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Thread: Roasting to a) relative points or b) absolute points

  1. #1
    Senior Member simonsk8r's Avatar
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    Roasting to a) relative points or b) absolute points

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    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 I did two roasts:

    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)
    Last edited by simonsk8r; 21st October 2018 at 05:14 PM.

  2. #2
    Super Moderator Javaphile's Avatar
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    The entire profile matters. A change in any part of it will result in a different taste in the cup.


    Java "Everything is relative" phile
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    Mal Dimal's Avatar
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    Very true and quite amazing regarding how small a change can produce such a marked difference...
    It's why we all keep detailed records of all of our roast batches.

    Mal.

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    Senior Member simonsk8r's Avatar
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    Yeah true, good point! But in terms of ending the roast to get one consistent to the first, I'm just wondering if it's better to end at the same temp, or the temp relative to the end of FC (the same difference in temperature from end of FC).

    Well I guess it may be a matter of just tasting each roast and seeing how it compares in the cup ay .

    Even though I ended that second roast at pretty much the same temp (224 for the first, 223 for the second), it definitely seems to have a different colour depth and weight loss in the first was 16.71%, the second one was 16%.

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    Senior Member Yelta's Avatar
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    Quote Originally Posted by simonsk8r View Post
    Yeah true, good point! But in terms of ending the roast to get one consistent to the first, I'm just wondering if it's better to end at the same temp, or the temp relative to the end of FC (the same difference in temperature from end of FC).

    Well I guess it may be a matter of just tasting each roast and seeing how it compares in the cup ay .

    Even though I ended that second roast at pretty much the same temp (224 for the first, 223 for the second), it definitely seems to have a different colour depth and weight loss in the first was 16.71%, the second one was 16%.
    G'Day Simon, I don't use profiling software, did so early in my roasting career (about 10 years ago) however found it added a layer of complexity I didn't want or need.

    FWIW I only monitor temp and time, I aim for first crack @ 14 mins, it almost always occurs right on 200°C, my next target is approx 225°C @ 19 mins, my roasts are even and consistent, have yet to have a dud, although naturally some are better than others, overall very happy with my results.

    As far as your moisture variation is concerned, I assume you were roasting from the same batch of beans each time?

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    Senior Member solace's Avatar
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    When I roast I aim to end at the same temp for the same profile however I ensure I arrive at that temp in the same manner as the ‘template’ profile: i.e. always reach FC at the same time and temp (though time I allow for some slight wiggle room) then end the roast at the same temp after FC (219C)

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    Senior Member simonsk8r's Avatar
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    Quote Originally Posted by Yelta View Post
    G'Day Simon, I don't use profiling software, did so early in my roasting career (about 10 years ago) however found it added a layer of complexity I didn't want or need.

    FWIW I only monitor temp and time, I aim for first crack @ 14 mins, it almost always occurs right on 200°C, my next target is approx 225°C @ 19 mins, my roasts are even and consistent, have yet to have a dud, although naturally some are better than others, overall very happy with my results.

    As far as your moisture variation is concerned, I assume you were roasting from the same batch of beans each time?
    Awesome Yelta, I like your approach! Thanks for that!

    Yeah I want to keep it as simple as possible. So you're a fan of end temp as being a good guide/goal (but also FC occurring in a certain time)... awesome I'll play around with that for sure.

    And yep exactly the same bean and batch weights. But the first batch I dropped at 224 whereas the second was 223, so that may account for the 0.67% difference hehe.

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    Senior Member simonsk8r's Avatar
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    Quote Originally Posted by solace View Post
    When I roast I aim to end at the same temp for the same profile however I ensure I arrive at that temp in the same manner as the ‘template’ profile: i.e. always reach FC at the same time and temp (though time I allow for some slight wiggle room) then end the roast at the same temp after FC (219C)
    That's great, cheers for that!

    Yeah I'm yet to play around with the template profile (I'm assuming that essentially is uploading the old profile that was a great result over it and then as you go with the new roast trying to replicate that curve yeah?), as I need a good profile I'm happy with first, but great to know you approach it with end temp in mind, yet ensure the profile curve is as close as possible to the other.

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    Senior Member solace's Avatar
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    Quote Originally Posted by simonsk8r View Post
    (I'm assuming that essentially is uploading the old profile that was a great result over it and then as you go with the new roast trying to replicate that curve yeah?)
    Spot on!

    Once you find that ideal profile then it really is as simple as keeping your batch weight the same and making some slight variations to your charge temp to account for variables such as ambient temp, humidity, wind sheer (joking - unless you roast outside, that might actually be a variable to consider then!). I find that first minute(ish) of the roast is the most crucial, if you get to turning point at the same time and temp then the rest should fall into place nicely.

    Enjoy the experimentation!
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  10. #10
    Senior Member simonsk8r's Avatar
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    Quote Originally Posted by solace View Post
    Spot on!

