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Thread: The Summer Conundrum… advice sought!

  1. #1
    Life-long Learner DesigningByCoffee's Avatar
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    The Summer Conundrum… advice sought!

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hi all
    As ambient is rising as the summer approaches, I've noticed some unusual roast activity.

    • Firstly, my first crack/second crack logged temps have increased by about 3 degrees (first crack has been 199 like clockwork for 6 months now - but now closer to 202. second crack has gone from 221 and I'm heading towards 224 now). Same beans, same blends, same technique.

    • Secondly, despite consistent technique, in the cup these same roasts/blends, even when dropped at similar points (ie just on second crack) are becoming more acidic to taste.

    I suspect that because the ambient is higher, my overall roast times might be creeping shorter - so is the solution to reduce the overall heat input during the warmer months and lengthen the roast out again? Or take the roast to a higher drop point? Or roast at midnight?

    How do others adjust for the warmer months?

    Happy roasting
    Matt

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    Senior Member insomnispresso's Avatar
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    You didn't mention if this is a popper/coretto?

    Just my thoughts - if you are roasting in a closed environment I wouldnt expect to see a temp change. From my limited experience I don't recall crack temps changing.. Except when making changes to the probe. I find that you will ramp faster when it's warmer but as you said heat can be dialed back

    If it is an open environment then it would hazard a guess that your observation is indicative of the inaccuracy (note not inconsistency) of your current probe placement. In this case I don't think it is necessary to try to manipulate anything to get the temp back to the initial probe temp

    Maybe the observation here that needs to be made is are you hitting first crack/second crack at around the same time as previously? I think this will be more significant than the temp first crack/second crack starts.

    As a general thing you are going to be able to burn off acids quickest starting on the lead up to second crack (when it starts smoking heavily), so as you said lengthening the roast should help you mute the acidity.

    Anyway hope it help =)

    Cheers
    Matt

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    Life-long Learner DesigningByCoffee's Avatar
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    Thanks Matt
    Fully enclosed & insulated corretto, really consistent & accurate probe placement. Don't think this would be the problem, unless I need to scour the probe tip?

    I've been surprised over the last 12 months how consistent this system & these benchmarks have been for me - hence my conundrum! For all this time, I could pretty much guarantee first crack at 199 with any bean just about - but in the last 3-4 roasts it's been higher across the board, even with same beans/technique.

    What's more telling is that my same basic roasting profile/technique is giving slightly under-roasted results every time in the warmer weather. But this could have something to do with not having any warm weather last summer, so not really experiencing hot weather roasting yet!

    Just wondering if others have ever needed to adjust their technique in summer. :-)
    Matt

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    Senior Member Yelta's Avatar
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    Quote Originally Posted by DesigningByCoffee View Post
    Hi all
    As ambient is rising as the summer approaches, I've noticed some unusual roast activity.

    • Firstly, my first crack/second crack logged temps have increased by about 3 degrees (first crack has been 199 like clockwork for 6 months now - but now closer to 202. second crack has gone from 221 and I'm heading towards 224 now). Same beans, same blends, same technique.

    • Secondly, despite consistent technique, in the cup these same roasts/blends, even when dropped at similar points (ie just on second crack) are becoming more acidic to taste.

    I suspect that because the ambient is higher, my overall roast times might be creeping shorter - so is the solution to reduce the overall heat input during the warmer months and lengthen the roast out again? Or take the roast to a higher drop point? Or roast at midnight?

    How do others adjust for the warmer months?

    Happy roasting
    Matt
    Morning Matt, I have been roasting in a single loaf partly enclosed Breville for approx three years and my numbers are very similar to yours.
    During the winter months I start my 725 gram roasts approx 100c hotter than in summer for same roast times, 1st and 2nd crack show up at about the same time regardless of season.
    I usually see FC at approx 200c, and do see a variation of a degree or two either way depending on bean variety.

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    Life-long Learner DesigningByCoffee's Avatar
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    Thanks Yelta
    It's interesting that there is that much difference in temp needed to maintain a similar length roast, esp in a closed system. I imagine SA has pretty hot summers? We're much more mild here in summer - but get really cold winters.
    I guess that as in most things in roasting there's a bit of trial and error involved - I might try dropping all my input temps 20deg and see where that gets us :-)

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    Senior Member Yelta's Avatar
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    Quote Originally Posted by DesigningByCoffee View Post
    Thanks Yelta
    It's interesting that there is that much difference in temp needed to maintain a similar length roast, esp in a closed system. I imagine SA has pretty hot summers? We're much more mild here in summer - but get really cold winters.
    I guess that as in most things in roasting there's a bit of trial and error involved - I might try dropping all my input temps 20deg and see where that gets us :-)
    Matt, by the time I notice I need to slow things down a little I find a drop of 20 degrees has very little affect, lowering the heat gun setting by 50c is more like it.

