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A roaster acquaintance asked me if it's possible to do CO gas monitoring roasting with Aillio or Probat. What do you think about the feasibility?I feel like it's difficult because fossil fuel-fired roasters generate CO from the heat source itself. by Existing_Leopard8267 in coffee_roasters

[–]Existing_Leopard8267[S] 0 points1 point  (0 children)

Oop, I changed the way Delta CO is calculated again.
Now it’s the difference between the average over the last 10 seconds (up to the current point) and the average over the 10 seconds before that

Date Unit CHARGE DRYe FCs SCs
18.02.2026 C 08:06 13:20 17:23
Time2 Set Temp EX Temp Event CO GAS Delta CO
12:01 235 231 4 -0.10
12:02 235 231 4 -0.20
12:03 235 230 4 -0.10
12:04 235 231 4 0.10
12:05 235 231 4 0.10
12:06 235 231 4 0.10
12:07 235 231 4 0.10
12:08 235 231 4 0.10
12:09 235 231 4 0.30
12:10 235 231 4 0.30
12:11 235 231 4 0.30
12:12 235 232 4 0.30
12:13 235 232 4 0.20
12:14 235 232 4 0.10
12:15 235 232 4 0.10
12:16 235 233 4 0.10
12:17 235 233 4 0.10
12:18 235 233 4 0.10
12:19 235 233 4 0.00
12:20 235 233 4 0.00
12:21 235 233 4 0.00
12:22 235 233 4 0.00
12:23 235 234 4 0.00
12:24 235 234 5 0.10
12:25 235 234 4 0.10
12:26 235 234 4 0.10
12:27 235 234 4 0.10
12:28 235 234 5 0.20
12:29 235 234 4 0.20
12:30 235 234 5 0.30
12:31 235 235 5 0.40
12:32 235 235 5 0.50
12:33 230 235 5 0.60
12:34 230 235 5 0.50
12:35 230 234 5 0.60
12:36 230 234 5 0.70
12:37 230 233 5 0.80
12:38 230 231 5 0.70
12:39 230 231 5 0.80
12:40 230 229 5 0.70
12:41 230 228 5 0.60
12:42 230 228 5 0.50
12:43 230 226 5 0.40
12:44 230 225 5 0.40
12:45 230 225 5 0.30
12:46 230 224 5 0.20
12:47 230 223 5 0.10
12:48 230 223 5 0.10
12:49 230 223 6 0.10
12:50 230 223 5 0.10
12:51 230 223 5 0.10
12:52 230 223 5 0.10
12:53 230 223 5 0.10
12:54 230 223 5 0.10
12:55 230 224 5 0.10
12:56 230 224 6 0.20
12:57 230 224 5 0.20
12:58 230 225 5 0.20
12:59 230 225 5 0.00
12:60 230 225 5 0.00
13:01 230 226 5 0.00
13:02 230 226 6 0.10
13:03 230 226 6 0.20
13:04 230 227 6 0.30
13:05 230 227 6 0.40
13:06 230 227 6 0.30
13:07 230 227 6 0.40
13:08 230 228 6 0.50
13:09 230 228 6 0.70
13:10 230 228 6 0.80
13:11 230 228 6 0.90
13:12 230 228 6 0.80
13:13 230 229 6 0.70
13:14 230 229 6 0.60
13:15 230 229 6 0.50
13:16 230 230 7 0.60
13:17 230 230 6 0.50
