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  • temperature for roasting in corretto

    Hi there to all experts in coffee land.
    I have been using the BM and an el-cheepo heat gun for a month or so now but was given a new fandangle heat gun for xmas. While this is great my problem is that i can set the gun to any temperature that i want up to 630 degrees and two fan settings.
    It has by default 3 fan settings
    • setting I only goes to 50 degrees
    • setting II goes  to 630 degrees
    • setting III also goes to 630 degress but with a higher fan speed

    I can then use the LCD display at the back of the gun to change the heat to what ever temperature i like.
    My question is what temperature would i set the heat gun to for roasting purposes, i notice in the fantastice post by Corretto that there are temperature changes at different stages of the roast, is this a function of the roast process ie., as the beans change or is it a change of temperature due to changing settings on the heat gun?

    Any suggestions?
    Thanks
    Bolb


  • #2
    Re: temperature for roasting in corretto


    Hi Bolb. The changes in bean temps are definitely the effect of the beans slowly (or quickly) heating. Generally the HG temps are left at the same setting for most of the roast, sometimes dropping the temp after the 1st crack, depending on the BM HG setup (they vary).

    If you look at the Datalogged Zip thread in this section youll see some graphs of the roasting process which show the gradual rise of the bean temps.

    Of course you really have to experiment with your setup to find the ideal HG settings. But generally youd want it near full until the first crack. Best variation is got by raising or lowering of the HG itself.

    Hope things are going well for you with that setup


    Belinda

    Comment


    • #3
      Re: temperature for roasting in corretto

      Hi Bolb,

      Given the max of your gun is 630 I would use setting III with the higher fan speed. Then if your roast is too quick you can cut back to II with the next one.

      Be interesting to hear how long to first crack.

      Comment


      • #4
        Re: temperature for roasting in corretto

        You can experiment with different profiles.... starting off hot for several minutes, backing off for a couple of minutes, then back to hot before once again using a cooler setting after first crack.

        This will affect the taste, and if youre keen enough, make notes and comparisons.

        -Robusto

        Comment


        • #5
          Re: temperature for roasting in corretto

          Thanks for the quick posts guys.
          From my reading of the forums here the beans should reach a temp of between 250 and 290 degrees, is this right?
          I thought i will have a go with the gun set to 250 and the higher fan speed and see how that progresses with a 300gm roast and see how it goes.
          Just off to build my bean cooling contraption so i post all results and thoughts shortly

          Thanks again
          bolb

          Comment


          • #6
            Re: temperature for roasting in corretto

            Originally posted by bolb link=1167177851/0#4 date=1167187934
            Thanks for the quick posts guys.
            From my reading of the forums here the beans should reach a temp of between 250 and 290 degrees, is this right?
            I thought i will have a go with the gun set to 250 and the higher fan speed and see how that progresses with a 300gm roast and see how it goes.
            Just off to build my bean cooling contraption so i post all results and thoughts shortly

            Thanks again
            bolb
            Yikes! The beans will vaporise at 290! They should go as high as 220 to 230, but that temp is measured under the bean mass.

            Yep, experiment, but the HG should be near the highest setting.


            Belinda

            Comment


            • #7
              Re: temperature for roasting in corretto

              Didnt know that one.
              But my highest setting for the heat gun is 630 degrees so thats definitely out of the question.
              I guess a first experiment at around 230 at the gun should be the order considering it would be slightly cooler in the BM.

              Bolb

              Comment


              • #8
                Re: temperature for roasting in corretto

                Originally posted by bolb link=1167177851/0#6 date=1167188967
                Didnt know that one.
                But my highest setting for the heat gun is 630 degrees so thats definitely out of the question.
                I guess a first experiment at around 230 at the gun should be the order considering it would be slightly cooler in the BM.

                Bolb
                Bolb, the HG should be left on its highest setting. Most of the heat from the HG is lost to the air, bowl etc and 630C at the tip of the HG will not translate to 630C on the surface of the beans.

                My HG is rated at 650C and I run it just below full power aimed about 10 cm above the beans. This translates to heating the beans to a final temp of around 220C 8-)


                Belinda

                Comment


                • #9
                  Re: temperature for roasting in corretto

                  Hi bolb,

                  Welcome to CoffeeSnobs [smiley=thumbsup.gif]

                  Actually, the temperature you set your Heat Gun to is really determined by the size of your roast batch..... For example, when I roast small batches of 150 grams or less, The HG is set to its lowest output, nominally 350 C, and the roast allowed to progress without further intervention with 1st Crack occurring at about the 8:00 minute mark and 2nd Crack starting at around the 14:00 minute mark.

                  With larger batches 300g+, I just set the HG to its highest output (only got two on mine , Low is 350 C and low air speed and High is nominally 650 C with a high air speed). Because the larger batches soak up the extra heat input, the roasts actually profile to around the same times with my setup except that when the 1st Crack is well under way, I reduce the HG back to Low and allow the beans to coast up to 2nd Crack.... If I left the HG on High for the entire roast, 2nd Crack will start much earlier, as in about 2 minutes after the end of 1st Crack, which is not really ideal and doesnt allow for the same level of roast control.

                  In the end, I guess you will just have to experiment a bit with your particular setup and see what works. Basically, you want the beans to get to 1st Crack reasonably quickly, in the region of 8:00-12:00 minutes and then 2nd Crack about 5:00-6:00 minutes after that but this is not set in concrete and you should allow your senses of smell, sight and hearing fine tune the optimum time to stop the roast and cool the beans. Its a great learning experience and it doesnt matter if you get it wrong the first couple of times as so long as the beans dont end up as charcoal, you will still be able to drink the brews from them a couple of days later .

                  All the best, and

                  Cheerio,
                  Mal.