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    Life-long Learner DesigningByCoffee's Avatar
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    Good- oh - I'll give that a whirl over the weekend :-)

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    Life-long Learner DesigningByCoffee's Avatar
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    Well, the ambient has dropped right back for the time being - so have to wait for another hot roasting day - could be days or weeks away!
    But my 'ideal' profile worked perfectly this morning!

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    G'day Matt...

    Have noticed similar characteristics up here too mate, especially when the day-time temperatures can switch from ~20C to 30C+ in next to no time.

    Have found it is much better to control the roast profile via Rate of Temperature Change of the Bean Mass, rather than any fixed temperature setting as such. Batches from one roast to another remain much more consistent doing it this way I've found...

    Mal.

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    Life-long Learner DesigningByCoffee's Avatar
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    Cheers Mal
    If only it was as simple as one fixed temp procedure … maybe when I get my subterranean climate & humidity controlled roasting cave! :-)

    Temp adjusting for ambient it is then.
    Just out of interest - I think you've got the same gun - what ball park temp setting would you expect to raise/lower for an ambient rise of, say, 10 degrees?

    Matt

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    Life-long Learner DesigningByCoffee's Avatar
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    Well, couple more roasts under the belt, and I've got some more data :-)

    Looking back through my archives, my best roasts were achieved during winter with a very low ambient (7-8 degrees), giving first crack in around 13-14 mins then second crack around 4-5 mins later with my 'standard' inlet temp procedure.
    With ambient's up to 18-20 degrees, and using the same inlet temps, the time to first crack dropped to around 11 mins, while first crack-second crack remained pretty consistent. This gave quite sour results.
    After a few more roasts (having in mind that my corretto is fully enclosed and insulated - which I think reduces to some degree the variance caused by ambient temps) I've managed to get back to a comparable profile, and much better results in the cup.
    And the small adjustment needed were quite surprising! On my Bosch I only needed to drop my temp inputs by 20deg (of gun temp - 15 deg inlet temp) at all my steps leading up to first crack - after first crack and through to second crack I could keep them the same. I haven't done any real hot weather (amb 30+) yet - I'm sure this would require much more adjustment.
    But, got something to work with now - for every 10deg ambient drop 15deg inlet temp!

    That's the theory for this week, anyway :-)

    Happy roasting
    Matt

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    "Quote • Secondly, despite consistent technique, in the cup these same roasts/blends, even when dropped at similar points (ie just on second crack) are becoming more acidic to taste.
    I suspect that because the ambient is higher, my overall roast times might be creeping shorter - so is the solution to reduce the overall heat input during the warmer months and lengthen the roast out again? Or take the roast to a higher drop point? Or roast at midnight? "

    Have you read the "Stretchin out the Roast" articles at Sweet Maria's ?. There is some interesting stuff there along the lines of your queries.

    Before I read them I was fixated on extending the time between first crack and second crack. Now I'm trying harder to stretch the time before first crack and less concerned with the time after it, but I'm going to be struggling for the next few months. I don't want to get too deeply into major electrical mods on el cheapo poppers, but I suspect it might be where I have to go next.

    Because I roast small batches, I have stuck with poppers, even though I would really like the extra control that comes with a corretto. In summer I will probably have to roast very early in the morning, since that is usually the coolest part of the day where I live.

    Cheers, Leo.

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    Life-long Learner DesigningByCoffee's Avatar
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    Quote Originally Posted by leograyson View Post
    Have you read the "Stretchin out the Roast" articles at Sweet Maria's ?. There is some interesting stuff there along the lines of your queries.
    Hi Leo
    Will certainly have to track that down!

    Quote Originally Posted by leograyson View Post
    Before I read them I was fixated on extending the time between first crack and second crack. Now I'm trying harder to stretch the time before first crack and less concerned with the time after it
    I think this is the point I've reached too. I have played with taking the roast drop point higher (ie dropping at 224 instead of 222 etc) but all this has done is give me a sour bean with an oily/bitter/overroasted undertone! So I'm thinking the time to first crack is very much the key too…

    Did a lovely looking & smelling Mocha/Java yesterday with a longer first crack-second crack, and earlier drop point (CS8 ish) - we'll see how it cups in a week or so.

    Happy popper modding!

    Matt

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    Life-long Learner DesigningByCoffee's Avatar
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    Just had a read and some interesting roast articles on the Sweet Maria's site - but gee he roasts quickly! Most seem about 10-11 minutes all up…! :-)

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    Quote Originally Posted by DesigningByCoffee View Post
    Just had a read and some interesting roast articles on the Sweet Maria's site - but gee he roasts quickly! Most seem about 10-11 minutes all up…! :-)
    Yes Matt, in this series the times are akin to my popper roast times, which is one of the reasons they caught my attention when I first noticed them. In cool weather I can achieve these times with a popper, but in warmer ambient temps, I suspect my current methods will be tested.

    I have wondered whether they are typical times, or if they were deliberately kept short to accentuate the effects of prolonging just one stage of the roast, while keeping the others short, but I did find this in another section of the site

    " Q: How long does it take to roast coffee?"