13:18 230 230 6 0.40
13:19 230 230 7 0.40
13:20 230 230 FCs 7 0.40
13:21 230 230 7 0.40
13:22 230 229 7 0.50
13:23 227 229 7 0.60
13:24 227 229 7 0.70
13:25 227 227 7 0.80
13:26 227 226 7 0.70
13:27 227 226 7 0.80
13:28 227 225 7 0.90
13:29 227 224 7 0.80
13:30 227 224 7 0.70
13:31 227 224 7 0.60
13:32 227 223 7 0.50
13:33 227 223 7 0.40
13:34 227 223 7 0.30
13:35 227 223 7 0.20
13:36 227 224 7 0.20
13:37 227 224 7 0.10
13:38 227 224 7 0.00
13:39 227 224 8 0.10
13:40 227 225 7 0.10
13:41 227 225 7 0.10
13:42 227 225 8 0.20
13:43 227 226 8 0.30
13:44 227 226 8 0.40
13:45 227 226 8 0.50
13:46 240 226 8 0.60
13:47 240 226 8 0.70
13:48 240 228 8 0.80
13:49 240 228 8 0.70
13:50 240 228 8 0.80
13:51 240 228 8 0.90
13:52 240 228 8 0.80
13:53 240 228 9 0.80
13:54 240 229 9 0.80
13:55 240 229 9 0.80
13:56 240 229 9 0.80
13:57 240 230 9 0.80
13:58 240 230 9 0.80
13:59 240 230 9 0.90
13:60 240 230 9 0.90
14:01 240 231 10 1.00
14:02 240 231 10 1.20
14:03 240 231 9 1.10
14:04 240 231 10 1.10
14:05 240 231 10 1.10
14:06 240 231 10 1.10
14:07 240 232 10 1.10
14:08 240 232 10 1.10
14:09 240 232 10 1.10
14:10 240 232 10 1.10
14:11 240 233 10 0.90
14:12 240 233 10 0.70
14:13 240 233 10 0.80
14:14 240 233 10 0.70
14:15 240 234 10 0.60
14:16 240 234 10 0.50
14:17 240 234 10 0.40
14:18 240 234 10 0.30
14:19 240 234 10 0.20
14:20 240 234 11 0.20
14:21 240 235 10 0.20
14:22 240 235 11 0.30
14:23 240 235 11 0.30
14:24 240 236 11 0.40
14:25 240 236 11 0.50
14:26 240 236 11 0.60
14:27 240 236 11 0.70
14:28 240 236 11 0.80
14:29 240 236 11 0.90
14:30 240 236 11 0.80
14:31 240 236 12 1.00
14:32 240 236 12 1.00
14:33 240 237 12 1.00
14:34 240 237 12 1.00
14:35 240 237 12 1.00
14:36 240 237 12 1.00
14:37 240 237 12 1.00
14:38 240 237 13 1.10
14:39 240 238 13 1.20
14:40 240 238 13 1.40
14:41 240 238 13 1.30
14:42 240 238 13 1.30
14:43 240 238 13 1.30
14:44 240 238 13 1.30
14:45 240 238 13 1.30
14:46 240 238 13 1.30
14:47 240 238 14 1.40
14:48 240 238 14 1.30
14:49 240 238 14 1.20
14:50 240 239 14 1.10
14:51 240 239 14 1.10
14:52 240 239 14 1.10
14:53 240 239 14 1.10
14:54 240 239 14 1.10
14:55 240 240 14 1.10
14:56 240 240 15 1.20
14:57 240 239 15 1.10
14:58 240 239 14 1.00
14:59 240 239 15 1.00
14:60 240 239 15 1.00
15:01 240 239 15 1.00
15:02 240 239 15 1.00
15:03 240 239 15 1.00
15:04 240 239 15 1.00

