Roasting to a) relative points or b) absolute points

Simon

Heya guys! Just had a curiosity...

I'm relatively new to monitoring temps while roasting (for many years just roasting on the 'fly', time-based), but was wondering something.

In terms of consistent roast depths, is it better to roast to:

a) a relative temperature point based on when first crack occurs/ends

Or

b) absolute temperature point (just ending when the beans hit a certain temperature)

Am not sure if what I'm saying makes sense, but I recently did a few roasts, the first two roasts FC happened pretty much the same temps. The third roast it was slightly different measurements..

Eg If in roast:

1) FC happened at 205, rolling was 212, end of FC was 220, and I pulled the roast at 224

2) FC happened at 211, rolling was 215, end of FC was 223

As the numbers are slightly higher, in order to get a consistent roast depth, would it be better to end that second roast at the exact same temp (224), OR end it relative to the end of FC in that first roast (about 4 degrees past the end of FC) which would be 227 degrees?

I hope this made sense haha.. thanks guys


(And obviously the profile ie how it got there matters, but I mean if I keep the same profile. These two profiles are attached too just for more info. The probe position was the same in both, and ambient temps were the same)

mycuppa

Grasshopper. Time matters not at the stages you are focusing upon......the final. A journey to 1st crack is more important than what happens afterwards and those 2 curves ar indeed very different. The more energy you get into the beans before setting your roast up to enter 1st. crack the more predictable or consistent your temp and crack events will be......assuming the same coffee. You really need to think in terms of degrees C added from first crack and not time, but while keeping a close eye on your declining rate of rise. If you crack is happening later or late, then it’s telling you the ramp up was too slow and flat. Time means nothing.......it’s what the curves are doing and the reactions upon coffee. The answer to your question is both A and B.

Simon

on 1540109013:

Grasshopper. Time matters not at the stages you are focusing upon......the final. A journey to 1st crack is more important than what happens afterwards and those 2 curves ar indeed very different. The more energy you get into the beans before setting your roast up to enter 1st. crack the more predictable or consistent your temp and crack events will be......assuming the same coffee. You really need to think in terms of degrees C added from first crack and not time, but while keeping a close eye on your declining rate of rise. If you crack is happening later or late, then it’s telling you the ramp up was too slow and flat. Time means nothing.......it’s what the curves are doing and the reactions upon coffee. The answer to your question is both A and B.

Hmm fascinating, thanks heaps for that! Yeah so previously I was going time-based but nowadays am not, so all good there! Am only new to the temps. I'm roasting on a Behmor 1600 (with the plus model board installed for extra manual controls). It's bizarre though, for these roasts I used the exact same roast profiles and same bean weight (even ambient temp was the same). Have no idea why the curves are different then... I used just the P1 auto profile (which is actually just full bawl heat right from the get-go), then at rolling first crack I changed to manual controls, dropping the heat output to 50% and doubling the drum rotation speed. Ah right so both relative and absolute number are important... but do you moreso think focus on the degrees C added from first crack? So in other words to get a more consistent roast depth, to keep the difference (end temp minus FC/end FC) in temperature between first crack and when I drop the roast the same (rather than just reach say 220 degrees C)? And obviously the curve matters greatly, but I feel I'm not at that stage yet and trying to focus on keeping a profile consistent (the auto profiles on Behmor, for the ramp-up anyway), altering it manually from rolling FC, and dropping at certain temps/depths to see what flavours develop. Very insightful thoughts by the way it is mightily appreciated (of course feel free to not give away your trade secrets, would understand haha ;D )

Koffee_Kosmo

Coffee has a finite temperature crack point First Crack starts at 195 to 210 deg Celsius ( depends on hardness of the beans ) Depending on the profile you want to use, the ideal is to reach the crack temperature at a set time In my own experience most of the flavour is developed in the length of time to first crack And my preferred profile is longer than the norm @ around 12 min to first crack But that’s the beauty of roasting as you are in control of what recipe you like So the answer to the question is that both, work hand in hand KK

Simon

on 1540606162:

Coffee has a finite temperature crack point First Crack starts at 195 to 210 deg Celsius ( depends on hardness of the beans ) Depending on the profile you want to use, the ideal is to reach the crack temperature at a set time In my own experience most of the flavour is developed in the length of time to first crack And my preferred profile is longer than the norm @ around 12 min to first crack But that’s the beauty of roasting as you are in control of what recipe you like So the answer to the question is that both, work hand in hand KK

