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Possible to achieve 1C at low temps?

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  • Possible to achieve 1C at low temps?

    Hi Guys,

    Newbie to roasting. Just wondering if it is possible to roast (get to and beyond first crack) using lower than "normal" roast temps?

    My reasons for asking is that my roaster indicates a temp of 117 when i drop, and 1st crack occurs at/near 140 degrees around 10 mins in

    My initial roast was done dumping at 205, but the beans cooked extremely quickly (about 6 mins).

    Im guessing i may have probe issues, but my brain isn't comprehending why.

    help and advice most appreciated. Cheers

  • #2
    What kind of roaster and what kind of probe do you have?

    The beans won't roast at 140°C (let alone 117°C) so are obviously at a much higher temperature than is indicated.

    My guess is that either the temperature at the probe is lower than at the beans, the rate of heat transfer to the probe is really slow or the probe is massive (i.e. the probe temp lags behind the actual temp). Unless there is some other (electronic) fault.


    • #3
      As per Mr Jack, you'll need to tell us about your roaster and the type and location of the probe. You also need to ensure the probe is completely covered by the beans so it is measuring bean mass temp and not air temperature


      • #4
        I agree with the above 2 posts, we all need more information to help troubleshoot your problem properly.

        If you are getting 1st crack at 140C then your reading is out by exactly 40% at that temperature.

        Intrinsic to the clever Arabica bean design is a built-in "thermostat" that causes them to crack at 196C.

        Errors in probe placement, the amount of beans you are getting a measurement from, probe and device fluctuations can add-up to a plus or minus 5% error normally so the 1st crack range should be more like 185C to 205C.

        I assume you are not using a HeatSnob as that's a far bigger environmental error than I've ever seen.


        • #5
          Originally posted by Andy View Post
          Intrinsic to the clever Arabica bean design is a built-in "thermostat" that causes them to crack at 196C.
          The above is true at sea-level (ish) where nearly all Aussies live, I would be interested to hear from others if it's also true when you are roasting at much higher altitudes?!?!


          • #6
            I'm at 500m, not that high but I know from beer making that my water boils @98.5. With coffee beans first crack is between your parameters, usually 185-195. Even on top of Mount Kosciusko (2200m )water boils at 92C, not a huge difference, beans wouldn't be much lower I'd guess.


            • #7
              Its a roast.max roaster. 10Kg lpg fired.

              Probe placement.seems is.a.fairly thick probe (thinking 3-4ml).


              Btw, ill.check.out.this heat.snob.thing Andy. Cheers


              • #8
                I too have a Turkish made roaster (Akaneks) with ridiculously thick probes and the temps they read straight from the factory weren't even close to reality except when sitting idle at room temp. I have installed smaller, much faster reacting k-type thermocouples and it hasn't been an issue since