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First roast with corretto + PNG Wahgi

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  • #31
    Originally posted by Dimal View Post
    The closest I could describe this sensation, was to that of the zing-fizz that I experienced as a kid when I ate a Sherbet lolly or powder. Still does this for me...

    Mal.
    Yep, the lemon sherbet is one of the closest to good, sweet acidity. Quite different to unpleasant sourness.

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    • #32
      Originally posted by Dimal View Post
      With regard to attempting to control the Environment Temperature (ET) within a Corretto Roaster, this is not really as important as it would be if, for example, you were roasting in a commercial or shop Drum Roaster where the Thermal Mass of the Drum assembly is significant. The Thermal Mass just isn't there within a Corretto bread pan. In fact, the bean mass would supersede the mass of most bread pans used in Corretto Roasters.

      Very slight variations in Heatgun output realise significant variations in ET in this situation, even a breeze blowing across the top of the Corretto causes ET variation to the point where attempting to control it is almost pointless. Far better in my opinion, gathered from experience over several years, is to consider the mass of the bread pan and the beans as an integral whole.... Corretto Roasters for the most part, are fan forced roasters (not fluid bed) and the immediate roaster environment plays only a very small part in the eventual outcome of the roasted beans, so much so that I completely ignore it...

      Mal.
      Just to add a different (friendly) view point in case others are interested in aiming for a higher standard.

      Controlling ET is important in any form of coffee roasting, period. Comparing different roasters thermal mass has nothing to do with it.

      Once a standard drum roaster with good air flow control has turned around / rebounded and settled into a steady ROR, the convection / conduction ratio is usually around 70 / 30 - 80 / 20 depending on design, with some other recirculating systems being more like 90 / 10. So they are in fact " fan forced roasters"

      The bread pans used for corretto do actually have a decent mass, they are metal after all and used for baking bread and a well insulated pan even more so.

      A well insulated and mostly sealed up correto setup is quite close in design to the large commercial batch rotating drum roasters.
      300kg of beans in a big rotating bowl with a few stationary vanes and hot air blowing down onto them. Typically they work close to 100% convection and give similar results to a fluid bed roaster where the beans are agitated by the hot air only.

      Cheers

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      • #33
        Hi Steve

        I certainly that agree you have a valid point - there is some thermal mass to consider in a closed corretto system - and if you are roasting small 200g batches, then that will certainly have a noticeable impact. However, once you get to the 500g-800g range the proportion of impact drops significantly… which is where a lot of corretto roasters sit in terms of normal batch size.

        With my 750g batches I do notice a fair difference in the initial drop / post drop input temps required when backing up batches in a hot roaster (as opposed to my initial pre-warmed roaster) - sometimes as much as 30-40° initially. But the main impact of this ET is at the very beginning of the roast.

        As the roast develops, I end up pretty much chasing down my usual gun input temps to produce my final profile. So I manage this difference by starting at 40-50° lower at the turning point to account for this E.T. but usually end up ramping more from around the 100° in order to keep up with my profile.

        So, in the end I agree with you both (how very post-modern - we're all winners!)

        E.T. is certainly an important consideration in very small corretto roasts (as it would be in commercial batch roasters I imaging - not that I would consider spending '000's on a roaster that does 150g batches! )

        But in the more usual corretto batch sizes of 400g+ (and let's be honest - most people go a corretto/KKTO route because they find their 100g-125g popper type batch size just too frustrating & slow) the actual impact of this E.T. on the roast is greatly reduced when compared to what is required to be output by the gun.

        But if someone want to give me a Probat or HG 5kg roaster? I'll happily experiment on the impact on larger batch sizes of all that lovely cast iron or stainless …

        Cheers Matt

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        • #34
          Originally posted by Steve82 View Post
          Sourness / green hay is pretty good sign of under development, which can happen just as much with long and slow roasts as it can with quicker roasts.

          If you want to roast quicker you need to balance your environment temp, which is mostly convection heat application with the load of greens. For quicker roasts to be sweet, balanced and fully developed you need to be roasting quick but with slightly lower environment temps. If you load up to much weight then you will have to push temps higher developing the outside but leaving the inside a touch green.

          So for a quicker roast, run your heat gun at about 280 - 300, for around 20mins and see what temperature the roaster gets stuck at. Tweak this setting so that it gives you something around 230 - 240°C reading from your probe.

          Then find a setting that gives you around 200°C for a charge temp, load 200g of green, at the turning point change the HG setting to that which gave you your max environment temp and let it run...just see what happens. Hopefully you will only have to adjust your HG setting down just a touch nearing the end of rolling first crack so you can get your desired development time without stalling or the roast running away. Depending on your set-up you may need to change your batch size even lower or a touch higher to achieve your desired roast parameters.

          A good starting point would be 6min to beans turning yellow, 4.5mins to first crack start, then 3.5min of development time.
          I've just had the time to properly read and take in what you're saying there, Steve.

          If I understand this correctly, the first part of your post is essentially finding what gun temperature gives me the ideal ET in my corretto (understanding that every corretto is unique and requires their own temperature inputs). Also, what I've learnt from your post is that an ideal ET is around 230-240, which is a tad (~20) higher than projected bean temperature at the time of drop.

