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iRoast - 4 Roast Profiles Thermocouple Results

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Discussions > Coffee > Home Roast > iRoast - 4 Roast...

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Haijin
Senior Member

Joined: 26 Dec 2004
Posts: 25
Location: Japan
Expertise: I love coffee

Espresso: Silvia PID
Grinder: Macap M5
Drip: Press Pot
Roaster: iRoast

Posted Tue May 31, 2005, 5:43pm Subject: iRoast - 4 Roast Profiles Thermocouple Results

Hi, I've been trying to suss out my new iRoast. Take a look at these graphs and photos, if you're interested: click here there are four roasts. i found that voltage plays a significant role. i'm wondering about what might make for a better roast profile with SM Monkey Blend or SM Liquid Amber - as I'm hoping to get some good roasts using those blends. Any suggestions for improving, especially roasts 2 and 4? Thanks.

jim_schulman
Senior Member

Joined: 19 Dec 2001
Posts: 3,772
Location: Chicago
Expertise: I live coffee

Posted Wed Jun 1, 2005, 2:16am Subject: Re: iRoast - 4 Roast Profiles Thermocouple Results

Haijin Said: Any suggestions for improving, especially roasts 2 and 4? Thanks. Posted May 31, 2005 link Yes. One simple, one more technical. The simple one: You are probably roasting too dark. At 470F, you are likely to get a lot of ashy tastes, epecially from the Brazils and monsooned malabars in the sweet maria's blends. If you hate acidity, and like roast tastes, try stopping at 455F to 460F. I'm referring to your bean probe, which gives readings fairly consistent with other air-roasters, whereas the I-roast readout, and it's programmed temperature, are not consistent machine to machine. The technical one: you want the beans to be dried out and an even colored yellow before getting above about 300F on the bean probe. This usually takes 3.5 to 5 minutes. Your roasts are starting a lot faster, and the beans will enter the first crack very unevenly developed. In order to even them out, you need to go excessively dark. The secret of a good roast profile below the first crack's end is very simple -- the best roast is the fastest roast which keeps the beans at an even color throughout. Above the first crack, you may want to slow down for lighter roasts, so the tastes develop. I like to spend about 2 to 4 minutes between the end of the first and the end of the roast, no matter how light or dark I'm roasting. I thnk you are roasting about 2 minutes too fast between 250F and 300F, and about a minute too slow between 300F and 390F. Finally, the 6 to 7 minutes roasting time after the first crack might as well be accompanied with a funeral march for the beans, you really need to pick up the pace here. How this tranlates to a program for your I-roast, I can't say.

Jim Schulman www.coffeecuppers.com

Haijin
Senior Member

Joined: 26 Dec 2004
Posts: 25
Location: Japan
Expertise: I love coffee

Espresso: Silvia PID
Grinder: Macap M5
Drip: Press Pot
Roaster: iRoast

Posted Fri Jun 3, 2005, 9:52am Subject: Re: iRoast - 4 Roast Profiles Thermocouple Results

Jim, Thanks for your help in pointing me in the right direction. I've been wondering about the beginning of the roast. The lowest setting on the iRoast is 320F. Using a setting of 325F, Roast 4, for instance, gets to 300F in 2 minutes (120grams). 150grams (Roast 5) gets to 300F in about 3 minutes. The only way to further lengthen the time may be to lower the voltage. Roast 4 I've now added roasts 5 (a ruined roast, due to the iRoast's inability to circulate Monkey Blend with its low speed fan setting), and roast 6 and roast 7, long roasts with slower ramps, and final end temps (likely funereal, but useful for learning, tasting). Some experts suggest stretching out the time between first and second crack, with slow ramps--maybe gone too long there. I'll apply your profile suggestions to my next roasts. Two questions: With first crack - using complex blends, I'm getting a first crack that can last up to several minutes, start to end - usually 1.5min.-2min. If the beans are brought up slowly to 300F, but I pick it up after that, first crack should be shorter and more definitive--a good thing? And, what might be a general maximum time for 455F-460F espresso blends, do you think? Richard

jim_schulman
Senior Member

Joined: 19 Dec 2001
Posts: 3,772
Location: Chicago
Expertise: I live coffee

Posted Fri Jun 3, 2005, 1:56pm Subject: Re: iRoast - 4 Roast Profiles Thermocouple Results

These readings make no sense, your TC reading s are way low. 1st crack usually starts at 385F to 400F, and the 2nd at 400F to 445F. Is the position the same as in the first roast; was the bean agitation and flow the same. It looks like there may be a problem in this department, since the roasts look very uneven.