    Once you find that ideal profile then it really is as simple as keeping your batch weight the same and making some slight variations to your charge temp to account for variables such as ambient temp, humidity, wind sheer (joking - unless you roast outside, that might actually be a variable to consider then!). I find that first minute(ish) of the roast is the most crucial, if you get to turning point at the same time and temp then the rest should fall into place nicely.

    Enjoy the experimentation!
    Awesome, great to know, thanks for that.

    Ah yep I roast outside nowadays haha so wind shear may be a factor hehe.

    Am pretty sure on the Heatsnob roast monitor you just click load template and then start roast from there. But yeah gotta nail roasts with this new approach first hehe.

    I'd love to just go full manual with the Behmor, but wouldn't really know what I'm doing, so have been going with P1, then manual when I hit rolling FC.

    So I may start with just with doing more roasts, ending it at a set temp (try a few different end temps), if I like how it tastes at that depth, try to replicate, but experiment with HOW I get there next time to see how it affects taste (which I have not much clue where to start with that, but will research)

    Appreciate it

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    Mal Dimal's Avatar
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    Time and Temperature are sort of 'incidental' to be honest.
    I find that much better consistency of outcomes results when controlling the roast via the Rate of Thermal Energy Input - Rate of Rise, etc
    This can be linked to temperature events that you're trying to achieve or maintain and thereafter, time sort of looks after itself...

    Mal.
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    Senior Member simonsk8r's Avatar
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    Quote Originally Posted by Dimal View Post
    Time and Temperature are sort of 'incidental' to be honest.
    I find that much better consistency of outcomes results when controlling the roast via the Rate of Thermal Energy Input - Rate of Rise, etc
    This can be linked to temperature events that you're trying to achieve or maintain and thereafter, time sort of looks after itself...

    Mal.
    Ah I see what you mean... fascinating. I have a feeling I may be tinkering more and more with the manual controls hehe. And adjusting heat on the fly perhaps...

    Yeah I figured time wouldn't need to be so much of a focus... just heat input as the main variable to control, and all else are things which happen on the side (but give valuable info).

    I don't yet know what I'm trying to achieve yet, but seeing alot of people's profiles having that 'big steep increase to tapering off' curve seems to be popular

  13. #13
    Mal Dimal's Avatar
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    Just suck it and see plus keep good records including taste results, post-roast.
    There's heaps of great info here on CS plus loads more from various places around the world which can be found via the Web and of course, plenty of written reference material, often referred to in these threads.

    Most importantly though, is what you do yourself with your equipment in your location using your own roast batch records.

    Mal.
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    Senior Member solace's Avatar
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    Quote Originally Posted by Dimal View Post
    Most importantly though, is what you do yourself with your equipment in your location using your own roast batch records.
    This!

    It took me a a while to realise that not all roaster’s are created equal (have even seen that moving a roaster to a new building in the same city causes it to behave quite differently) and each individuals grey matter process events quite differently! Using reference material from other roasters is most helpful when used as a measure against your own data.
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    Senior Member simonsk8r's Avatar
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    Quote Originally Posted by Dimal View Post
    Just suck it and see plus keep good records including taste results, post-roast.
    There's heaps of great info here on CS plus loads more from various places around the world which can be found via the Web and of course, plenty of written reference material, often referred to in these threads.

    Most importantly though, is what you do yourself with your equipment in your location using your own roast batch records.

    Mal.


    Quote Originally Posted by solace View Post
    This!

    It took me a a while to realise that not all roaster’s are created equal (have even seen that moving a roaster to a new building in the same city causes it to behave quite differently) and each individuals grey matter process events quite differently! Using reference material from other roasters is most helpful when used as a measure against your own data.
    Awesome, yep am quite a record-taker so that'll help for sure, and yeah I'm realising that it has to be what works for me, my setup, roaster, data etc.

    Thanks heaps guys

  16. #16
    Senior Member simonsk8r's Avatar
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    I'm also confused why those two profile curves look quite different to each other, when I used exactly the same beans, weight, profile etc.

    I might even try to switch to fully manual on my Behmor from the start and see how that goes. P1 auto profile I also thought would result in a much quicker roast... unless perhaps something needs fixin'!

  17. #17
    Senior Member solace's Avatar
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    I assume your first pic is your initial batch of the day and the second is a subsequent batch? If so then the variation in curves looks the result of thermal energy being retained in the system (for the subsequent roast). You can counter that with manual adjustments during your subsequent roasts.
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    Senior Member noonar's Avatar
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    That's a very bumpy ROR "curve" simonsk8r (especially the top graph), I would be worried about a leak somewhere in my system if I had such a bumpy curve. Do you know why it's happening to you?