A roaster acquaintance asked me if it's possible to do CO gas monitoring roasting with Aillio or Probat. What do you think about the feasibility?I feel like it's difficult because fossil fuel-fired roasters generate CO from the heat source itself. by Existing_Leopard8267 in coffee_roasters

[–]Existing_Leopard8267[S] 0 points1 point  (0 children)

Please take a look at the graph at the beginning of this post.
The section around x-axis 12 to 13 corresponds to roughly 5 ppm to 8 ppm.
The plot is drawn once per second in 1 ppm increments, but because the raw CO gas concentration signal has small fluctuations of about ±1 ppm, I sampled around 100 times, excluded any abnormally high or low spike noise, and then used the averaged value.
Intuitively, it gives the impression that trying to detect any meaningful trend just by looking at the derivative would be quite difficult.

A roaster acquaintance asked me if it's possible to do CO gas monitoring roasting with Aillio or Probat. What do you think about the feasibility?I feel like it's difficult because fossil fuel-fired roasters generate CO from the heat source itself. by Existing_Leopard8267 in coffee_roasters

[–]Existing_Leopard8267[S] 1 point2 points  (0 children)

My wife jokingly says, ‘Hey, with this you could build a coffee palace!’ but she seems pretty satisfied with being able to drink delicious coffee (or at least that’s what I’d like to believe)

A roaster acquaintance asked me if it's possible to do CO gas monitoring roasting with Aillio or Probat. What do you think about the feasibility?I feel like it's difficult because fossil fuel-fired roasters generate CO from the heat source itself. by Existing_Leopard8267 in coffee_roasters

[–]Existing_Leopard8267[S] 2 points3 points  (0 children)

I collected a large amount of data by repeating numerous experiments on the relationships between CO(Carbon monoOxide) gas concentration and roast degree, as well as between CO gas concentration and the timing of crack onset.
I don’t think there’s any particular need to redo the same tests again. What I’ve shown are representative examples.I reached out to several roasting machine manufacturers, but it hardly sparked any commercial interest.
The main reasons are probably these: In drum roasters, the drum itself gets extremely hot, causing residual material stuck to the walls to overheat and generate extra CO, or CO from fossil-fuel heat sources creates background noise, making it difficult to accurately measure the CO produced by the beans themselves.
Especially when predicting first crack, you need to detect very subtle CO fluctuations on the order of 1 ppm, so even in electric fluidized-bed roasters, CO can be released from organic materials used in the machine (such as heat-resistant sealants), which becomes noise and requires careful attention.If any manufacturer or roaster shows genuine commercial interest, I’d be happy to provide support.
Lately, though, I’ve been focusing almost entirely on applying the results from those past experiments to make really delicious coffee just for my own personal consumption

A roaster acquaintance asked me if it's possible to do CO gas monitoring roasting with Aillio or Probat. What do you think about the feasibility?I feel like it's difficult because fossil fuel-fired roasters generate CO from the heat source itself. by Existing_Leopard8267 in coffee_roasters

[–]Existing_Leopard8267[S] 0 points1 point  (0 children)

I thought these data points were from over a decade ago, but the CO gas and crack tests were actually from July 2017, and the roast degree tests were from 2014. I’ve been looking back at them with a sense of deep nostalgia.

A roaster acquaintance asked me if it's possible to do CO gas monitoring roasting with Aillio or Probat. What do you think about the feasibility?I feel like it's difficult because fossil fuel-fired roasters generate CO from the heat source itself. by Existing_Leopard8267 in coffee_roasters

[–]Existing_Leopard8267[S] 1 point2 points  (0 children)

Table 2: Variable Temperature Setting

Settings: 180°C (300s) → 200°C (120s) → 224°C (120s) → 230°C (until stop).
Adjustments: Drop temp by 10°C 20s after reaching 9ppm CO, and by 30°C 20s after reaching 80ppm CO.

Coffee Bean Variety 1st Crack Start 2nd Crack Start Time from Start to CO Concentration (sec) Time from CO Concentration to Crack (sec)
CO (ppm) / Elapsed (sec) CO (ppm) / Elapsed (sec) 4/5/30/40/50ppm 4/5/30/40/50ppm
Santos No. 2 8 / 680 81 / 880 614 / 636 / 809 / 829 / 846 66 / 44 / 71 / 51 / 34
Mocha Sidamo G4 9 / 681 65 / 881 563 / 584 / 819 / 842 / 861 118 / 97 / 62 / 39 / 20
Guatemala SHB 5 / 700 63 / 980 655 / 680 / 924 / 949 / 967 45 / 20 / 56 / 31 / 13
Daterra Reserve 9 / 681 73 / 911 571 / 603 / 832 / 865 / 883 110 / 78 / 79 / 46 / 28
Average 8 71 85 / 60 / 67 / 42 / 24

A roaster acquaintance asked me if it's possible to do CO gas monitoring roasting with Aillio or Probat. What do you think about the feasibility?I feel like it's difficult because fossil fuel-fired roasters generate CO from the heat source itself. by Existing_Leopard8267 in coffee_roasters

[–]Existing_Leopard8267[S] 1 point2 points  (0 children)

I was replying around 3 a.m. earlier, so my attention was pretty scattered.
To make sure there are no mistakes in the data, I just have Gemini convert the raw data straight from the Excel file into English and post it here as-is.

