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Thread: Interesting Articles - Roasting Concepts

  1. #1
    Senior Member CafeLotta's Avatar
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    Interesting Articles - Roasting Concepts

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Came across a couple of interesting articles discussing roasting concepts. A fair bit of info in amongst it all. The odd reference to Behmor is in there too.

    Hopefully I haven't duplicated these links from anyone's previous posts.

    https://www.perfectdailygrind.com/20...e-temperature/

    https://www.perfectdailygrind.com/20...rate-rise-ror/

    https://www.perfectdailygrind.com/20...erent-origins/


    The flavor wheel has appeared before but probably fitting to add it here as well.

    11x14 Flavor Wheel.jpg
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  2. #2
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    Quote Originally Posted by CafeLotta View Post
    The odd reference to Behmor is in there too.
    They being a sponsor of that site and two of the three articles.
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  3. #3
    CoffeeSnobs Owner Andy's Avatar
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    aaarrrgghhhh... head - wall - bang - bang - bang.
    are you trying to get rise out me CafeLotta?

    Those are exactly the sorts of articles that you have to be careful reading, even more careful sharing. Lots of misinformation and fluff written well enough to appear credible. The Internet is bursting at the seams with that stuff which is why I posted this simplification of the process today.

    Article 1:
    Charge temp on a Behmor, Breadmaker, Popper, Hottop, etc makes near zero difference except you will chase your tail trying to repeat it. A domestic roaster started at ambient will always be about the same starting temperature (in Australia) as weather that we all roast in is much the same year-round. In small roasters with low mass, starting from 20-25C is very repeatable and your error margin is small. You are better off adjusting your bean weight to suit the temperature than trying to preheat.
    If you heat to 200C and then drop beans in there is a chance that you are actually starting the process at 180C, 150C, 120C and it's only a few seconds difference in door open or lid-off to do that.

    Low roaster mass = quicker heat dissipation.

    In a commercial roaster the huge amount of ambient air drawn in creates the biggest differences and the person operating the roaster has a level of control over that. The large (heavy) drum mass does need pre-heating to get it to operating temperature and is proportional to both the roasting drum mass and the bean mass dropped into it (along with the temperature of the stored bean). Remember we are talking about 10kg-60kg of beans into a 50kg-250kg mass of drum... very different numbers and trying to replicate this on a domestic appliance will send you insane.

    Article 2:
    Rate of Rise is important on a large roaster as it gives a better indication of where you are heading before you get there. Again, on a home roaster it has less importance and chasing an Internet quoted rate of rise will have you tipping beans or baking roasts. Use it as a loose guide to direction. The only time C/min is really important is if you want the gap between 1st crack and 2nd crack to be a specific "2 minutes" then you will need less than 7C/min heat or maybe you wanted it to be "5 minutes between" then you want 3C/min. Use it for math to replicate a known good roast, not a magic pill to bean development.

    Article 3:
    Bean densities. Arrgghhh, I hate this one especially. Okay, if you have coffee from a low altitude island (Australia, Jamaica and some of Hawaii) then yes, it will have a lower density than most of your green beans and will require a slightly gentler roast. Everything else, nearly every Arabica coffee in the world will have a very similar density. The bean decides this and it will only grow in a narrow altitude band (by choice) so the differences are actually tiny.

    Easy enough to test this yourself. Grab a glass jar, add 500g of a green bean and texta the height on the jar, grab another 500g of something else and do the same... the texta marks will be very close. If you want to do an even better job of this then preheat each of the 500g lots to 120C in your roaster then cool them, that should be enough to release most of the water and create a more level playing field. The density markings will be even closer.

    We have packed many thousands of 15kg green bean buckets from hundreds of different origins (and processes) and the difference between the highest and lowest density would be under an inch in a 18inch high bucket (ie: 5%)

    Low density island coffee and high density beans (mostly older varietals like Yemen, Harrar etc) will be a bit different to roast but it's just a matter of making small adjustments to your profile.

    Indo wet hulled coffee will have a higher moisture content which can lengthen a roast to get on the same track and something like a monsoon bean which is very dry will shorten a "normal" roast profile length. Again, you will know this from a previous roast and will have a profile to suit.

    I understand the desire to consume articles like those linked but please take them in context. They are produced by people that need to talk about something.

