Confused about BT during crack - Page 3

Discuss roast levels and profiles for espresso, equipment for roasting coffee.
Bunkmil

#21: Post by Bunkmil »

Almico wrote:It's not, but what Scott refers to when he says "the first 2 minutes of data are not useful", he is talking about commercial roasters where the TP typically occurs around 1:20-1:30. So "the first 2 minutes includes the TP plus tiny bit after. If you TP is occurring at 30s, then the first 1 minute is not useful. By the time the BT has climbed 1/4 to 1/3 of the way to dry, the data is reliable under normal circumstances.

High initial RoR temps appear to produce divots in darker roasts. I also find the sag from a high initial RoR spike does not do my roasts any favors. Once I learned how to get a nice downturn and straight declining RoR, my coffee improved exponentially.

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Take that same graph where your TP is happening at 1:18@161F and plot a TP at 0:45@130F instead (just an example) and you will see that your ROR will have a much higher peak. It only tells you that your probe/system reacts differently. It doesn't mean that the roast is any different.

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Almico

#22: Post by Almico » replying to Bunkmil »

But if I was turning around at 0:45, and my peak RoR was 55*/min, I would either soak, use a lower heat setting or charge at a lower temperature so I didn't go over 45*/min.

Bunkmil

#23: Post by Bunkmil » replying to Almico »

That wouldn't make sense IMHO. Let's put it that way:

You have an excellent roast profile for a given bean. On that profile your TP is happening at 1:18@161F.
Now you change your probes on your roaster. Your new ones are more reactive. The exact same roast profile is now giving you a TP of 0:45@130F. Hence a higher ROR peak.
You would change your roast profile just because now you have a higher ROR peak ? I wouldn't change anything.

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Almico

#24: Post by Almico »

Bunkmil wrote:That wouldn't make sense IMHO. Let's put it that way:

You have an excellent roast profile for a given bean. On that profile your TP is happening at 1:18@161F.
Now you change your probes on your roaster. Your new ones are more reactive. The exact same roast profile is now giving you a TP of 0:45@130F.
You would change your roast profile just because now you have a higher ROR peak ? I wouldn't change anything.
I have changed probes from 5mm, to 3mm and then 2mm and back again. I have never found that drastic a difference, regardless of what Scott and Rob claim. That just hasn't been my experience.

I just had an 3mm RTD (slow) crap out and switched my rig on the fly from a vinthub and tmp-1200 back to 1048 with a 2mm TC. Using all the same heat and air settings, my profiles all followed my templates pretty much verbatim.

Bunkmil

#25: Post by Bunkmil »

I use 1.5mm probes on my Quest and my TP always happen at about 45s into the roast. My charge temp has little effect on that if any.

Let's not forget what TP is. It's only the time it takes for your probe to catch up with the real bean temperature. Your beans are not at 400F when you charge them. They are at room temperature.

Let's say that the beans are at 70F when you put them in the roaster.

A : Your TP is at 1:18@161F. That means that it took 1:18 for your beans to go from 70F to 161F. That's an average of 70F/min.

B : Your TP at 0:45@130F. That means that it took 45s for the beans to go from 70F to 130F. That's an average of 60F/min.

But the B ROR peak might still be higher than A because the TP is happening faster.

baldheadracing
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#26: Post by baldheadracing »

Almico wrote:I have changed probes from 5mm, to 3mm and then 2mm and back again. I have never found that drastic a difference, regardless of what Scott and Rob claim. That just hasn't been my experience.

I just had an 3mm RTD (slow) crap out and switched my rig on the fly from a vinthub and tmp-1200 back to 1048 with a 2mm TC. Using all the same heat and air settings, my profiles all followed my templates pretty much verbatim.
Just a thought - I notice almost a minute difference in TP between 5mm and 2mm probes on my 1kg roaster. One thing that both the factory 5mm and my 2mm probes share are steps to thermally isolate the probe from the heavy cast-iron faceplate of my roaster. Perhaps if your probe lengths are short/straight and mounted metal-to-metal to the heavy faceplate that I have seen in Turkish roasters, then that might explain why you see minimal changes where others see bigger changes ...

Nothing wrong with different data, it is all in how one uses it.
What I'm interested in is my worst espresso being fantastic - James Hoffmann

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Almico

#27: Post by Almico » replying to baldheadracing »

No doubt. My BT probe is mounted with a teflon compression fitting and sticks about 3" into the drum.