                  Comment


                  • #10
                    Re: temperature for roasting in corretto

                    Hi all
                    Thanks for the times there Mal (great name by the way),
                    Did a roast of about 450gms and stopped it just at the start of 2nd crack at about 19 min.
                    This new heat gun at 630 degrees is cooler than the el-cheepo i already had so the roasts go longer, previously stopping at a similar point in the roast for the same size i couldnt get them past about 14 min as a maximum.

                    Perhaps thats why the el-cheepo heat gun has the plastic surround starting to deform.

                    But on the end result this roast is much more uniform in colour and there are no black scorch marks at all (i used to get the occasional bean with scorching). with the old gun the beans would get a red glow from the element but this doesnt as the design is different. But definitely a much better looking roast than ever before.

                    Perhaps there is something to be said for a more expensive heat gun, before my next roast i will take some pics and post into both the heat gun and bread maker posts and give the stats on the equipment.

                    thanks for everyones input
                    Bolb
                    (Mal)

                    Comment


                    • #11
                      Re: temperature for roasting in corretto

                      Hi Bolb,

                      I should have said that my heat gun is rated at 750, but it is the temp of the beans, so the distance from them, that is the really important issue.

                      As the others have said, the experimentation is the important thing. I have been doing 300g roasts because it takes me about 5 days to drink. However, this last week I have done half a dozen 450g roasts for other people and that has been a great addition to my knowledge base.

                      I also document every roast and any changes I might make so that I can either replicate or eradicate it if something needs to be changed.

                      Comment


                      • #12
                        Re: temperature for roasting in corretto

                        Originally posted by bolb link=1167177851/0#9 date=1167215768
                        Hi all
                        Thanks for the times there Mal (great name by the way),
                        Wow!

                        A second "Mal" after all this time...... Dont feel so errr, unique now ;D. That roast looks excellent by the way so I wouldnt change too much with your roasting process at all. Youll have to post back after a couple of days with some cupping notes . What bean variety is it by the way?

                        Also, great advice there Rowdee about documentation..... Keeping accurate records goes a long way to help continuous improvement in the end result and is definitely worth doing.

                        Cheers guys,
                        Mal.

                        Mal.

                        Comment


                        • #13
                          Re: temperature for roasting in corretto

                          Mal,
                          That particular roast is a mix of colombian (60%) guatemalan (20%) and Indian Cherry Robusta (20%) it was just stuff i had left over and made up the bulk with colombian.

                          I generally do a 1/3 mix of each of the following, Colombian, Indian Cherry Robusta and Brazil Santos as the WAR Dept. here at home seems to find it a nice flavour, not bitter but plenty of oomph for the taste buds.

                          I am doing a 400gm batch today for the owner of a local roast chicken shop since he has provided me with some of the contraptions for my bean cooling etc.

                          Once i go to my bean supplier next week i will start again to take better records, i generally only roast the mix above and Unleaded (decaf) for a mate.

                          Have a safe and happy new year everyone.
                          Bolb

                          Comment


                          • #14
                            Re: temperature for roasting in corretto

                            Originally posted by bolb link=1167177851/0#12 date=1167280610
                            Have a safe and happy new year everyone.
                            Bolb
                            You too bolb [smiley=thumbsup.gif]

                            Mal.

                            Comment


                            • #15
                              Re: temperature for roasting in corretto

                              Originally posted by Corretto link=1167177851/0#7 date=1167190381
                              Bolb, the HG should be left on its highest setting.  Most of the heat from the HG is lost to the air, bowl etc and 630C at the tip of the HG will not translate to 630C on the surface of the beans.
                              Hi all,
                              incidentally I was yesterday measuring my el-cheapo HG output temps to get an idea about this. I have a HG with up to 600 deg C and it has a scale of 10 for the settings (and it has a inaccurate LED based reading of its internally measured temps). I have a different HG roaster setup (http://coffeesnobs.com.au/YaBB.pl?num=1164568191;start=all) and for this I always use the spreader (nozzle). So the temps (in deg C) measured right at the nozzle outlet were as follows:

                              HG setting claimed internal Temp Temp at nozzle output
                              (scale 10)
                              ------------------------------------------------------------------------
                              4 250 93
                              5 350 159
                              6 ~400 ? 212
                              6.5 ~450 ? 250
                              7 ~500 ? 270

                              I didnt go higher, as my TC is rated only at 300 C ...

                              So there is quite a significant drop (roughly by half), even without the additional cooling from colder air in BM, walls etc.

                              Another learning here at least for me was that one has to be quite careful when changing the HG temp settings: small changes lead to large temp chnages and so one should do small adjustments only, wait a bit, measure the effect on the bean (and/or chamber) temp , then adjust again, etc

                              In my setup (which probably behaves quite different from your HG/BM case) I only use the the HG settings in range 5.5 ... 7 , but according to above table this already covers about 100 deg difference at the HG output.

                              Cheers and happy fiddling Peter

                              P.S. there are at least 2 major threads here at CS about the HG/BM setup with thermocouples, going down this path is probably the best route to get an understanding whats going on in your BM roast chamber (even without data-logging). I bought 2 el-cheopo grill thermometers (at 9 EUR each), range < 300 deg, stainless steal enclosing of the shaft, etc.
                              For each roast I keep a log of temp readings each minute and it has greatly aided to get reproducible roasts.

                              P.S.S. But beware, its easy to start getting onto the path of the "mad scientist"; e.g. I am working a lot on my setup right now in terms of measuring the bean temp at various locations in the bean bed , + some chamber air temps, I just finished today the rigging for installing 6 TCs, but now after all these X-mas hams & turkeys all the thermomemeters are sold out :, so this may have to wait a couple of days ... arghh

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