    " A: Air roasts ideally take 8 to 12 minutes and drum roasts about 14 to 20 minutes."

    So by their standards the times are probably typical for an air roaster, but shorter than for a drum type.

    And that begs the question : Which is a corretto ??

    Cheers, Leo.

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    Life-long Learner DesigningByCoffee's Avatar
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    Fair question Leo :-)

    I've played around recently with a popper too, and on some cold days I got 15-20 minute roasts (though only with 50g batches!), and the results were great! Different to the corretto, but still great. But on a warm day - 5mins max and pretty ordinary IMHO (first roasts I've thrown away in a long time). Poppers can obviously be pimped with substantial electrical mods - but it was the batch size that bugged me. If I could repeat my 15min roasts - I'd still need to do 7 batches in a row for the week!

    I think with a corretto you've got a mix of both - radiant/conductive heat & air-roast. An uncovered corretto would be much more 'air roasted' - so maybe these work better for shorter roasts with higher input temps (which most users seem to do looking at the profiles on this site). But I think a covered/insulated corretto is closer to a drum roaster - I certainly find with mine that you I much lower input temps, but also need longer times - lots of playing recently seems to require at least 13mins to first crack to make the results truly drinkable. And the amount of heat that the pan holds by the end is pretty amazing - lots of deep radiant energy there!

    Not sure about that commercial roaster profile - but maybe if it is pre-warmed, it has a heap of additional radiant/cond mass that allows for overall shorter times? Maybe pre-warming the corretto substantailly could achieve this result too? Experiment for another day

    But for the time being looks like 17-18min roasts it is!

    PS just had some brews (doppio this morning & FW just then - 50/50 Guat & Yirg) from my reduced temp 'summer' profile - spectacular! :-)
    Back in the zone baby!

    Matt

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    Senior Member Yelta's Avatar
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    Been watching this thread with some interest, given it was pretty warm here today 36c decided to roast a batch of 725 grams, 600 Ethiopian Harrar and 125grams of Yirg.
    As usual started my 2/3 covered Corretto cold, today that was a touch over 30c, Bosch heat gun on blower setting 2, heat 450c.
    FC as usual at spot on 200c @ 18 mins, dropped the temp to 400c at this point and stopped the roast @ 22 mins, 224c, slightly lighter than I usually roast, between CS 8 to 9, nice even roast.
    I usually take my roasts to approx 230c between CS 9 and 10, will be interesting to see how this lighter roast turns out, will report back when I try it in a few days.

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    Life-long Learner DesigningByCoffee's Avatar
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    Quote Originally Posted by Yelta View Post
    FC as usual at spot on 200c @ 18 mins, dropped the temp to 400c at this point and stopped the roast @ 22 mins, 224c, slightly lighter than I usually roast, between CS 8 to 9, nice even roast.
    Hey Yelta
    My FC/second crack temps are now back in line with what I'd expect (very similar to yours @ 199-200 first crack). I drop lighter - 223 deg which is just before second crack, about CS 8-9. If I go to 225 - I'm in Mexican CS9-10 territory. But I only do 350g batches, which also changes the dynamic somewhat.

    Fortunately we don't have to deal with 30-35 degree ambient like you that much! But we have those -5 night roasts to content with :-)

    Interested to hear how it goes in the cup.
    Matt

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    Quote Originally Posted by DesigningByCoffee View Post
    Just out of interest - I think you've got the same gun - what ball park temp setting would you expect to raise/lower for an ambient rise of, say, 10 degrees?
    G'day Matt...

    Sorry for taking so long to get back to you - Managed to come down with Pneumonia of all things and I'm still recovering....

    Anyway, I've got an Electronic Makita HG but it doesn't have an LCD display of output temp's, etc. Not that I would use it with how I go about things. All my roasting is managed via the CS Roast Monitor software and display, with concentration on the actual roast profile against 'winning' templates that worked well in the past (hardly ever look at the HG Output position, except at the start of a batch). This works easiest for me, is very repeatable regardless of ambient conditions and so far, quite successful. Currently enjoying an absolute beauty....

    Hope this helps a bit mate.

    Mal.

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    Life-long Learner DesigningByCoffee's Avatar
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    Hi Mal
    Sorry to hear about the Pneumonia - bummer :-( Glad to hear you're on the mend though.

    So do you then 'surf' the gun adjustments simply based on you software rate of rise? Does the temp lag when you adjust temps cause any dramas?
    Matt

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    Quote Originally Posted by DesigningByCoffee View Post
    Hi Mal
    Sorry to hear about the Pneumonia - bummer :-( Glad to hear you're on the mend though.
    Thanks mate...

    Quote Originally Posted by DesigningByCoffee View Post
    So do you then 'surf' the gun adjustments simply based on you software rate of rise? Does the temp lag when you adjust temps cause any dramas?
    Matt
    Yes Matt, that's exactly what I do. There is a slight lag of course but I am able to pre-empt that pretty well, just by becoming familiar with the dynamics of the system overall. No dramas what-so-ever. If one was so inclined, you could automate this to an extent where the 'hands-on' element of control is removed, and you just establish Ramp/Soak profiles to do all this for you. I really don't want or need to do this to be honest. Andy's software does a lot more than I actually need, so it's all good.