          And then I run a small/200g roast as per your advice in the last part of your post.

          By testing with a smaller batch size, I'm minimising the effect the beans will have on the ET. I can then adjust batch size accordingly once I've worked it all out on a successful roast.


          Right?

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          • #35
            We'll have to agree to disagree Steve, as your experience and experiments do not parallel mine, and I have experimented an awful lot over the past fifteen years or so....

            And as Matt indicated, proportionally sized roasts within a Corretto setup are not at all practical or worthwhile for my situation. If all I wanted to roast at a time was 100-200g, I would have stuck with my modified Popper....

            Mal.

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            • #36
              I gave the method a go, that Steve suggested, but it seems that my corretto doesn't like the small 200g batch size. The probe was clearly reading ET more than bean temp. I ended up abandoning the roast when the probe temp was up to 230 degrees without hearing first crack.

              I thought I would use the same 200 degree ET upon load and take Matt's advice of 40 degree temperature adjustments. Obviously the high starting temperature skewed everything, so it ended up just as quick as my last fast roast. I've now run out of the 2.5kg Wahgi bag, but will definitely be purchasing more Wahgi so I can work towards nailing it.

              Roast #3 - PNG Wahgi
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              The other bean I bought was the Peru Ceja de Selva AAA. I've read this bean takes a full week to sit and develop, so I thought I'd roast two 500g batches of this tonight, too. The two roasts are quite different. One around 17 minutes and the other around 21 minutes (still trying to work out how to read the exact roast time from load to drop.)

              I loaded the template of my roast I did the other day, just for some sort of reference, and of course wanted to aim for a slower roast. It didn't quite work out that way and pretty much tracked degree for degree and minute for minute haha. First to second crack was a little better, but still had improvements to make. I had also dropped the loading ET to ~105 degrees but it seems it wasn't quite low enough, still.

              Roast #4 - Peru Ceja de Selva AAA
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              I thought I would go for the other end of the scale for the second roast. Seeing it's usually milk based drinks in this household, when not taste testing, I tried for a darker roast (without knowing when to actually unload a darker roast). Over the last couple of roasts, I'd noticed that Matt's suggestion for 40 degree temperature increments were a little too much for my setup, so I've come to the conclusion that 20 degree increments work well for this corretto. This provided quite a nice, smooth adjustment. I also dropped the loading ET temp to 85 and it seems like it could be a good foundation for a nice RoR. I ended up getting a little confident (or cocky?) and tried a little Seattle Dip I think I struggled to get it going again, though, so it tended to drag out a little. First to second crack was going ok at around 5-7deg RoR (if I recall correctly), but it started to get away towards the end of it.

              Roast #5 - Peru Ceja de Selva AAA
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              After all that, I think the three back to back roasts really improved my understanding on how my setup reacts to inputs. While the third roast did drag out a little long, it does seem much more under control than some of my others. I almost felt like I was in control, rather than reacting and trying to bring it back.
              Last edited by dan110024; 15 May 2015, 02:11 PM.

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              • #37
                Worthwhile experiments there Dan, and interesting results indeed....

                Really though, if you want to get some kind of a handle on what the ET is doing while roasting a batch, you really need two independent Metering setups to feed into the Data Logging software, including Bean Mass Temperature (BMT). That way, you can observe the two variables while the roast progresses and gain an appreciation of the interaction between the two. Trying to do it any other way is really just guesswork and pretty well impossible to establish what is affecting the roast outcomes. It's just not possible to determine any correlations...

                Still, the effort you have applied is very impressive and you have realised some important outcomes, and that's the main thing in the end.

                Mal.

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                • #38
                  I'd like to have a second temperature input, but I have read that it requires a second DMM, right? The best I could do at this point in time is insert one of the other standard thermometer probes that I have laying around. I wont be able to log it on the PC, but it should give me an idea of what the actual ET is doing if it's there to look at for long enough.

                  In the meantime, an additional DMM will join everything else on the 'odd things to buy' list

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                  • #39
                    Haha....

                    Yes, this terrific hobby is definitely one that seems to be a magnet for the acquisition of various interesting additional bits and pieces. And yes, you do need another DMM with t/couple (preferably identical) to do all this properly.

                    One of the big problems with Corretto Roasters, is that barely two of them are identical and so it makes it very difficult to make valid comparisons between each others' setups. Another reason why it's such a good idea to do what you are doing now, and experiment with your own setup to establish its own operating characteristics. That's what most of us have done here, right from the outset, to help get the best we can from the bean.

                    I haven't used my second thermal data logger for quite a few years now, since once the empirical data was established for my Corretto, there was no real need to continue doing this. Monitoring and controlling via logging the BMT has been very accurate and consistent, so no need to make things more complex than they needed to be.

                    Anyway mate, keep at it since it's a lot of fun and the end results are a wonderful bonus....

                    Mal.

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                    • #40
                      Wow Dan - you're into it!

