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Thread: Roasting and bean density!

  1. #1
    Senior Member simonsk8r's Avatar
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    Roasting and bean density!

    Hey cool cats, I've done a silly amount of research this morning regarding general roasting approaches to different bean densities... and can't really find any conclusive guidelines. Or moreso I'm finding contradictory guidelines haha.

    What would be a good general guideline for roasting different density/altitude beans? I understand it is definitely dependent on the bean rather than exclusively altitude etc, but just looking for more general recommendations.

    Some of the info I've gathered:

    "Higher grown, smaller bean, SLOWER roast.
    Lower grown, often larger bean, QUICKER roast.

    ...

    Harder bean= slower roast, so it roasts more evenly all the way through

    ...

    For hard beans, roast with a relatively high initial heat and moderate heat in the final stage of the roast process. Examples: Kenya AA, Guatemala SHB and almost any coffee grown higher than 5,000 feet.

    For medium hard bean types, roast these with moderate initial heat and moderate heat in the final stage. Examples: Brazil, Sumatra, Java and most Latin American coffees grown lower then 5,000 feet.

    For soft bean types, roast these with low to moderate heat during the entire process. Example: Hawaiian coffees, Caribbean types and beans grown lower than 3,500 feet."


    I'm roasting up the rest of my Kenya AA beans today just to tide me over, and not sure what approach.

    Both approaches make sense logically (strangely...):
    - A harder bean needs higher heat at the beginning to penetrate through so that the inside develops evenly
    -A harder bean needs a slower roast, and low temp ramp up so as to make sure it roasts evenly and doesn't scorch the outside


    Kenya AA is a more dense bean, so to go P2 profile on my Behmor (ramps up quicker for full heat), or a slower P3-P5 profile...


    I had roasted this before but would like some more input as to this aspect (as I was just roasting according to what someone said and not really understanding bean density roasting approaches..).

    Any thoughts on soft/hard bean roasting would be great, thanks guys!
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  2. #2
    Senior Member greenman's Avatar
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    Hi Simon
    When I am roasting higher grown denser beans I use a higher charge temperature than when roasting a lower grown Brazil. With the less dense Brazil's I use a charge temp 10C lower than high grown Centrals etc, giving the Brazils a gentler ramp up to first crack to gradually absorb the heat throughtout, too much early heat and they will scorch on the outside and get tipping on the ends of the bean, the higher grown beans need a lot more heat to penetrate the entire bean structure.
    Happy roasting
    Trevor

  3. #3
    Senior Member simonsk8r's Avatar
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    Hey Trevor, thanks so much for your help appreciate it!

    That definitely makes sense to me... Just keep seeing very opposing thoughts on this, and I know that it's not a hard and fast rule (..... The pun...... wasn't intended but I'll take it!!!), and to really experiment with my own equipment and develop a style that works for me. The bean can vary greatly, not to mention so many other factors but I'll keep that in mind for sure.

    Thanks mate

  4. #4
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    The incorrect use of the word density by coffee roasters is the source of some confusion - and probably the reason there is no "hard and fast" rule.

    When people talk about density, the are usually referring to bulk density; which is the average density of the beans and the air between them. This is strongly dependent on the size of the bean, because this impacts the ratio of beans to air:

    Smaller beans = less air = greater bulk density.

    This is important for convective heat transfer (air to bean) and conduction between beans or between the beans and metals surfaces, primarily because of the amount of surface area per kg of beans (smaller beans = more surface area per kg).

    However, bulk density does not affect conduction within the bean in the same way that density of the beans (i.e. bean density) does. Beans with a greater density will have a lower thermal diffusivity, meaning heat will take longer to reach the centre of the bean (essentially because there is more mass between the outside and the centre to heat up).

    I suspect people use bulk density because it is easy to measure, but bean density and bean size will tell you much more about the roast properties.
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  5. #5
    Senior Member simonsk8r's Avatar
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    Ahhh right, very informative thanks MrJack!
    Understood some of that, some went over my head a little haha.

    So in terms of definitions, would you say bulk density is more related to size of the bean, and is an average density figure when all beans are lumped together in a bag (ie smaller beans means less air between them, more surface area, so therefore greater density average in that bag)?

    And bean density is an individual bean's density, the amount of air/space WITHIN a bean as opposed to around it (which is really the only important variable to look at in terms of density)?

    Or am I off the mark a bit haha?