    If I am doing a batch for which there is no template available, I just head back to my notes for previous batches of the same bean/blend and attempt to replicate the original roast data, and ultimately create a new Template to use in the future. These, of course, can be manipulated based on taste tests to address any perceived roast shortcomings - Nothing new really...

    To be honest, every roast batch is a new adventure, even if it was one I've completed plenty of times before. Always love the tactility of it all....

    Mal.

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    Senior Member Yelta's Avatar
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    Quote Originally Posted by DesigningByCoffee View Post
    Hey Yelta
    My FC/second crack temps are now back in line with what I'd expect (very similar to yours @ 199-200 first crack). I drop lighter - 223 deg which is just before second crack, about CS 8-9. If I go to 225 - I'm in Mexican CS9-10 territory. But I only do 350g batches, which also changes the dynamic somewhat.

    Fortunately we don't have to deal with 30-35 degree ambient like you that much! But we have those -5 night roasts to content with :-)

    Interested to hear how it goes in the cup.
    Matt
    Reporting back.
    So, after 3 days, how was it in the cup? prepared as a long black, quite drinkable, loads of crema, a little on the thin/watery side for my taste, there is no question, I tend to prefer my roasts on the dark side, perhaps it will improve over the next few days.
    I'll drink this lot without complaint, however my next batch will certainly stay in the roaster a little longer.

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    Life-long Learner DesigningByCoffee's Avatar
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    Quote Originally Posted by Dimal View Post
    If I am doing a batch for which there is no template available, I just head back to my notes for previous batches of the same bean/blend and attempt to replicate the original roast data, and ultimately create a new Template to use in the future. These, of course, can be manipulated based on taste tests to address any perceived roast shortcomings - Nothing new really...
    Hi Mal
    This is an interesting point you make, which I've been pondering the last little while. What basic taste parameters do you use to decide when to adjust a roast profile? Or do you take a new SO bean, just trial 4-5 different 'templates', see which works? So far I have some of basic adjustment ie if it is sour, stretch out the time to first crack (as seen in this thread), if is oily & bitter drop a bit earlier etc. But I wonder if there are any 'markers' pro-roasters use to fine tune a roast for a bean…?

    Just FYI I also tried a roast today based on one of your suggested profiles from an old post (couldn't find it again if I tried!) which had a 10-12deg ramp for 5mins, then 16-18deg ramp from there to first crack. I was never able to achieve that slow start on my old setup - it always raced away, but the Bosch setup now lets me do it - so I thought - what the hey! We'll see how it goes in a week or so :-)

    So thanks in advance!

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    Quote Originally Posted by Yelta View Post
    Reporting back.
    So, after 3 days, how was it in the cup? prepared as a long black, quite drinkable, loads of crema, a little on the thin/watery side for my taste, there is no question, I tend to prefer my roasts on the dark side, perhaps it will improve over the next few days.
    I'll drink this lot without complaint, however my next batch will certainly stay in the roaster a little longer.
    Hey Yelta
    Will be interesting to see how it progresses as it ages.

    Just a thought - I found early on with my Bosch setup that a single fixed temp always gave a reducing curve profile - and a bit of a flat taste, just like you mentioned. Not bad - just nothing extraordinary.
    I found that as soon as I started ramping the temp input (giving a flatter rise on the profile) - all the lights came on in the cup!
    So for my early successful ball park profile with the Bosch, I'd do a basic gentle warm for 2mins on 180 (all fan 3), 350 up until 130(DMM), then 400 until 160, then 450 up till first crack. In the cup, this ramping input seemed to add a lot more interest, plus a lot of additional body and some more 'cocoa' - even when roasted quite light - just before second crack. Before this, non of my roasts were really cutting through soy - but we finally got some taste! Not bad as doppios - but still quite light & aromatic, rather than thick and gloopy.

    I also think I had an aha moment about roast depth a few weeks ago, when I roasted darker than usual (about CS9-10) which was too far for the beans I was using (making them oily and bitter) but still had an over-riding sour, under-roasted taste! Doh! So there's more going on that just roasting darker… although some beans, like the mad mexicans, seem to enjoy that zone and handle it quite well. Must be all the tanning oil & tequilas!

    So I'm working lots on the zone before second crack - I think this is where a lot of the taste is to be had :-)

    Happy roasting over in the hotlands!

    Matt

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    Quote Originally Posted by DesigningByCoffee View Post
    Hi Mal
    This is an interesting point you make, which I've been pondering the last little while. What basic taste parameters do you use to decide when to adjust a roast profile? Or do you take a new SO bean, just trial 4-5 different 'templates', see which works? So far I have some of basic adjustment ie if it is sour, stretch out the time to first crack (as seen in this thread), if is oily & bitter drop a bit earlier etc. But I wonder if there are any 'markers' pro-roasters use to fine tune a roast for a bean…?
    More or less Matt..