                      Don't worry about rest times - just into them Beans do develop over time - but I've found trying straight out of the roaster gives a really good understanding of the roast success of failure, and give the bets idea of bean characteristics - how they age after that is part of the journey

                      I think with the ramp, part of the reason could be your really hot pre-warm. I pre-warm to about 110-130° before loading (depending on time of year) and start the roast temp from 280 - 320 depending on time of year, with consistent 40° increments. 200° would really change this.
                      But, mine is also a larger batch size, which required substantial adjustment from my old 350g batches (if you've read any of the older 700g corretto thread)

                      Looking at those two profiles, I'd say first may be sour again, while the second may be a little flat in taste - you may find it quite powdery to grind and may choke up the machine until you go for a coarser grind. Most of that zing may disappear too.

                      Maybe next time, I'd think about working from your second profile, but pre-warm to 120° then trying 30° increments? The profile shape looks good, and after 1c looks good - just needs 'compressing' in the middle!

                      Cheers Matt

                      Comment


                      • #41
                        To make discussing the profiles a little easier, I've edited last nights post and labelled the attachments with the roast number.

                        Originally posted by DesigningByCoffee View Post
                        Wow Dan - you're into it!
                        I do tend to obsess over any new hobbies I come across although, they usually have a measurable impact on my bank account and social life...

                        Originally posted by DesigningByCoffee View Post
                        Don't worry about rest times - just into them Beans do develop over time - but I've found trying straight out of the roaster gives a really good understanding of the roast success of failure, and give the bets idea of bean characteristics - how they age after that is part of the journey
                        In the couple of threads I can find about Peru Ceja de Selva, they all say it really should be left a week. People are finding it's pretty average to begin with and then totally changes with time. I really need that Lido hand grinder to sample roasts with. I gave the grinder a thorough cleaning today....I should have thrown some in before filling it with that last batch of Wahgi. Oh well.

                        Originally posted by DesigningByCoffee View Post
                        I think with the ramp, part of the reason could be your really hot pre-warm. I pre-warm to about 110-130° before loading (depending on time of year) and start the roast temp from 280 - 320 depending on time of year, with consistent 40° increments. 200° would really change this.
                        But, mine is also a larger batch size, which required substantial adjustment from my old 350g batches (if you've read any of the older 700g corretto thread)
                        Are you talking about the first profile (Roast #3) I added from last night? I agree, 200° was way too hot. The second roast (roast #4) had a loading ET temp of roughly 105°, which still seemed a little warm and caused a fast ramp initially. Roast #5 had a very stable 85° loading ET, with a gun temp of around 100-110°. I think this provided the nicest turn over and initial ramp....would you agree or rather have a different opinion?

                        I found your thread regarding corretto batch size to have a lot of valuable information in it. I might go through it again, now that I've had experience 'doing' and understand the process more.

                        Originally posted by DesigningByCoffee View Post
                        Looking at those two profiles, I'd say first may be sour again, while the second may be a little flat in taste - you may find it quite powdery to grind and may choke up the machine until you go for a coarser grind. Most of that zing may disappear too.

                        Maybe next time, I'd think about working from your second profile, but pre-warm to 120° then trying 30° increments? The profile shape looks good, and after 1c looks good - just needs 'compressing' in the middle!

                        Cheers Matt
                        Again, you don't think that 105° loading ET (Roast #4) created too much of a fast temperature rise right after the turn over? I think the problem with the roast #5 (with the 85° loading ET) was that I was a bit slack in increasing the temperature after turnover, which your advice for 30° increases could fix.

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                        • #42
                          Yeah, sorry. Getting your profiles mixed up

                          I think you'll get a pretty good result out of Roast #4 FWIW. The smoothness mirrors the smooth heat inputs etc. Time is pretty good overall too.
                          If I was to tweak that profile myself, I think I'd take 10° off each gun increment up to 1C (which on the Bosch will equate to about 1-1.5 minutes longer over that zone) and then add 10° onto each of your temps post 1C to speed that up a little.

                          As I've been tweaking the post 1C zone, I've found that leaving the heat on and not dropping the temp until just into 1C (about 202° on my setup, which is 2° after 1C starts proper) and then dropping 30° every 5° from there on gives me the best results. But then again, that is my larger batch size.

                          But looking at your profile, if you had left that temp of 420 until 202, then dropped to 390 at 207 etc, 360 at 213 etc, you might get a smoother, slightly faster ramp.

                          But once again - into the cup with them and see what you think

                          Matt

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                          • #43
                            I'm going to do another roast of the Ceja de Selva in a week, so I'll apply that advice to it then Thanks!

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                            • #44
                              A bit of a random post/thought but not worth creating a thread for...

                              When I am tasting an espresso, why does the very last sip taste slightly different? I'm picking up sweeter notes whenever I finish it off. Is this something that could be happening or is it a psychological thing, being the last sip and wanting more?

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                              • #45
                                Probably depends a bit on just how long it takes you to finish off an espresso, as flavours can get a little sweeter as the espresso cools.

                                Also, might just be down to the fact that the initial hit of bitter-sweetness takes the edge off the bitterness due to an overpowering affect of these particular receptors on the tongue.... Don't know really, but I have experienced this phenomenon myself so I know what you mean...

                                Mal.

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