  6. #6
    Senior Member shapeshifter's Avatar
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    I used to follow the higher altitude higher heat method but nothing I ever did on P1 was any good, sure it might have looked okay but it didn't taste okay.

    I sort of get the impression that P1 is for all the ++++ Americans who like their beans close to if not black and oily.

    I use P3 most of the time, P2 if I think a previous roast for a high altitude bean could have been better, P4 occasionally again depending on the bean, I have never used P5.

    I have played with the temperature changes but ultimately it's a great starting tool but I'm ready to move on. Mine developed an issue where it just cut off, no error, just would suddenly stop, isolated it to the side board.

    In the time I was waiting for the engineer to do some testing, I pulled out my UCR and have been using it ever since. Honestly after going back to it, and the fault in the Behmor being found I wasn't happy to go back to using it, soooo a mod is now happening to the Behmor. I had a laugh

    Something I found improved the Behmor roast by quite a bit was when FC happened, dropping the heat by at least 25%. I'd rarely ever get the full time between first crack and second crack that pressing C was supposed to do, dropping the heat extended that a little more and produced beans more to my liking.
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  7. #7
    Senior Member simonsk8r's Avatar
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    Quote Originally Posted by shapeshifter View Post
    I used to follow the higher altitude higher heat method but nothing I ever did on P1 was any good, sure it might have looked okay but it didn't taste okay.

    I sort of get the impression that P1 is for all the ++++ Americans who like their beans close to if not black and oily.

    I use P3 most of the time, P2 if I think a previous roast for a high altitude bean could have been better, P4 occasionally again depending on the bean, I have never used P5.

    I have played with the temperature changes but ultimately it's a great starting tool but I'm ready to move on. Mine developed an issue where it just cut off, no error, just would suddenly stop, isolated it to the side board.

    In the time I was waiting for the engineer to do some testing, I pulled out my UCR and have been using it ever since. Honestly after going back to it, and the fault in the Behmor being found I wasn't happy to go back to using it, soooo a mod is now happening to the Behmor. I had a laugh

    Something I found improved the Behmor roast by quite a bit was when FC happened, dropping the heat by at least 25%. I'd rarely ever get the full time between first crack and second crack that pressing C was supposed to do, dropping the heat extended that a little more and produced beans more to my liking.
    Ah good stuff shapeshifter. Yeah I also reckon P1 is too hard too fast, and doesn't have any heat drop off towards the end.

    Yeah I never really understood how different P3, P4 and P5 really were from each other... there are changes that I can see in the manuals graphs like the length of time it stays at 70% power, then 80% power, and it lengthens these parts as you go upwards to P5.

    But don't really know how that would apply to getting what you want out of roasts (knowing the actual effect of them). I guess trialling it would be the way to know.

    And yeah my Behmor has done that once haha, just turned off, no error! But it's been ok since.

    And I don't have the Plus model, just the first one, and yeah as soon as Rolling FC comes I open the door slightly to cool it down a bit, or else it just rolls right into SC, it's the only way you can alter heat and avoid that roll on haha

  8. #8
    Senior Member shapeshifter's Avatar
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    I have the original one as well, upgraded the front board when it became available. This is the second time something has failed, the first time I got errors, replaced a few things. I've had it since mid 2012.

    It's definitely a trial and error thing, you have to remember we all like different things, what one person likes another won't. When I buy others roasted beans I tend to like using blends that are designated espresso/black coffee, I use them with milk; and not like blends that say 'goes great through milk', big choc taste, etc.

    I roast to suit my 'appliance' which I personally don't think is something that happens instantly, it's little changes in learning, technique, etc. that happen almost subconsciously.

    As much as I detest majority of cafe coffee, even with good beans most have no idea, with such high turnover of staff, and the cafes themselves it's not surprising though that few can get it right. Anyway, where was I going, oh yeah, I still buy one every now and then, even if you don't personally like the taste of a coffee, you should still be able to tell the difference between something that is still a great coffee and something that 'tastes like mouse shit'.
    Attached Images Attached Images
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  9. #9
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    Shapeshifter looking at those lovely pics reminded me I have not had my 2nd coffee for the morning. Nice crema.

  10. #10
    Senior Member simonsk8r's Avatar
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    Behmor Coffee Roaster
    Yeah absolutely, great points there shapeshifter. All too often we disregard our own experience and intuition in favour of potentially outdated and irrelevant guidelines that are only applicable to very specific situations. Great reminder that majority of the learning is in experimenting.

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