    I have a number of profiles that I use to start out with a previously untried bean variety. These are based on the bean origins and give me a starting point. I then roast at least three profiles starting with one that takes the batch through to the start of 2nd-Crack, the next batch goes about 20 seconds into 2nd-Crack, with the last stopped about 20 seconds before 2nd. The profile up to the start of Rolling 1st-Crack is the same for each batch as is the profile between Cracks - Only the timing around 2nd-Crack that changes.

    After giving the batches a couple of days to degas and flavour development to happen, I then just run a series of simple taste tests using Long Blacks. Which ever of the batches tastes best to me, I then concentrate on subsequent batches based on this profile and play around with it until I'm really happy that I'm getting the best I can from the bean. This is where all the fun is of course... Stretching or compressing the ramp up to 1st-Crack, the transition zone from about 180C until the start of 1st-Crack, post 1st-Crack ramp duration and rate, whether I actually head into 2nd-Crack and if I do, how far along do I go; into Rolling 2nd-Crack or allow the lazy initial cracks to continue for 'x' amount of time... And the list goes on and on...

    With regard to "Markers" that the Pro's may use. No doubt there are but I bet that's where the Sample Roasting comes in coupled with Cupping Sessions. Each Pro probably has their own routine and method to suit the way they do things; coffee roasting seems to be such a personal expression when you come right down to it. Would be interesting though to attend some sample roasting and cupping sessions, would be a great opportunity to learn.

    Quote Originally Posted by DesigningByCoffee View Post
    Just FYI I also tried a roast today based on one of your suggested profiles from an old post (couldn't find it again if I tried!) which had a 10-12deg ramp for 5mins, then 16-18deg ramp from there to first crack. I was never able to achieve that slow start on my old setup - it always raced away, but the Bosch setup now lets me do it - so I thought - what the hey! We'll see how it goes in a week or so :-)

    So thanks in advance!
    Wow! That does sound like an old one... Seems spring from when I was reading a lot about how Willem Boot likes to roast. Will be interesting to hear your thoughts once you've had a chance to try it.

    All the best mate,
    Mal.

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    Life-long Learner DesigningByCoffee's Avatar
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    Thanks Mal
    That's a really helpful overview.
    There are just so many variations it's hard to know where to start. Esp when the beans in the supply keep changing! You're almost better off to buy 20kg of one type of bean and work it till it's nailed! I suppose this is where commercial roasters have a faster learning curve - if you do roasts every day (rather than every week) it would certainly speed up the cupping opportunities (and increase the failed batch size too :-)

    I'll certainly be interested too to see how that slower start/harder ramp works out - it was certainly a vigorous first crack. I've been pretty sold through personal experience on the s-curve input temp profile - this just really ups the intensity of the curve I've been following.
    Let you know how it goes…

    Enjoy the storms!
    Matt

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    Hi all
    Just a little update. Like the rest of the country we've been getting some warm ones, so a great chance to try some warm weather roasts!

    The findings?
    On my covered/insulated corretto with 350g greens, to achieve a consistent roast that matches my preferred profile, I simply need to drop the temp ramp leading to first crack by 10deg on the gun (so 7.5 deg inlet temp) for each 5 degree rise in ambient. Strangely, the settings after first crack remain about the same - maybe because temp by this stage is so much higher than amb anyway? So for example, to achieve the profile attached, the method is as follows:

    • So, for a cold weather roast (amb 10deg) the approx ramp looks like this:

    190 (gun) pre-warm for 3mins
    370 (gun) @ 3mins (DMM)
    420 (gun) @ 130 (DMM)
    470 (gun) @ 160 (DMM)
    Drop to 410 (gun) @ 195 (DMM) just before first crack, then 360 @ 210, maintain till drop.


    • For a warmer weather roast (amb 20deg) this ramp looks like this:

    170 (gun) pre-warm for 3mins
    350 (gun) @ 3mins (DMM)
    400 (gun) @ 130 (DMM)
    450 (gun) @ 160 (DMM)
    Drop to 410 (gun) @ 195 (DMM) just before first crack, then 360 @ 210, maintain till drop.


    • For a hot weather roast (amb 30deg) this ramp looks like this:

    150 (gun) pre-warm for 3mins
    330 (gun) @ 3mins (DMM)
    380 (gun) @ 130 (DMM)
    430 (gun) @ 160 (DMM)
    Drop to 410 (gun) @ 195 (DMM) just before first crack, then 360 @ 210, maintain till drop.


    Seems to work really consistently - and the results have returned to the cup :-).
    This would obviously need to be varied based on altitude & humidity, also bean mass - but the theory seems pretty solid.

    Happy hot-weather roasting all!

    Matt
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  28. #28
    Senior Member Yelta's Avatar
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    Quote Originally Posted by DesigningByCoffee View Post
    Hi all
    Just a little update. Like the rest of the country we've been getting some warm ones, so a great chance to try some warm weather roasts!

