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  • Exploding beans!

    As a relative newcomer to this home roasting gig (Im working my way through my first 5kg purchase), I was hoping for some advice...

    I am using a popper (Breville) to roast, and find I get a far more consistent roast using around 90grams of green bean. With this amount I can extend the roast out to about 8 minutes or so, depending on the ambient air temperature.

    I generally finish the roast 20-30 seconds into second crack, which I find suits my taste. I do notice however, that my beans tend to explode a bit during the second crack. The picture below illustrates the exploded beans. I realise this may in fact be what I am hearing during the second crack, but is this a fault in the roast?

    Many thanks all,

    Zaphod.


  • #2
    Re: Exploding beans!

    Divots are a normal part of popper roasting. Theyre usually caused by heating too quickly, as all poppers do.

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    • #3
      Re: Exploding beans!

      thanks nunu, i suspected that might be the case. so its fair to say its a characteristic one should try to avoid...?



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      • #4
        Re: Exploding beans!

        Yes, I get divots sometimes in the Imex as well. I rarely get them before 2nd crack and I have seen the occasional divot in pro-roasted coffee too.

        Rob

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        • #5
          Re: Exploding beans!

          Its unavoidable if youre using a roasting method that ramps up the temperature so quickly. If you can double your roast time, youd likely see zero divots in your coffee. Since thats highly unlikely with a popper, just accept it as normal and proceed.

          It is a widely held belief that popper roasting and such produce brighter coffees, roasts with higher acidity. If you like the end result of your work, then little visual imperfections are meaningless. It all gets ground up into powder anyway.

          The divots are a product of the failure of the physical matrix of the bean. If 2nd crack is the breakdown of the cellular structure of the bean, divots are just a more violent breakdown.

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          • #6
            Re: Exploding beans!

            many thanks for the explanation!

            i can see why in this quest for the perfect roast people resort to home made contraptions and mod-poppers! i may have to have a tinker around with mine...

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            • #7
              Re: Exploding beans!

              Is there a way to increase roasting time with an unadjustable Popper? As I have noticed the same thing with my roasts using a B&D popper and 105gms of greeen.

              Doppler

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              • #8
                Re: Exploding beans!

                Gday Doppler,
                When you say un-adjustable popper I assume you mean an un-modified popper. This leaves you with the two main things that will increase your roast time.
                1. The ambient temperature. If you can use the popper in a cool environment, youll extend the roast time as this will cool the air entering the popper. A bit like an inter-cooler on a turbo car.
                2. A smaller batch size, to a point, will allow a longer roast. The air in the roasting chamber wont get as hot due to increased air flow through the beans, and the less bean mass in the chamber reduces the heat retention of the beans.
                On the other hand, if you want to modify the popper, theres a few posts on here with examples of some easy, and not so easy, modifications you can make to your popper.
                Hope this helps.

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                • #9
                  Re: Exploding beans!

                  You can drop the batch size down to extend the roast. I try not to go less than 80-90g, otherwise my poppers never seem to reach 2nd crack.

                  Roasting in a walk in refrigerator is another way to extend the roast, but highly infeasible, unless you happen to have one at home.

                  Poppers by their very nature are ones to turbocharge a roast. If you want increased batch size/roast times, give a heat gun a go.

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                  • #10
                    Re: Exploding beans!

                    Gday Doppler,
                    If you happen to frequent any American sites, youll see a lot of references to using extension leads on their poppers to extend the roast time.
                    This wont have any effect here due to the vast differences in US and Aussie mains voltage.
                    All the best.

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                    • #11
                      Re: Exploding beans!

                      Thanks Guys will I will try this next weekend

                      Doppler

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                      • #12
                        Re: Exploding beans!

                        Doppler,

                        after messing around with the popper trying all sorts of ways to increase cool air flow into the chamber, and being on the verge of buying an appropriately rated light dimmer switch to decrease the voltage to the heating element, i went to bunnings and bought a $14.88 heat gun. Result? Even and longer roasts. No divots. And no problem doing batches of 250+ grams. The popper is destined for the recycle heap.

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                        • #13
                          Re: Exploding beans!

                          You can always send it to me...I need one to roast batches while my other two are offline cooling :

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