Roasting ain't easy - not even for Marshall Hance - Page 4

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

#31: Post by rmongiovi »

If it's the max RoR of ET then why mark it on the BT line? And it isn't even the max RoR of ET. The max RoR of ET would have to be where the slope of the ET graph is steepest. And it appears to me that is also between 00:02 and 00:03.

The "money in the bank" arrow and the "Max. RoR" X are just the maximum ET.

Rao does this same thing in his book. He makes up a graph to "illustrate" a point and the graph is clearly manufactured and doesn't truly illustrate the point he's trying to make. Making up data isn't right regardless of whether it's a peer reviewed journal or a lecture on the principles of roasting.

mbenedet

#32: Post by mbenedet »

rmongiovi wrote:Rao does this same thing in his book. He makes up a graph to "illustrate" a point and the graph is clearly manufactured and doesn't truly illustrate the point he's trying to make. Making up data isn't right regardless of whether it's a peer reviewed journal or a lecture on the principles of roasting.
Which graphs were messed up in Rao's book?

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Almico
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#33: Post by Almico »

In reality, Max BT RoR likely occurs between 00:00 and 00:01.

My max ET RoR occurs when I kick the air on at DE.

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Before that I am roasting with low air (more conduction) and heat is being built up around the drum. When the airflow is increased at DE, the reserve hot air is sucked into the drum and the more convection part of the roast begins. I believe this is what she means my Max RoR. It's the ET RoR not BT.

rmongiovi

#34: Post by rmongiovi »

mbenedet wrote:Which graphs were messed up in Rao's book?
"messed up" is probably being overly harsh, but on page 46 he has a BT curve with a box in the center highlighted. This graph is labelled "This curve's highlighted section is the basis for 'Fragment A' and 'Fragment B' in the following two graphs." The highlighted section in that graph is clearly and smoothly concave down. But "Fragment B" is mildly concave up. He's making a "delta T" argument and that's fine. But the graphs are just made up to illustrate his point. My point was that it's clearly not really based on that supposedly real BT graph. Fragment A illustrates a supposedly larger delta-T and Fragment B illustrates a supposedly smaller delta-T but since they're completely manufactured they don't actually prove anything. He didn't really measure outer bean vs inner bean temperatures in situations that mirror those two graphs to show that those outer bean temperature curves really result in the corresponding inner bean temperature curves. I would rather have seen them labelled "this is my theory" than point them back to an apparently real BT curve to lend them artificial credence.
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edpiep

#35: Post by edpiep »

OldmatefromOZ wrote:As ususual with roasting it depends...
Im still learning every roast I cup and a lot depends what one is looking for in roasted coffee?

As others have mentioned the roasting system in use will always have its unique properties (temp measurements / placement) so it may need to be different.

The point is that particularly for small home roasters having some kind of MET / ET reading thats reliable and changes to it bring notable differences to a blind cupping is more useful than chasing perfect BT lines.
I agree with this Stephen (plus the other content I omitted). My awareness of the "ET" or MET lines in my case during roasting has really aided me having better control of my roasts and get closer to where I want them to be on the cupping table.

I think my question was answered in regards to maintaining a "steady" MET temp post DE. I have been getting better results with higher overall MET temps plus I'm able to change my approaches with more precision too. This last roast of a Nicaraguan I have is showing great promise considering it's an 84-85 point coffee, not huge complexity but sweet and butterscotchy (2 days off roast). My goal was to try and get to my max MET temp right around DE which meant I had to push more gas into the soak and also increase my max gas at TP so I could get a smoother last 2 minutes of the roast.

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I want to try what you did on your shared roast Alan and get more airflow into the middle phase so it will shorten. Hopefully this will allow more space for a DTR closer to 20% but still only have 13-13.5% weight loss.

OldmatefromOZ

#36: Post by OldmatefromOZ »

Excellent edpiep looks like you are making progress.

This is where I am currently.

BT probe is 3mm and more like an ET probe with the roaster empty, sits above drop door just off centre. When the drum is full (500g), because of how the vanes are set up it has a constant heavy stream of beans flowing over it, so a decent mix of ET / BT. I realised this means my Delta BT ROR needs to be a lot more horizontal looking. MET is a mix of exhaust temp and drum temp with a bare K type probe just touching the top lip INSIDE of the drum at the start of the exhaust.

Taken me awhile to work out the best temperature for good development without adding roasty notes while hitting the 6 - 8 min peak MET as suggested by Jim and holding it there, within 5C seems to be acceptable. After some less than perfect attempts worked out I needed to make adjustment to gas prior to the MET I want to peak at then just after to lock it in.

The peak MET is occurring right around where assumed caramelization is starting 170 - 175C, which may or may not be true / of interest.