Thanks heaps KK, very helpful . So I guess focusing moreso on what happens in the lead up to FC is more important. Have tried the first roast out and it actually tastes really good! Really stoked with that. So I think the next time I roast this bean I'll try to maybe get that curve looking a bit smoother. Not sure how though... I'm even thinking of doing my roast completely manually. I used the auto P1 profile until rolling FC last time (which is full heat anyway), but I may just use manual 100% and see what happens (you can set the heat to 0%, 25%, 50%, 75%, or 100%) I guess I'm still a little puzzled as to if a roast comes out with different temps, at what point to stop it to get it consistent, but I think it may be beside the point. If something had changed at the end point (eg what temp FC/end FC occurs)/, then the focus should be what happened in the LEADUP to FC, as obviously something had changed. And I only just realised that for that second roast, I forgot to put in the chaff tray. I didn't think much of it to begin with.. but it's possible it affected airflow a bit inside the roaster.. there ya go!

Koffee_Kosmo

From first crack to second crack is what I call the Coffee method stage If you use a brew style device then you stop the roast before second crack However if you drink espresso style then it’s best to take the roast to the golden triangle of 1) Just on second crack ( light roast ) 2) On second crack      ( med roast ) or past second crack    ( dark roast ) Second crack also has a temperature point at around 118 to 222 deg Celsius The answer to your chaff tray is probably a volume change Larger volume means the heat element works harder KK

Simon

on 1540611563:

From first crack to second crack is what I call the Coffee method stage If you use a brew style device then you stop the roast before second crack However if you drink espresso style then it’s best to take the roast to the golden triangle of 1) Just on second crack ( light roast ) 2) On second crack      ( med roast ) or past second crack    ( dark roast ) Second crack also has a temperature point at around 118 to 222 deg Celsius The answer to your chaff tray is probably a volume change Larger volume means the heat element works harder KK

Ah yep, I've found many people take their roasts to just on second crack, but I've never really had a great roast from it, and it would always be just a tad too dark. Even with this roasting lot, my first roast I took to the very first snaps of SC (profile not shown), just to get a good reference point at which temp it occurs for my setup. They had a few oil spots on them, and the taste was ok, but not really suited to the bean, or didn't really suit my taste. I found the second roast I did (the first profile shown) really nice and had alot more dimension, complexity and flavour to it (this is for espresso that is). Yet for others it seemed that ending the roast on the first snaps of SC got them alot of these characteristics. Which ia why it's great to hear from other experienced roasters that what works for your setup, your conditions, your beans, location etc is what matters! So I've learned that for my particular setup, ending the roast a bit before SC always got me really delicious roasts. Now that I've got temp measurements I can really focus on how to best reach that point. And I've also learned that even temperatures measured can differ from roaster to different roaster (eg my measured temp for when SC occurred was 229° Celsius, which I'm certain was not actual bean temperature anyway), so finding my own consistency of measurement will be what's important. Learning lots!

LeroyC

Hey mate. Love your threads Simon. Hehe. Time - it matters, but it’s the thing you check AFTER everything else, not the thing you use to guide yourself to your destination. So, end time should be within a certain range that you’ve determined to be acceptable for that particular roast. Chaff tray - in the Behmor it will DEFINITELY make a difference. There’s such a small amount of thermal mass and space in a Behmor that removing something as big as the chaff tray will definitely influence the roast. Don’t forget that as good as the manual controls are on the 1600 Plus it’s still not particularly responsive so you have to plan ahead even more than you would on a commercial roaster. Keep it up mate. Good stuff.

Simon

on 1540703504:

Hey mate. Love your threads Simon. Hehe. Time - it matters, but it’s the thing you check AFTER everything else, not the thing you use to guide yourself to your destination. So, end time should be within a certain range that you’ve determined to be acceptable for that particular roast. Chaff tray - in the Behmor it will DEFINITELY make a difference. There’s such a small amount of thermal mass and space in a Behmor that removing something as big as the chaff tray will definitely influence the roast. Don’t forget that as good as the manual controls are on the 1600 Plus it’s still not particularly responsive so you have to plan ahead even more than you would on a commercial roaster. Keep it up mate. Good stuff.

