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CK
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Posted on 12/24/2023 8:47 PM
This profile is turning out some great results... For the past few months, I've changed my style to replicate roasts similar to this curve and the results have been surprisingly good... no more vegetal or sour flavors from roasts that are too short or too fast. An interesting observation is that despite the longer dry and maillard phases, the acidity of Ethiopian naturals is still very present if dropped with low development time. On my roast color meter, they generally range from 80-110 on the Agtron gourmet scale and all are very good, either as espresso or as a filter brew.
CK attached the following image:
p05_test_profile.jpg
 
oldgrumpus
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Posted on 12/24/2023 11:08 PM
I'd like to try that with my Ethiopian. Since I'm roasting with a drum, it'll be interesting to see if I can come to the same conclusion. Thanks for posting!
Clever Coffee Dripper
Grinder: Macap M4
Roaster: Completed drum roaster project photos shown here:
Photos https://goo.gl/ph...Da6K4wfqw5
Videos https://www.youtu...Bd1NrdpSUH
Build thread https://homeroast...post_38189
 
renatoa
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Posted on 12/25/2023 7:39 AM
CK, so you start with really cold machine, no preheat ?
 
oldgrumpus
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Posted on 12/25/2023 9:20 AM
It would look something like this. The red line indicates the charge but that line would join the profile.
oldgrumpus attached the following image:
f5c48c48-bf92-42cc-a421-bc7e645f0bce.jpeg
Clever Coffee Dripper
Grinder: Macap M4
Roaster: Completed drum roaster project photos shown here:
Photos https://goo.gl/ph...Da6K4wfqw5
Videos https://www.youtu...Bd1NrdpSUH
Build thread https://homeroast...post_38189
 
CK
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Posted on 12/25/2023 11:20 AM
This curve shows the temperature as seen from the beans perspective; they enter at room temperature of 23C and make their milestones from there. Every machine has different characteristics for charge temperature and probe readings so it’s easier to show from the starting point… if the milestones are met similarly, the start of the curve should be similar. I like how FransG does it by putting the bean probe in the FZ94 machine after charging. This shows the beans actual temperature rise without a turn point as seen in this post.
https://kostverlo...y-end.html
 
renatoa
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Posted on 12/25/2023 11:35 AM
Dang... great minds !
Already thinking to a mini trier like mechanism for this purpose... Grin
 
Yasu
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Posted on 12/26/2023 10:51 PM
I plotted the temperature.
I think it is a pretty good curve.
I turned it into a formula with an approximate curve, so I was able to put this formula into Artisan's device to display the target line, which I will copy next time.

Substituting time t for x, we get
BT and ROR target values at that time.
Yasu attached the following images:
2023-12-27_141536.png 2023-12-27_145543.png 2023-12-27_145456.png
Edited by Yasu on 12/27/2023 12:00 AM
 
renatoa
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Posted on 12/27/2023 1:51 AM
You can read more about the the formula of BT in the "Well tempered..." thread, it's the heat absorption of a body immersed in an environment with different temperature.

BT = AT + (ET-AT) * (1 - EXP(-t/k)))

where t is time, in seconds, and k is a constant specific to machine/beans/anything else.
You can try for start with a k value of 0.0032. If using 245 as value for ET, and 25 for AT, the curve you get is attached below.
DE typical value of 150C is at 4:20, and FC (200C) at minute 8.

Playing with various ET will give you virtual roasts shorter or longer.
You can use this tool for plotting the graph: https://www.symbo...calculator
~~~
renatoa attached the following image:
image_2023-12-27_094520982.png
 
Yasu
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Posted on 12/27/2023 3:00 AM
Renatoa.
Thank you for the instruction.

Since you mentioned that BT will be a function of ET, so we will control ET.
I just tried to display the target value of BT before that in Artisan for ROR and BT when ROR is reduced by a certain amount, as RAO said, so I will see if I can't have Artisan calculate ET once to make this BT and display that too.
Thank you very much.

However, I am still able to manage roasting with heater + burner while watching BT and ROR.
 
renatoa
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Posted on 12/27/2023 3:59 AM
Forgot to mention, that formula is for roasters using mainly hot air as heat transfer method.
Will not apply for radiant roasters, where ET is colder even than the beans !

RoR reduction comes natural, without any change, for this model. You can see this if plotting in the same graph the derivative of the profile curve.
All you have to do is to maintain firm ET until the neighborhood of the exothermal phase, about one minute before FC.
Obviously, this formula don't cover the FC flick and crash, no information about beans releasing steam.
 
Yasu
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Posted on 12/27/2023 5:31 AM
Thank you very much.
I put the formula you gave me into the Artisan device and also wrote a target curve for ET. For now, I will try to use about K=0.0030 based on past data.
I am looking forward to the next roasting.
Yasu attached the following images:
2023-12-27_202216.png 2023-12-27_202124.png
 
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