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    Senior Member simonsk8r's Avatar
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    Quote Originally Posted by solace View Post
    I assume your first pic is your initial batch of the day and the second is a subsequent batch? If so then the variation in curves looks the result of thermal energy being retained in the system (for the subsequent roast). You can counter that with manual adjustments during your subsequent roasts.
    Yeah, actually the first pic is the second roast of the day, the next one is the third.

    Ah I see, or would be better to just wait longer in between roasts to let everything cool down? Ambient temp was the exact same inside the roaster for both roasts, but perhaps other things weren't quite cooled down yet...? (I think there was maybe 20-30mins between roasts, including the full cooling cycle on the Behmor)

    Don't quite think I have the hang of making manual adjustments.. although I can give that a go

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    Senior Member simonsk8r's Avatar
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    Quote Originally Posted by noonar View Post
    That's a very bumpy ROR "curve" simonsk8r (especially the top graph), I would be worried about a leak somewhere in my system if I had such a bumpy curve. Do you know why it's happening to you?
    Ah really... nah I have absolutely no idea what happened there. It's my first time with the probe in the middle of the roasting drum (just recently did the mod), so am very new to roasting with temps. Do you reckon there's a leak of sorts? :s

    I did roast outside, can wind gusts do that? Hehe

  21. #21
    Senior Member Yelta's Avatar
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    Quote Originally Posted by simonsk8r View Post
    Ah really... nah I have absolutely no idea what happened there. It's my first time with the probe in the middle of the roasting drum (just recently did the mod), so am very new to roasting with temps. Do you reckon there's a leak of sorts? :s

    I did roast outside, can wind gusts do that? Hehe
    Weather conditions can have quite an affect, my heat input varies markedly from summer to winter, after a few years working with the same setup you get to know the intricacies pretty well.

    BTW, roasting in full manual mode would be a great teacher, once again, all about getting familiar with the process at it's basic level.
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  22. #22
    Senior Member simonsk8r's Avatar
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    Quote Originally Posted by Yelta View Post
    Weather conditions can have quite an affect, my heat input varies markedly from summer to winter, after a few years working with the same setup you get to know the intricacies pretty well.

    BTW, roasting in full manual mode would be a great teacher, once again, all about getting familiar with the process at it's basic level.
    Cheers Yelta, yeah I've always noticed ambient temperature having an effect, but the day I roasted was a little windy so perhaps something happened there...

    Yeah I'm actually trying to start completely fresh with roasting now that I've got my mod set up, I'll of course remember everything I've learned that was of use, but want to start fresh in terms of approach and learning.

    The Behmor manual modes are essentially 0%, 25%, 50%, 75% or 100% heat application, and double drum speed option, so I'll just try those exclusively for my next roasts. Really unsure what happened with those roasts.. but will see if any other funny stuff happens on manual mode...

    Cheers

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    Senior Member solace's Avatar
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    Quote Originally Posted by simonsk8r View Post
    Ah I see, or would be better to just wait longer in between roasts to let everything cool down?
    This is where I need to step aside and let someone else provide the advice. I have zero experience with Behmor. I assume the manufacturer states a cooling cycle is required after each roast batch?

    My home roaster (KKTO) and commercial roaster I use from time to time don’t utilise cooling cycles between batches, this means that for each consecutive batch the system is retaining more thermal energy and thus requires less aggression for each consecutive batch - this sort of thermal retention is my best friend when it comes to the systems I use.
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  24. #24
    Senior Member simonsk8r's Avatar
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    Quote Originally Posted by solace View Post
    This is where I need to step aside and let someone else provide the advice. I have zero experience with Behmor. I assume the manufacturer states a cooling cycle is required after each roast batch?

    My home roaster (KKTO) and commercial roaster I use from time to time don’t utilise cooling cycles between batches, this means that for each consecutive batch the system is retaining more thermal energy and thus requires less aggression for each consecutive batch - this sort of thermal retention is my best friend when it comes to the systems I use.
    Ah ok fair enough, nah appreciate all your thoughts. I believe in the manual it does say that you should wait an hour between roasts, but I do know many here don't necessarily go by that and say it should be fine to go sooner.

    Ah I did just remember that in my last roast I DID forget to put in the chaff tray, but I wouldn't think that would make much of a difference, as all it does is catch chaff. Unless it affected airflow or something hmmm...

  25. #25
    Mal Dimal's Avatar
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    Quote Originally Posted by simonsk8r View Post
    Unless it affected airflow or something hmmm...
    Bingo...

    Mal.

  26. #26
    Senior Member simonsk8r's Avatar
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    Behmor Coffee Roaster
    Quote Originally Posted by Dimal View Post
    Bingo...

    Mal.
    AH! Goodness, would never have thought that would affect things haha, but yeah the chaff tray does take up a bit if room in the roaster... I'll be keeping on my toes next time ;D. Cheers Mal a great help as always
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