    The findings?
    On my covered/insulated corretto with 350g greens, to achieve a consistent roast that matches my preferred profile, I simply need to drop the temp ramp leading to first crack by 10deg on the gun (so 7.5 deg inlet temp) for each 5 degree rise in ambient. Strangely, the settings after first crack remain about the same - maybe because temp by this stage is so much higher than amb anyway? So for example, to achieve the profile attached, the method is as follows:

    • So, for a cold weather roast (amb 10deg) the approx ramp looks like this:

    190 (gun) pre-warm for 3mins
    370 (gun) @ 3mins (DMM)
    420 (gun) @ 130 (DMM)
    470 (gun) @ 160 (DMM)
    Drop to 410 (gun) @ 195 (DMM) just before first crack, then 360 @ 210, maintain till drop.


    • For a warmer weather roast (amb 20deg) this ramp looks like this:

    170 (gun) pre-warm for 3mins
    350 (gun) @ 3mins (DMM)
    400 (gun) @ 130 (DMM)
    450 (gun) @ 160 (DMM)
    Drop to 410 (gun) @ 195 (DMM) just before first crack, then 360 @ 210, maintain till drop.


    • For a hot weather roast (amb 30deg) this ramp looks like this:

    150 (gun) pre-warm for 3mins
    330 (gun) @ 3mins (DMM)
    380 (gun) @ 130 (DMM)
    430 (gun) @ 160 (DMM)
    Drop to 410 (gun) @ 195 (DMM) just before first crack, then 360 @ 210, maintain till drop.


    Seems to work really consistently - and the results have returned to the cup :-).
    This would obviously need to be varied based on altitude & humidity, also bean mass - but the theory seems pretty solid.

    Happy hot-weather roasting all!

    Matt
    Crikey Matt, all seems quite complex, regardless of season I start the beans @ ambient temp, similar heat gun settings every time (a bit warmer in winter, cooler in summer) let her run to FC (always happens @ 200c) approx 13 mins, if it seems to be getting there a bit fast I knock the HG back by 50c then let it run until finish, depending on the beans somewhere between 225 and 230c.

  29. #29
    Life-long Learner DesigningByCoffee's Avatar
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    Howdy Yelta
    Not too complex really - even if it looks it when presented like that :-)
    I just add or subtract 10deg to/from my gun input ramp as the ambient increases or decreases - and get an identical profile every time summer or winter. Repeatability is key!
    Matt

  30. #30
    Senior Member insomnispresso's Avatar
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    We need some graphs!! Just kidding

    Matt, why not also measure time? I think that's what lead to your initial "summer conundrum"

    Cheers
    Matt

  31. #31
    Senior Member Yelta's Avatar
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    Quote Originally Posted by DesigningByCoffee View Post
    Howdy Yelta
    Repeatability is key!
    Can't argue with that statement, as long as they're not repeated failures.

  32. #32
    Life-long Learner DesigningByCoffee's Avatar
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    Quote Originally Posted by insomnispresso View Post
    We need some graphs!! Just kidding

    Matt, why not also measure time? I think that's what lead to your initial "summer conundrum"

    Cheers
    Matt
    Your wish is my command!
    These graphs should answer your time question too - my initial issue was that with warmer weather, the time overall was reducing, giving sour roasts. Those input gun temp tables I posted before show how I deal with changes in ambient to get basically identical profiles (ie same curve, time etc). These profile are from an 18 degree day and a 28 degree (you can see the start temp difference). But after the prewarm they are basically identical.
    And the background 'ideal curve' shown is my 'repeated success' curve, Yelta. But I do agree - if you're going to repeat a roast, make it a goodie! And now I can repeat this profile in summer - the goodness is back in the cup!
    Cheers Matt

    BTW the Peru was a fraction fast (I broke my own rules!) - I should have dropped by the 10deg at all points… live and learn!
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  33. #33
    Senior Member insomnispresso's Avatar
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    Loved reading your roast notes

    So they are both good ones right? Is the second crack much earlier on in the bad one?

  34. #34
    Life-long Learner DesigningByCoffee's Avatar
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    Morning!
    No, they are both what I expect are good roasts (I'm about to crack the 'un-noted' columbian bag - so can't confirm yet! :-).
    Not a huge difference in the Columbian, but I could have slowed it a fraction more (see how it sits above the line) - which would have actually fitted it perfectly into my 'theory' - but I chickened out half way and kept the temp up a bit :-)

    Just as a comparison - here is the graph of one of my 'summer sour' roasts. As you can see - similar inputs gave the same shape profile - but first crack at 11-12 mins, not 13-14 - and the tasting results show my thoughts…
    Attached Images Attached Images
    Last edited by DesigningByCoffee; 6th December 2012 at 09:34 AM. Reason: Wrong Profile

  35. #35
    Life-long Learner DesigningByCoffee's Avatar
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    Quote Originally Posted by Dimal View Post

    Wow! That does sound like an old one... Seems spring from when I was reading a lot about how Willem Boot likes to roast. Will be interesting to hear your thoughts once you've had a chance to try it.