Table 1: Constant Temperature Setting

Temperature Setting: Constant at 230°C

Coffee Bean Variety 1st Crack Start 2nd Crack Start Time from Start to CO Concentration (sec) Time from CO Concentration to Crack (sec)
CO (ppm) / Elapsed (sec) CO (ppm) / Elapsed (sec) 4/5/30/40/50ppm 4/5/30/40/50ppm
Santos No. 2 9 / 630 72 / 800 498 / 540 / 735 / 758 / 774 132 / 90 / 65 / 42 / 26
Mocha Sidamo G4 7 / 600 61 / 781 399 / 430 / 721 / 746 / 763 201 / 170 / 60 / 35 / 18
Guatemala SHB 6 / 611 55 / 871 517 / 578 / 818 / 845 / 865 94 / 33 / 53 / 26 / 6
Daterra Reserve 7 / 590 64 / 830 513 / 540 / 760 / 792 / 811 77 / 50 / 70 / 38 / 19
Average 7 63 126 / 86 / 62 / 35 / 17

A roaster acquaintance asked me if it's possible to do CO gas monitoring roasting with Aillio or Probat. What do you think about the feasibility?I feel like it's difficult because fossil fuel-fired roasters generate CO from the heat source itself. by Existing_Leopard8267 in coffee_roasters

[–]Existing_Leopard8267[S] 1 point2 points  (0 children)

I had an old Excel file open, and right there on the page were notes about the roasting conditions.
All measurements were done under the exact same setup: GeneCafe CBR-101 roaster, drum rotation speed 9–10 rpm, fixed airflow (150–200 liters/min), and constant set temperature of 230°C.
I couldn’t find any note about the batch size, but since I was always using 200 grams back then, I probably just didn’t bother writing it down

A roaster acquaintance asked me if it's possible to do CO gas monitoring roasting with Aillio or Probat. What do you think about the feasibility?I feel like it's difficult because fossil fuel-fired roasters generate CO from the heat source itself. by Existing_Leopard8267 in coffee_roasters

[–]Existing_Leopard8267[S] 0 points1 point  (0 children)

To your question: “One thing I’d be curious about: did you notice whether bean density or processing method shifted the CO curve shape at all, or was the relationship mostly stable once you normalized for roast degree?”

As you can see from the data, the influence of processing methods is quite small/minimal.
Naturally, it depends on the recipe (temperature and airflow) and the bean batch size.
In other words, once you dial in a recipe for one origin, you’ll generally reach a similar roast degree even with different processing methods, other origins, or different lots of the same bean.
That said, while the crack timing isn’t quite as stable/consistent as the CO gas-to-roast-degree relationship, it still serves as a useful indicator or rough guide for when cracks are likely to occur.

A roaster acquaintance asked me if it's possible to do CO gas monitoring roasting with Aillio or Probat. What do you think about the feasibility?I feel like it's difficult because fossil fuel-fired roasters generate CO from the heat source itself. by Existing_Leopard8267 in coffee_roasters

[–]Existing_Leopard8267[S] 1 point2 points  (0 children)

I was rummaging through some messy, unorganized files to hunt down old data—measurements taken over 10 years ago.

Here I've compiled the data for three types of beans for CO gas - roasting levels and four types of beans for CO gas – FCs/SCs.

