. First crack appears to happen around the 5:00 minute mark into the profile when bean temp (BT) is around 185C and exhaust temp (ET) at around 200-205C. Of course this is so dependent on thermocouple placement so it’s really only useful for my machine. However, what’s interesting is that the ET is consistent with where Ikawa said first crack should be—at 205-210C (see their blog post). Yellowing consistently starts at 150C as well, which also agrees with the Ikawa blog posts. So these visual/auditory milestones could be used without thermocouples. The drying phase ends at 150C and the Maillard reactions start when the beans turn yellow. If you hear first crack, then you know you’re at 205C.

Anyways, on to the next bean, which I think will be Brazil.

Regards,
Jonah


#5

The Marshal Etheo profile should be dropped/hit the cool button, 5-15s after hearing the first sound of crack which is generally in the 464-472F/240-244C area. You should smell an aroma, usually blueberry. If you smell it but wait and the aroma is gone, the flavor will be gone too. The mass loss should be in the 13-14% range.

Hope that helps.


#6

Hi Deven,

Ahh, thanks for that tip. I let the Marshal Etheo profile run almost the entire program. I think it went to 2nd crack and it was just burnt. My entire place was smoky :-):joy: I’ll try again next time.

Regards,
Jonah


#7

Generally, if you put a bit more heat in at the start you can develop the roast further.

I remember a few folks talking about grassiness with that bean/roast. Probably a bit light for some.

I find that very light roasts on the Ikawa can really “mature” over time. I had a Kenyan one time that jumped with acidity early on but a few weeks later had settled down.

I tend to leave roasts around a week before drinking these days.


#8

Yea 1week is normal for me too, but I start smelling them at 3-5days. I was testing out charge/spike temp variations on a WP Ethiopian and 3-4days really hit the sweet spot. But generally tend not to let the grassiness rest out, i just consider that roast a fail and try adding more heat by either increasing temp, ROR of profile or lowering fan later in the roast.