Haha glad you like em Leroy ;D Great, thanks for that mate. Yeah after years of roasting on the fly thought it was time to see what all the fuss is about with measuring temps and playing with the graphs . Yeah I figure I won't worry too much about time. I'll find a roast I like, see when it ended and make a note of it anyway, but won't really shoot too much for a particular time. A range sounds better. Even so, some of these roasts are in the 15-17 minute range so who knows what I'm even aiming for. Will let taste guide the way. Yeah makes sense regarding the tray.. it's a big hunk of metal! Will play around with the manual controls I think. I just think anything less than 100% heat input will be too slow a roast, so will start most roasts on 100% manual up until FC/rolling FC from now on, and won't worry about the auto modes. Knowing whether to reduce heat during the ramp up to FC is something absolutely beyond me haha (as to when to do that), so I might just keep an eye on the graph and go from there. Just a matter of getting that curve a bit smoother with no glitchy drops and tapering off better... but even so, I loved the second roast of these I did, so will play around with it. Thanks for the advice and encouragement, really appreciate it [emoji106]

LeroyC

on 1540706790:

Haha glad you like em Leroy ;D Great, thanks for that mate. Yeah after years of roasting on the fly thought it was time to see what all the fuss is about with measuring temps and playing with the graphs . Yeah I figure I won't worry too much about time. I'll find a roast I like, see when it ended and make a note of it anyway, but won't really shoot too much for a particular time. A range sounds better. Even so, some of these roasts are in the 15-17 minute range so who knows what I'm even aiming for. Will let taste guide the way. Yeah makes sense regarding the tray.. it's a big hunk of metal! Will play around with the manual controls I think. I just think anything less than 100% heat input will be too slow a roast, so will start most roasts on 100% manual up until FC/rolling FC from now on, and won't worry about the auto modes. Knowing whether to reduce heat during the ramp up to FC is something absolutely beyond me haha (as to when to do that), so I might just keep an eye on the graph and go from there. Just a matter of getting that curve a bit smoother with no glitchy drops and tapering off better... but even so, I loved the second roast of these I did, so will play around with it. Thanks for the advice and encouragement, really appreciate it [emoji106]

I wouldn’t worry about trying to get the curve smoother. I think you’ll find that little flat spot halfway up each curve has been when the fan has kicked in. While you obviously don’t want your roast to stall you said yourself that you couldn’t quite get the probe right in the middle of the bean mass so it’s probably exposed to changes in the environmental conditions and the bean temp will actually still be rising through that point. At work last week we did a little trial to try to improve our second darkest roast profile. We usually stop at 223deg which is usually around the 14:30 mark. We did a standard roast like this, but then we also did one that stopped at 222deg, but was given less heat through from first crack and ended at 15:00. It’s a balancing act as you obviously don’t want the roast to stall and/or bake. We just tasted them yesterday and there’s a noticeable difference that we’re pretty sure will be due to both the different end temp and drawn out post 1C development. So in this instance time was important, but as a product of the other variables.

Simon

on 1540933392:

I wouldn’t worry about trying to get the curve smoother. I think you’ll find that little flat spot halfway up each curve has been when the fan has kicked in. While you obviously don’t want your roast to stall you said yourself that you couldn’t quite get the probe right in the middle of the bean mass so it’s probably exposed to changes in the environmental conditions and the bean temp will actually still be rising through that point. At work last week we did a little trial to try to improve our second darkest roast profile. We usually stop at 223deg which is usually around the 14:30 mark. We did a standard roast like this, but then we also did one that stopped at 222deg, but was given less heat through from first crack and ended at 15:00. It’s a balancing act as you obviously don’t want the roast to stall and/or bake. We just tasted them yesterday and there’s a noticeable difference that we’re pretty sure will be due to both the different end temp and drawn out post 1C development. So in this instance time was important, but as a product of the other variables.

Yeah that must be it, the little dip didn't make sense but if a fan starts up that'd be it, thanks! I wonder if there's a spot in the drum that the fan doesn't hit where I can put the probe.. but doesn't matter. I'll focus just on making sure the roast doesn't stall. Ah that's interesting, especially as there was a noticeable taste difference! Yeah I'm not sure what effects things like that have on a roast. Eg if at rolling FC instead of 50% heat I did 25% and extend out when I hit the same temp, may just be a matter of experimenting. Cheers mate!