Jim Schulman www.coffeecuppers.com

Haijin
Senior Member

Joined: 26 Dec 2004
Posts: 25
Location: Japan
Expertise: I love coffee

Espresso: Silvia PID
Grinder: Macap M5
Drip: Press Pot
Roaster: iRoast

Posted Fri Jun 3, 2005, 8:02pm Subject: Re: iRoast - 4 Roast Profiles Thermocouple Results

Yes, I see what you mean, I hadn't focused on that FC temp variation, not knowing it couldn't be right! The TC on my earlier roasts read 1st crack completely differently (more accurately). I'll recallibrate and reposition the TC and try a couple of new roasts today, with some hopefully better profiles. I cupped from roast 6 today - almost zero crema, no body, bright, a bit baked in the aftertaste (10 min. later an unpleasant aftertaste on the tongue akin to lime & clay). Some fruity hints too. A speculation: The iRoast has three main fan speeds, with exact setpoint changes, e.g. a 385F temp setpoint works completely differently than 390F: at 385F, the fan funs at high speed, a lot of bean circulation; at 390F the fan runs at medium speed, slowing circulation. Roast 5-7 were done with the first two stages below 390F (roast 7 with a long first stage of 380F) -- my TC is possibly reading the faster bean circulation/airflow as a lower temperature. My earlier roasts (1-4) were at 390F Stage 2 (starting at 5 minutes), this creates a steeper temperature ramp, as well. I hope to post up some better roast results today or tomorrow. Thanks again for your advice. I'm getting there . . .

Haijin
Senior Member

Joined: 26 Dec 2004
Posts: 25
Location: Japan
Expertise: I love coffee

Espresso: Silvia PID
Grinder: Macap M5
Drip: Press Pot
Roaster: iRoast

Posted Sat Jun 4, 2005, 4:48am Subject: Re: iRoast - 4 Roast Profiles Thermocouple Results

Jim, I ran a Roast 8, a first attempt to approximate your advice. unfortunately I can't lengthen the iRoast drying stage past 3.5 minutes, maybe that's enough though. Also I can shorten the 300F-390F time still further, and lengthen the final stage a bit as well, if desired. The results look a lot better than previous roasts 1-7! What do you think of the roast 8 results, any thoughts? I wrote up your advice, and made a visual chart as well. It's a bit simplistic. Take a look here. Hope you don't mind -- if I've made any errors please let me know and I'll correct them -- extremely valuable information, thanks. PS My TC seems to be working okay now, tested it at 212F and against internal callibration, it reads about 2F high. Richard

jim_schulman
Senior Member

Joined: 19 Dec 2001
Posts: 3,772
Location: Chicago
Expertise: I live coffee

Posted Sat Jun 4, 2005, 10:13am Subject: Re: iRoast - 4 Roast Profiles Thermocouple Results

Hi Richard, Make the roast finish 4 to 5 minutes from when the 1st crack starts -- if you get a very odd bean or blend, there may be no gap between the end of the first and start of the second crack. The roast profile looks good and the beans have come out even colored and not charred, so it seems a better roast than the previous ones. Of course, the proof will be in the cup. Many I-roasts apparently have problems with the chaff collector when roasting dry processed (chaffy) beans. This can lead to poor agitation when the fan runs in its low gear. There is a page up at Sweet Maria's detailing Tom's attempts to work around the problem. It may help you, since you reported bean circulation problems.

Jim Schulman www.coffeecuppers.com

Haijin
Senior Member

Joined: 26 Dec 2004
Posts: 25
Location: Japan
Expertise: I love coffee

Espresso: Silvia PID
Grinder: Macap M5
Drip: Press Pot
Roaster: iRoast

Posted Sat Jun 4, 2005, 7:37pm
Subject: Re: iRoast - 4 Roast Profiles Thermocouple Results

jim_schulman Said:

Make the roast finish 4 to 5 minutes from when the 1st crack starts -- if you get a very odd bean or blend, there may be no gap between the end of the first and start of the second crack.

Posted June 4, 2005 link

I'll be cupping Roast 8 tomorrow, I think with more pleasure than my previous attempts. Thanks for clarifying the end-roast time, above - I'll apply it to my next roasts.

The roast profile looks good and the beans have come out even colored and not charred, so it seems a better roast than the previous ones. Of course, the proof will be in the cup.

It's a lot more even, isn't it, no charring or divots either. Looking forward to testing the result...

Many I-roasts apparently have problems with the chaff collector when roasting dry processed (chaffy) beans. This can lead to poor agitation when the fan runs in its low gear. There is a page up at Sweet Maria's detailing Tom's attempts to work around the problem. It may help you, since you reported bean circulation problems.

I have a similar problem - looks like Tom hasn't found a good solution yet... I'm finding that in the end-roast stage by raising the voltage a bit, I can use a setpoint of perhaps as low as 380F-390F (I was a bit too fast at 390F, Roast 8). At these setpoints, the fan is at medium-to-high speed, aiding circulation.

Thanks for your help, many points of confusion resolved,
Richard (Kumamoto, Japan)

jim_schulman
Senior Member

Joined: 19 Dec 2001
Posts: 3,772
Location: Chicago
Expertise: I live coffee

Posted Sat Jun 4, 2005, 11:07pm Subject: Re: iRoast - 4 Roast Profiles Thermocouple Results

Glad to help. With your level of engagement and care, you'll be teaching me in a few months.

Jim Schulman www.coffeecuppers.com

Haijin
Senior Member

Joined: 26 Dec 2004
Posts: 25
Location: Japan
Expertise: I love coffee

Espresso: Silvia PID
Grinder: Macap M5
Drip: Press Pot
Roaster: iRoast

Posted Sun Jun 5, 2005, 6:25am Subject: Re: iRoast - 4 Roast Profiles Thermocouple Results

Glad to help. With your level of engagement and care, you'll be teaching me in a few months. Ha ha, as if! Coffee is a wonderful combination of mystery, science and art isn't it. Relating to coffee, within the patient care and attention is an aroma at a distance.

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