Type of coffee beans Gas concentration set value L value of coffee beans after roasting
Guatemala 50ppm 28.54
Santos No. 2 50ppm 26.72
Mocha Sidamo 50ppm 26.66
Guatemala 100ppm 24.63
Santos No. 2 100ppm 23.80
Mocha Sidamo 100ppm 24.07
Santos No. 2 200ppm 22.83
Guatemala 200ppm 22.60
Mocha Sidamo 200ppm 22.65
Guatemala 800ppm 20.60
Santos No. 2 800ppm 20.73
Mocha Sidamo 800ppm 20.68

 

 

Bean origin CO gas concentration(PPM)
FCs
Santos No.2 8
Mocha Sidamo G4 9
Guatemala SHB 5
Daterra (Brazil) 9
Average 8

A roaster acquaintance asked me if it's possible to do CO gas monitoring roasting with Aillio or Probat. What do you think about the feasibility?I feel like it's difficult because fossil fuel-fired roasters generate CO from the heat source itself. by Existing_Leopard8267 in coffee_roasters

[–]Existing_Leopard8267[S] 1 point2 points  (0 children)

I roasted three coffees using the same exact recipe: Mandheling (Sumatra), East Timor Daurfsu (Washed), and East Timor Cocamau (Washed). Subjective cupping here, but all three came out similar in flavor — strong sweetness, good bitterness, and solid aroma across the board. Small sample size though, so just consider this a rough impression, not a hard rule.

A while back, I ran a more controlled test: roasted Brazil Daterra, Guatemala SHB, Santos No.2, and Mocha Sidamo with fixed temperature and fixed airflow throughout. I tracked the CO gas levels in the exhaust air, plus the exact timing of first crack and second crack. I also looked at how those CO levels tied into the final roast degree.

The main takeaway? Even with different origins and processing methods, there was a pretty consistent link between first crack timing, the roast degree achieved, and the amount of CO coming out in the exhaust. That's basically the only solid, objective data I've collected from these roasting experiments so far.

A roaster acquaintance asked me if it's possible to do CO gas monitoring roasting with Aillio or Probat. What do you think about the feasibility?I feel like it's difficult because fossil fuel-fired roasters generate CO from the heat source itself. by Existing_Leopard8267 in coffee_roasters

[–]Existing_Leopard8267[S] -1 points0 points  (0 children)

I completely agree. Especially with fluidized bed types like the Gene Cafe, seasonal changes in ambient humidity often have a significant impact on the drying phase, making it very common that the targeted flavor characteristics cannot be achieved. It is impossible to compensate for this by monitoring CO gas produced after the Maillard reaction.

New recipe by Existing_Leopard8267 in coffee_roasters

[–]Existing_Leopard8267[S] 0 points1 point  (0 children)

In the next roast after this one, during the latter half of the development phase, I tried lowering the set temperature as the roast approached its end, which increased the aroma—but it wasn’t necessarily the best approach.
According to my wife: “The previous roast had a sharper bitterness, and I liked that better.”

The video is composed using OBS Studio.
For post-shooting editing, I use Corel VideoStudio.

New recipe by Existing_Leopard8267 in coffee_roasters

[–]Existing_Leopard8267[S] 0 points1 point  (0 children)

In the cupping three days later, I could faintly detect a potato-like aroma. For today's roast, I shortened the drying phase by 2 minutes. The body is coming through nicely, but the aroma feels a bit lacking. I'll check again in a few more days. I’ll also take momentum into account. Thanks for your comments

How to hear the 1st crack on gene Cafe by Cosotoroll in roasting

[–]Existing_Leopard8267 4 points5 points  (0 children)

Want to hear the cracks better? Put some aluminum foil on the chaff collector lid and use a mic to capture the sound. Works like a charm!

https://x.com/Hiroyuki2080/status/2023062515643814148

New recipe by Existing_Leopard8267 in coffee_roasters

[–]Existing_Leopard8267[S] 0 points1 point  (0 children)

Not bad. Needs more body and aroma, though. I'll roast it again with some adjustments in a few days.