    Please believe me, the single biggest difference you can make to your home roasting is to taste the results and make notes of what works well on your equipment and what doesn't.


    (rant over)

  4. #4
    Mal Dimal's Avatar
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    G'day Andy...

    This "rant" (or great info) would be worth pinning up I believe to assist folks starting out and some of us older CSers too, coming from someone like yourself it really means something.

    Mal.
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  5. #5
    CoffeeSnobs Owner Andy's Avatar
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    Thanks Mal.

    I was going to write a book but I can't fill the first page...



    green bean + heat + agitation = brown, taste it, make some notes.

    make 1 change:
    green bean + heat + agitation = brown, taste it, make some notes.

    make 1 change:
    green bean + heat + agitation = black, smell it, toss it, make some notes not to do that again.

    make 1 change:
    green bean + heat + agitation = slightly yellow, taste it, toss it, make some notes about hipsters.

    make 1 change:
    green bean + heat + agitation = brown, taste it, make some notes.

    make no change, last one was good:
    green bean + heat + agitation = brown, taste it, make some notes (did I replicate it?).



  6. #6
    Senior Member CafeLotta's Avatar
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    Quote Originally Posted by Andy View Post
    aaarrrgghhhh... head - wall - bang - bang - bang.
    are you trying to get rise out me CafeLotta?

    Those are exactly the sorts of articles that you have to be careful reading, even more careful sharing. Lots of misinformation and fluff written well enough to appear credible. The Internet is bursting at the seams with that stuff which is why I posted this simplification of the process today.
    No, not deliberatley trying to get a rise but must admit it is educational when it happens.

    My bad. I must admit I did skim through these and thought there appeared to be some interesting content in there. As you rightly stated, there's a lot of stuff online and alot of it misinformation. The intention of posting articles like these was to hopefully find some interesting and informative content in amongst it all, generate some discussion (tick) and possibly get some entertainment out of the articles (tick?).

    I didn't think my post read as "this is gospel" but if that's how other's read it then I'll need to be a little more attentive to the abridged wording in future posts.

    We're all on a learning curve and if it was as easy as being able to go directly to 100% reliable and accurate sites, we probably wouldn't have Forums like this.

    Thanks to Andy for the content provided above as this we do know has come from a reliable source.
    Last edited by CafeLotta; 2nd December 2018 at 11:40 AM. Reason: 42
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    PerfectDailyGrind... take everything you read there with a grain of salt.

    RoR - quite possibly my least favourite examples of coffee jargon.

    I hear Andy on bean density - another example of confusing coffee jargon.

    The issue is that what is actually being measured when roasters use the method Andy describes above is not the bean density (i.e. the density of the green beans), but the bulk density (the average density of the beans and the air between them).

    Take a sample of beans and measure the bulk density. Then, break the beans into smaller pieces and measure it again. The bulk density will go up, with no change in the bean properties at all.

    There is potential for confusion and misinformation when "bean density" is used as the basis for understanding or explaining roasting behaviour.
    Last edited by MrJack; 2nd December 2018 at 03:53 PM. Reason: clarification
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  8. #8
    Mal Dimal's Avatar
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    Quote Originally Posted by MrJack View Post
    RoR - quite possibly my least favourite examples of coffee jargon.
    What would you use to describe a segment of the roasting profile with temperature and time the main axes of interest?

    I tend to prefer using "gradient" to describe what ever portion of the profile I'm focussing on but in reality, it is still a rose by another name that, err... Smells the same.

    Mal.

  9. #9
    Super Moderator Javaphile's Avatar
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    We could always break out the slide rule and differential calculus and functions and tangents, but do we really want to go there?!?


    Java "Slide what?" phile
    Toys! I must have new toys!!!

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    I'm not entirely sure why I dislike it so much. Slope or gradient would be fine, used in context.

    I think perhaps it is because RoR has become roasting jargon and is thus often used in isolation, with no reference to temperature or time. This gives the impression that RoR is some unknown variable specific to coffee roasting, rather than something very simple to explain and understand.

  11. #11
    CoffeeSnobs Owner Andy's Avatar
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    Quote Originally Posted by CafeLotta View Post
    We're all on a learning curve and if it was as easy as being able to go directly to 100% reliable and accurate sites, we probably wouldn't have Forums like this.
    I think the opposite it true.