    All the best mate,
    Mal.
    Hi Mal
    Into that bag now - and interesting! Amazing aroma off the beans in the hopper & off the grinder. Tighter pour, but without bitterness. Less body overall, lovely light, floral cup - great doppio! Not sure whether it will cut through the soy that well yet… will update on that. I'm thinking that the slower ramp gives more body/cocoa… which seems to work better through the soy around here - but hope to be proved wrong!

    BTW did I say it smells amazing…? ;-)

    Here's the profile for reference…

    Matt
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  36. #36
    Life-long Learner DesigningByCoffee's Avatar
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    Update - as suspected, a beautifully aromatic cup, but didn't have the cajones to really punch through the Vitasoy. We'll see over the next couple of days if anyhting changes ;-)

  37. #37
    Senior Member insomnispresso's Avatar
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    Am I interpreting the graph correctly to understand the sour roast was dumped ~2 mins earlier than the two good ones?

    Did the audible second crack not actually start a few mins earlier than the second crack column?

  38. #38
    Life-long Learner DesigningByCoffee's Avatar
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    Quote Originally Posted by insomnispresso View Post
    Am I interpreting the graph correctly to understand the sour roast was dumped ~2 mins earlier than the two good ones?

    Did the audible second crack not actually start a few mins earlier than the second crack column?
    Certainly did :-)
    That grey second crack column is my ideal second crack timezone - therefore second crack came on 2mins early (as did first crack and everything else). But what's interesting is that the first crack-second crack time is basically the same length - therefore my hypothesis that most of my ambient temp (and therefore flavour) issues happen as a result of the time before first crack!
    Elementary, my dear Watson!
    Matt

  39. #39
    Senior Member insomnispresso's Avatar
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    Not sure and you can correct me but I think there might be around 60s diff in first crack-second crack duration (KJM vs Eth/Indo) but you're correct there are also differences earlier on which is interesting.

    One interesting data point is your dry (yellow) stage (assumed around 150c) is very different 7.5 vs 9ish. Could it have been the drying being too quick causing the issue? Hrmm..

  40. #40
    Life-long Learner DesigningByCoffee's Avatar
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    Quote Originally Posted by insomnispresso View Post
    Not sure and you can correct me but I think there might be around 60s diff in first crack-second crack duration (KJM vs Eth/Indo) but you're correct there are also differences earlier on which is interesting.

    One interesting data point is your dry (yellow) stage (assumed around 150c) is very different 7.5 vs 9ish. Could it have been the drying being too quick causing the issue? Hrmm..
    I think that's about right - I didn't mark the actual first crack crack point, but with both being 199 from memory, the difference was probably closer to 30secs (cracks came before the marked temp on KJM) and the Mocha dropped 10secs into giving just under 5mins for one and just over (and fairly loose hand drawn graphs :-)
    But I think it is the earlier stages that seem to play a large role in the flavour development - exactly where in the process I'm still not sure. I'll keep playing!

  41. #41
    Life-long Learner DesigningByCoffee's Avatar
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    Well, done plenty of pre-Christmas roasting, and it's now time to publish my results on the Summer Conundrum!
    There is a little temp adjustment required between first crack-second crack to maintain an even profile, but it is not as significant as in the main ramp to first crack. But having done 6-7 roasts in the last week in variable ambient temps, this following procedure seems to be gaining more consistent results. You'll notice the first crack-second crack temp adjustment is only required every 10deg of amb, not every 5deg.
    I've now added an ambient conversion table to my roast profile sheet, simply for my own reference - if it is useful for anyone else - please enjoy!
    Matt
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  42. #42
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    DBC, that is such a helpful chart - I want to graduate off the poppers because of the small quantities and was scratching my head with all the corretto information around. Your posts have been very detailed and thoughtful. I managed to get the Kenwood BM250 second hand and decided to buy the Bosch630. I can't afford the logger just yet with all the Christmas shopping but I am going to try and match your profile

    From your video, the height of the gun is just above the pan or the lid?

    Thanks again
    S

  43. #43
    Life-long Learner DesigningByCoffee's Avatar
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    Hi Somerset
    Glad all the downloading has been of some use!
    The lid pretty much sits right on the top of the pan - the tin can chimney is about 1inch high (depending on what version of the corretto that was!). It is also pretty well insulated, and the batch sizes were 350g.
    While my 'technique' in that chart for different ambient temps is pretty much set in stone for me now, I do know that others in different places have tried it with varied results - we have low humidity and high altitude which does play a part - Sydneysider found my temps were much higher than they required
    The hardest thing if you roast without a temp probe will be knowing when to change gun temps - as I work off the bean mass temp. In theory you could try looking at the profile and going by the times instead - be might be a little hit and miss, but if the time ends up too short - try the higher ambient settings next round
    However, give it a go, and write down the times when you hit first crack and second crack and any other notes - and work from there
    All the best. A well setup corretto will give you amazing results when you have a handle on it.
    And let us know how you get on!
    Cheers Matt