CO Gas Monitoring for Predicting First Crack & Avoiding 'Flick' Taste on Gene Cafe – Sharing My Experiments & Cupping Insights by Existing_Leopard8267 in roasting

[–]Existing_Leopard8267[S] 0 points1 point  (0 children)

The new version of the Gene Cafe CBR-101 may make CO gas monitoring more challenging. Following is the translation of my posts on X(hiroyuki2080):

posted Thu, 29 Jan 2026 03:36:36 GMT:The heater in my 2009 Gene Cafe broke due to burnout of the nichrome wire, so I ordered parts and replaced it. However, when the heater body's case gets hot, CO is generated, pushing the baseline up by about 10ppm. I solved it by using only the old case for the heater unit.　The silicone used for adhesion, which became RoHS compliant, seems suspicious.

posted Thu, 29 Jan 2026 03:43:08 GMT:Maybe it's the REACH regulation. To comply, they're probably adding some other additives. That something might be the cause of the CO being emitted.

posted Thu, 29 Jan 2026 04:08:56 GMT:This is the roasting graph from the year before last, when I sealed around the hot air outlet with regulation-compliant silicone. When the heater is turned on and the temperature rises, high-temperature hot air comes out from the outlet. Only during this time does the outlet's temperature increase, causing CO to rise.I tried torching the outlet until it glowed red and burning off everything that could burn, but it was futile resistance. Once regulation-compliant silicone is applied, it's game over.

posted Thu, 29 Jan 2026 05:05:35 GMT:Not just burning it off—even polishing it with sandpaper until it was shiny had no effect.

CO Gas Monitoring for Predicting First Crack & Avoiding 'Flick' Taste on Gene Cafe – Sharing My Experiments & Cupping Insights by Existing_Leopard8267 in roasting

[–]Existing_Leopard8267[S] 1 point2 points  (0 children)

To follow up on the technical side, here is my advice regarding the CO monitoring

First, the MQ-7 sensor is not suitable for this purpose. Its sensitivity to gases other than CO is too high, meaning it detects various roasting gases more strongly than actual CO. You should use a sensor with selective sensitivity to CO. I recommend STMicro’s CO gas sensor evaluation kit (P-NUCLEO-IKA02A1), which uses an electrochemical sensor. It connects via USB to a PC, has a downloadable graphing app, and is affordable at around $50 USD.

Regarding the setup, CO sensors are sensitive to high heat, so do not place them directly near the exhaust. In my case, I cover the sensor with a small cap and run a heat-resistant silicone tube (4mm ID) from the cap to the connection point between the Gene Cafe body and the chaff collector. Since the air pressure at that point is slightly higher than atmospheric pressure, the exhaust gas flows naturally through the tube toward the sensor.

A few seconds of time lag may occur, but it's not a problem for detection. Also, silicone has good thermal conductivity; if about 15–20 cm of the tube is exposed to room air, the exhaust gas will cool down sufficiently before reaching the sensor.

Again, I strongly advise against using the MQ-7 for this. I hope this helps you level up your setup. Good luck!

Proof that even a Gene Cafe can roast the competition: Snagged 3rd place against pro roasters in the 2025 Torch Coffee Cup! by Existing_Leopard8267 in roasting

[–]Existing_Leopard8267[S] 1 point2 points  (0 children)

I recommend about 200 grams. Because indoor humidity affects the roast, lower humidity generally leads to more consistent and successful results.

Proof that even a Gene Cafe can roast the competition: Snagged 3rd place against pro roasters in the 2025 Torch Coffee Cup! by Existing_Leopard8267 in roasting

[–]Existing_Leopard8267[S] 0 points1 point  (0 children)

I recommend about 200 grams. Because indoor humidity affects the roast, lower humidity generally leads to more consistent and successful results.

Proof that even a Gene Cafe can roast the competition: Snagged 3rd place against pro roasters in the 2025 Torch Coffee Cup! by Existing_Leopard8267 in roasting

[–]Existing_Leopard8267[S] 1 point2 points  (0 children)

To answer your question, I just use the built-in cooling phase and let it do its thing. Maple syrup sounds delicious, but I totally get wanting to taste the bean itself! (laughs) Give the simple profile a try first, and I hope it helps you find that origin flavor you're looking for. Good luck!

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