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Thread: Fluid Bed vs Oven ( behmor) pros & cons

  1. #1
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    Fluid Bed vs Oven ( behmor) pros & cons

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Can you seasoned roasters out there provide feedback on Fluid Bed roasting approx 1 kg and an Over type roaster . Which is more even ?

    Thanks

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    CoffeeSnobs Owner Andy's Avatar
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    Even?

    Colour evenness the fluid bed is usually better
    ...but taste...
    drum wins every time. More body and more flavour depth in the result, fluid bed roasts are nearly always "soft".
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    Any clue as to why?

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    Quote Originally Posted by MrJack View Post
    Any clue as to why?
    Yes- convection only roasts are not the same as roasts which incorporate a proportion of conduction.

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    Senior Member deegee's Avatar
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    Quote Originally Posted by Talk_Coffee View Post
    Yes- convection only roasts are not the same as roasts which incorporate a proportion of conduction.
    This may be the "how", but like Mr.Jack, I am interested in "why" a convection roast is different.
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    I'm assuming it's related to moisture content, but was curious if anyone knew.

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    Quote Originally Posted by Talk_Coffee View Post
    Yes- convection only roasts are not the same as roasts which incorporate a proportion of conduction.
    It's not really clear to me why conduction would be inherently different. The inside of a bean is influenced only by the bean surface conditions - assuming they were the same, the mode of heat transfer is not relevant.

    So, what I would love to know is what is the difference in bean surface condition (between drum and fluid bed roaster)? Perhaps it is simply a matter of changing the operating conditions in a fluid bed roaster?

    Perhaps "evenness" itself is the problem...

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    Senior Member Vinitasse's Avatar
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    I would imagine that air velocity has a lot to do with it. In a fluid bed roaster the air is moving a hell of a lot faster which would lead to a far faster drying phase as the moisture is literally stripped out of the beans far more efficiently than it would be in a conventional drum roaster. Kitchen ovens demonstrate this as recipes always call for shorter baking or roasting times in fan forced ovens. And... a quicker drying phase, shorter roasting time and, most likely, lower moisture content will ultimately result in roast (and flavour) profiles quite different to those from drum roasters.
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    Hi Andy. Can you clarify "soft"? I am interested in the Behmor , but I am going through the "create my own home made roaster" phase

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    Senior Member deegee's Avatar
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    " Perhaps "evenness" itself is the problem..."

    " And... a quicker drying phase, shorter roasting time and, most likely, lower moisture content will ultimately result in roast (and flavour) profiles quite different to those from drum roasters "

    I once stretched out a roast to over 20 minutes in one of my Frankenpoppers, with a slow ramp up, much as Matt and Mal do in their corretto's. As I recall, it was very even, but it was the worst result I had from that bean.
    My palate lacks the ability to describe it better, but flat, lifeless, bland, are all terms that spring to mind. I needed no further convincing that hot air roasts need to be kept shorter than most other methods.

  11. #11
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    Never used a "longer" profile with any of my Poppers, for the very reasons you discovered "deegee"...
    Found that the optimum roast duration was between 10-11 minutes for 95% of all the beans I tried.
    There's a lot of sense in what "Vinitasse" outlined above, in my opinion...

    Mal.
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    Quote Originally Posted by Vinitasse View Post
    I would imagine that air velocity has a lot to do with it. In a fluid bed roaster the air is moving a hell of a lot faster which would lead to a far faster drying phase as the moisture is literally stripped out of the beans far more efficiently than it would be in a conventional drum roaster. Kitchen ovens demonstrate this as recipes always call for shorter baking or roasting times in fan forced ovens. And... a quicker drying phase, shorter roasting time and, most likely, lower moisture content will ultimately result in roast (and flavour) profiles quite different to those from drum roasters.
    This is pretty much in line with what I suspect. In theory, it would be possible to compensate by control of humidity and temperature...

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    Behmor Coffee Roaster
    My experience with convection roasters leads me to agree with Andy. They produce a softer flavour, though I sometimes countered this with blending in some dark roasted Ethiopian beans.



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