    CoffeeSnobs forum has a history of editorial (eerrr... read:"Andy's grumpy old man rants") to try and keep the content reliable and accurate when it starts to go too far off-track. The other sites need to keep producing new content and to pimp the latest idea/book/equipment/personality and are typically produced by someone who doesn't roast coffee to feed the family.

    In my arrogance, I can see no real reason to go anywhere else except for a light laugh or a tsk tsk and CoffeeSnobs has produced many great commercial roasters over the years who started with a popper on the forum.

    Oh, and on the topic of ROR... You might notice I never use the term nor ever quote it as a "fix". I actually think we might have invented the idea in Roast Monitor with the C/min (10 years ago in version 1 of Roast Monitor), it was a long time before it was trendy and I suspect a couple of book authors might have borrowed it from us. I'm used to getting blamed so yeah, "our fault".

    Speaking of authors... not naming names but over the years I've had coffee produced by some of the world's leading authors and was less than impressed by all of them. The reason Aussies have done so well at Barista comps all over the world in the last 15 years is that it's an Aussie tradition to "cut your own path" and try something different. Results based on flavour, not marketing\promotional fluff.

    Is it a full moon? I keep writing like this. Sorry, I'll get back on the roaster.
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  12. #12
    Senior Member CafeLotta's Avatar
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    Quote Originally Posted by Andy View Post
    Is it a full moon? I keep writing like this. Sorry, I'll get back on the roaster.
    Could be the adrenaline of the past week stretching out the effects of the full moon on 23 Nov ?

    Quote Originally Posted by CafeLotta View Post
    We're all on a learning curve and if it was as easy as being able to go directly to 100% reliable and accurate sites, we probably wouldn't have Forums like this.
    This wasn't a dig at CoffeSnobs but meant to be the opposite. Lost in translation? Need to stop speaking like Yoda, I do.
    Last edited by CafeLotta; 2nd December 2018 at 06:47 PM.

  13. #13
    Senior Member Lyrebird's Avatar
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    Quote Originally Posted by Javaphile View Post
    We could always break out the slide rule and differential calculus and functions and tangents, but do we really want to go there?!?


    Java "Slide what?" phile
    Yes we do.

    Rate of rise is simply dT/dt where T is the temperature of the bean mass. If we assume that the thermal capacity of the beans is a function of moisture which is itself a function of bean temperature (which it is according to this paper) we can derive the total heat input to the coffee from the dT/dt curve.

  14. #14
    Senior Member Barry O'Speedwagon's Avatar
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    Quote Originally Posted by Lyrebird View Post
    Yes we do.

    Rate of rise is simply dT/dt where T is the temperature of the bean mass. If we assume that the thermal capacity of the beans is a function of moisture which is itself a function of bean temperature (which it is according to this paper) we can derive the total heat input to the coffee from the dT/dt curve.
    I guess we could do, but unless the external conditions are constant it wouldn't be super useful. And even if external conditions are held constant, different beans like heat applied at different times during the roast, so you could end up with the same integral for very different roasts (in the practical world).
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  15. #15
    Senior Member Lyrebird's Avatar
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    If you have different profiles with the same integral the difference is in the dT/dt curve so you've kind of proven my point.

    In any case I have found looking at the heat accumulation quite useful. As an example, comparing incoming energy to the heat accumulation, I have not been able to measure any significant exotherm in a normal roast profile.

    I am now of the opinion that the only time beans are really exothermic is if they are burning.
    Last edited by Lyrebird; 2nd December 2018 at 09:48 PM.

  16. #16
    Mal Dimal's Avatar
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    Quote Originally Posted by MrJack View Post
    I'm not entirely sure why I dislike it so much. Slope or gradient would be fine, used in context.

    I think perhaps it is because RoR has become roasting jargon and is thus often used in isolation, with no reference to temperature or time. This gives the impression that RoR is some unknown variable specific to coffee roasting, rather than something very simple to explain and understand.
    Ah Ok.
    I get where you're coming from...

    Mal.

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    Well that was a wasted read

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    Senior Member LeroyC's Avatar
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    Interesting Articles - Roasting Concepts

    Quote Originally Posted by Gretsch View Post
    Well that was a wasted read
    The thread or the articles (or both)?

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    Behmor Coffee Roaster
    Quote Originally Posted by LeroyC View Post
    The thread or the articles (or both)?
    The articles.



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