Logging MET and gas settings separately on paper and have added all the info to the roast log after, anywho likely only relevant to me but may be of interest to others.

These roasts are presenting a crisp upfront sweetness that I have been chasing for some time which is promising. The first is a medium blend, 50% BPN / 30% Guat / 20% Indo for a traditional style espresso blend and the 2nd is Eth Yirg carbonic maceration natural for filter.

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CarefreeBuzzBuzz
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#37: Post by CarefreeBuzzBuzz »

This dialog has been a bit confusing to me probably because there was no baseline as to what was being measured other than bean temp.

MET stands for Maximum Environmental Temp in Artisan and is marked on the graph and shown as in Alan's graph. There is no peak MET, there is only one MET. For those that are not showing it on their graphs, look to Config>Events, bottom of the dialog box.

From what I understand, there is no standard as to what is being measured with the probe labeled ET, as the position of the thermocouple varies widely. On my roaster its the air within the drum, but on many it's the exhaust temp of the air and the position of that measurement varies.

So seems like some clarity around what is being measured is needed.

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CarefreeBuzzBuzz
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civ

#38: Post by civ »

Hello:
CarefreeBuzzBuzz wrote: MET stands for Maximum Environmental Temp ...
... no peak MET ...
Indeed ... =-)
There's ET and the highest point it reaches, MET.
CarefreeBuzzBuzz wrote: ... there is no standard as to what is being measured ...
Well ...
You do have a point.

In my case, others may opine differently, as an architect by trade I see environment as "that which surrounds" whatever we are referring to.

I don't think examples are needed but in the case that occupies our attention, I'd argue for defining environment (the 'E' in 'ET') as that which surrounds the beans inside the roasting chamber, be it a steel drum rotating over a heat source or a pyrex tube with hot air blown through it.

I don't think it ever crossed my mind that it could be anything else.
So to me, ET is the temperature actually surrounding the beans as they are being roasted.
Not too easy to measure ...

In my drum roaster I have probes for ET and BT but I also have an analog pizza oven thermometer measuring the temperature inside the roaster box but outside the drum just to have a reference of what is going on and see how these two temperatures relate as the roast progresses.

As your post implies, the problem with measuring ET (or anything temperature related in a coffee roaster) is how and where to measure it.

From my (limited) experience, I'd say that if you have a probe inside the drum but not touching the beans, you are the closest you will get to measuring ET (with these methods) and that if your probe measures exhaust temperature, what you are getting is more a reference to ET ie: the environmental temperature inside the drum.
Easier to measure but ...

This could well end up being the same value for both (or not), depending on how your roaster is designed/built. 8^7

Cheers,

CIV

edpiep

#39: Post by edpiep »

CarefreeBuzzBuzz wrote:This dialog has been a bit confusing to me probably because there was no baseline as to what was being measured other than bean temp.

MET stands for Maximum Environmental Temp in Artisan and is marked on the graph and shown as in Alan's graph. There is no peak MET, there is only one MET. For those that are not showing it on their graphs, look to Config>Events, bottom of the dialog box.

From what I understand, there is no standard as to what is being measured with the probe labeled ET, as the position of the thermocouple varies widely. On my roaster its the air within the drum, but on many it's the exhaust temp of the air and the position of that measurement varies.

So seems like some clarity around what is being measured is needed.

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Yeah, I am going to change the name of my currently labeled "MET" probe to "ET2" and change my current "ET" probe name to "ET1" or something. I will do some editing needless to say. I have always thought of MET as the "Measured Environment Temp" since I picked that name up from the old Huky Forum (maybe I have always had it mixed up and it should be like "Measured Exhaust Temp").

All Hukys come with 3 probes unless otherwise stipulated, BT and ET are really close to each other. The BT probe is in the bean mass that is always being pushed up and to the left leaving the ET probe, being to the right of the BT probe and slightly above it, exposed to only the air temp inside the drum. My "MET" probe is located outside the drum but INSIDE the external metal drum sheath and to the right of the exhaust intake. The Huky "MET" probe is basically the same thing as most everyone else's "ET" probe it seems. I just figured a lot of people knew about Huky probe placements (which if you do then I guess this hasn't been confusing???) and what all their labels signify. As you can see, the marker for "Maximum Environment Temp" on my ET line is more or less useless because it just measures a temp very close to that of BT at drop...which isn't helpful to me lol.

edpiep

#40: Post by edpiep »

OldmatefromOZ wrote:
This is where I am currently.
Also, thanks Stephen for sharing these images. I was watching some Mill City videos last night and seeing similar ET flatlines post DE and thought, "ok yeah, I have some more to work on." Now seeing yours as well just served to confirm my suspicion that I am going to alter my roasts plans once again *sigh*

Gonna need to get more practice greens :roll: