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How does humidity really affect the roast?

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  • #16
    Re: How does humidity really affect the roast?

    Originally posted by rowdee link=1169177791/0#11 date=1169419488
    Hey JavaB I reckon the wind has a big influence on time and process. I tried roasting outside on a slightly breezy day on the premise it would help disperse the chaff and it was very strange in terms of times.

    Only tried it once more and went back to the security of my shed.
    Geoff,

    Yep, Im sure you are right.... Unfortunately there are very few still days here in Perth. All other relative distances (heatgun, bowl, fan etc) remain constant during the roast and from roast to roast.

    The movement of the chaff gives a good indication of what is happening to the air flowing over the top of the bowl..... and a gust of wind can defeat the airflow from the fan.... that must change the air pressure around the heatgun, therefore the airflow through the gun and the heat output....

    Plus the extra airflow (or reduced airflow in some cases) across the top of the bowl will also make a difference.....

    Yesterday... no breeze.... all the chaff cascaded out of the bowl and fell in a relatively small area.... for the first time ever! But if I tried roasting inside Id be dead ;D

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    • #17
      Re: How does humidity really affect the roast?

      Originally posted by JavaB link=1169177791/15#15 date=1169423865

      Yesterday... no breeze.... all the chaff cascaded out of the bowl and fell in a relatively small area.... for the first time ever! But if I tried roasting inside Id be dead ;D
      Thats what sheds are for, I can make as much mess as I like...although that said I cant stand mess so I sweep up after every few roasts!

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      • #18
        Re: How does humidity really affect the roast?

        Originally posted by rowdee link=1169177791/15#16 date=1169427302

        Thats what sheds are for, I can make as much mess as I like...although that said I cant stand mess so I sweep up after every few roasts!
        Geoff,

        Mmmm.... Well my problem is the shed houses a metal lathe, a wood lathe, a drill press, a saw bench..... etc

        Plus Im a certifiable hoarder of "come in handy stuff" - comes with being a committed tinkerer

        So there is no room to swing a cat - let alone set up a roasting station..... and cleaning up the chaff would be.... well.... impossible!

        The roasting station is on wheels and lives in the shed but gets rolled out for action.

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        • #19
          Re: How does humidity really affect the roast?

          While I cant reach any conclusion on whether humidity affects the roast time, I am positive even a slight breeze DOES slow things down -- at least on the barbecue.

          Wind can enter from the rear and under the burners to carry away heat. The lid itself must have heat transferred away from it.

          On a particularly windy day, turning down the burners to very low is useless because the flames get blown out altogether, making temperature control rather difficult.

          --Robusto

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          • #20
            Re: How does humidity really affect the roast?

            Originally posted by robusto link=1169177791/15#18 date=1169515549

            On a particularly windy day, turning down the burners to very low is useless because the flames get blown out altogether, making temperature control rather difficult.

            --Robusto
            Which is why I love the BM and HG for the control!

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            • #21
              Re: How does humidity really affect the roast?

              Even the corretto is subject to wind.

              Dont think my TOP roaster is affected by wind, because the roast chamber is nearly sealed, but then again, I roast in the garage, and only have to worry about ambient temperature, which has negligible effect in my case.

              Humidity only really has a major impact post-roast, where the beans quickly take in moisture from the surrounding air.

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              • #22
                Re: How does humidity really affect the roast?

                Yeah,

                Youd think a Corretto would be adversely affected by wind. Up here on the Southern Downs where we live, windless days are a rarity and about 22 out of my last 25 roasts have been pretty breezy. It doesnt seem to affect the roast times though as they have remained very constant right from when I first started getting a handle on the process with the Corretto. It may have more to do with the Heat Gun I have though as it blows a fairly strong stream of hot air....

                Mal.

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                • #23
                  Re: How does humidity really affect the roast?

                  Do you get motion sickness at all living up on the Downs?

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                  • #24
                    Re: How does humidity really affect the roast?

                    Originally posted by nunu link=1169177791/15#20 date=1169555242
                    Even the corretto is subject to wind.
                    Which is why I should have added the proviso that you did about roasting indoors which solves that problem.

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                    • #25
                      Re: How does humidity really affect the roast?


                      Well, Im coming into this conversation pretty late, due to being away for the last 2 weeks, but am anxious to try out roasting in very humid conditions.

                      It is almost midnight here and its 26C at over 80% humidity.
                      Id love to roast now but itll have to wait a bit ;D gotta unpack bags first too :-)

                      My theory is that the green beans must be absorbing more moisture even before the roast begins. As I believe Andy has pointed out would happen in the northern areas of Aust. At the end of the roast the normal loss would occurr eg 16 - 18%. However I dont believe the actual roast would be any different to a normal one. Not in the BM anyway. However I shall see in a day or so.


                      Belinda

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                      • #26
                        Re: How does humidity really affect the roast?

                        If the beans themselves have been sitting in the 80% humidity long enough to absorb additional moisture you might try a drying period at the beginning of the roast. This seems to be pretty SOP for commercial roasters dealing with high moisture content beans.


                        Java "Trys to avoid wet beans." phile
                        Toys! I must have new toys!!!

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                        • #27
                          Re: How does humidity really affect the roast?


                          How would you do this drying period Java" "phile ??

                          low heat for a few minutes?

                          Belinda

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                          • #28
                            Re: How does humidity really affect the roast?

                            I was wondering if it had something to do with the airt pressure too. I am not that great at physics but isnt there an increase in air pressure in high humidity? Could this possibly affevct the roasting times/temps/variables etc etc.

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                            • #29
                              Re: How does humidity really affect the roast?

                              Originally posted by Corretto link=1169177791/15#26 date=1169699157
                              How would you do this drying period Java" "phile ??

                              low heat for a few minutes?

                              Belinda
                              There seems to be two approaches to this. One is to use a low temp and dry the beans to a normal moisture content level before proceding into higher temps and the actual roasting phase. The second method is to slow down the ramp up to first crack.

                              From what Ive seen it appears the first method is favored for beans with a really high moisture content while the 2nd is more commonly used for beans with just a slightly elevated moisture content.


                              Java "Its all relative!" phile
                              Toys! I must have new toys!!!

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                              • #30
                                Re: How does humidity really affect the roast?


                                ah but how can one tell how much moisture content is in a bean without the correct instruments (whatever they are) ?

                                I suppose one could weight them every day and see how much they change in weight :


                                Belinda

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