  44. #44
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    Hi DBC, this is my setup, had a great time experimenting with it. Found the HG to be excellent value in the temperature control since I have no DMM. Managed to use a deep fryer temperature probe as a rough indicator and I must say, your profile sheet is spot on with the timings. I'd say I had luck with 2 out of 4 roasts, found the yemen quite hard to roast as I couldn't hear the cracks and I had to fiddle with a roast due to the lid melting ha. All in all, had great fun and got a pic of the best roast, a Brazil. Taste and quantity was great, well worth the effort.

    Thanks for your help and have a good Christmas

    S
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  45. #45
    Life-long Learner DesigningByCoffee's Avatar
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    Seemed to be a worthy place for this updated post
    Over the past few years juggling hot summers and cold winters, what I have found is that in both summer conditions (30°+) and in winter conditions (10° and less) I have to slow down the ramp from TP to first crack when compared to my baseline corretto profile to achieve a similar result in the cup. Strange but true.
    Some practical examples - here are three profiles…

    The Bandit - roasted to baseline at approx baseline temp of 25° - great flavour (been roasting & enjoying this blend for a few years).

    20150110-The-Bandit-Mex-Yirg-25amb-750g.jpg

    The Bandit - roasted approx to baseline at 11° ambient - overall sour and thin.

    20150509-TheBandit-450Pan-300Yirg-11amb.jpg

    The Bandit - roasted much slower compared to baseline at 8° (and cupping today ) - great flavour I've come to expect!

    20150713-Bandit-Yirg-Panama-750-8amb.jpg

    Whether this is DMM lag, actual input temperature of the gun or other humidity/environmental roasting quirks, I'm not sure. But it is a general issue cycling through each year - and the results are in the cup!


    Ahhhh - the quirks of roasting!

    Cheers Matt
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  46. #46
    Member dan110024's Avatar
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    Are you taking note of the bean temperature before loading them?

    (Just to preface this post... This is merely my opinion based on my knowledge of psychrometrics in the HVAC industry. I'm definitely no expert in the art and behaviour of roasting.)

    I have wondered about the relative humidity, when reading your posts regarding this before, but when the air is heated to such temperatures, the relative humidity would drop so much that it would have a negligible effect on how the beans behave during a roast.

    Generally, more work is required to cool the air with a high relative humidity, as you have to remove the latent heat, too, but the amount of energy required to increase the temperature shouldn't change regardless of the relative humidity. That leaves just the sensible heat difference, which is only 10-20 degrees difference, which is easily achievable by tweaking the gun temperature.

    I don't know how the electronics of the DMM could lag in any noticeable way to have such drastic changes to the roast.

    It's definitely an odd issue. Will be interesting to experience it myself through my first summer.
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  47. #47
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    For what it's worth, I found a psychrometric chart that goes up to 150°C.

    Let's say that we have an ambient of 11°C with a relative humidity of 60%. At 120°C, in the middle of the drying stage, we'll have a relative humidity of roughly 1%.

    If we look at a temperature of 80°C, pre-drying stage, with the same conditions, we'll have a relative humidity of roughly 2%.

    Regardless of what the relative humidity is at ambient temperatures, it decreases to such a small amount at the temperatures we're dealing with that it would have little to no effect on anything that might be happening during the roast.

    I think I can confidently say that relative humidity can be ruled out as a possible cause to this phenomenon.
    Last edited by dan110024; 16th July 2015 at 08:30 PM.
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  48. #48
    Life-long Learner DesigningByCoffee's Avatar
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    Quote Originally Posted by dan110024 View Post
    Are you taking note of the bean temperature before loading them? …

    I don't know how the electronics of the DMM could lag in any noticeable way to have such drastic changes to the roast.

    It's definitely an odd issue. Will be interesting to experience it myself through my first summer.
    Hey Dan
    Yeah - beans are stored now at a relatively consistent temp in my office now, which has helped some.
    The DMM can read a little high/low in 'extreme' temps (loosing that work loosely - ie sub zero ) but I don't think this accounts for all it - it mainly changes small things like first crack coming on 1-2° earlier etc (which will impact a little in overall timing).
    Humidity is fairly stable out here. I know that some Sydney roasters have had a very different result using my settings - I'm sure humidity and altitude play more of a part then - but we sit about 50% - down there more towards 90%.

    FWIW, I think it is more holistic - a small corretto roaster, large ambient swings (-8° to 40° range) ambient temps impacting the gun, gun internal temps, green bean temps, DMM temps etc - they all contribute towards noticeable 'shift' in flavour throughout the year in Millthope … even when I can fairly well 'match' logged profiles exactly at any time of year through adjusting change temp/TP & ramp temps.

    So I adjust my baseline profile to account for the seasons. Strange but true!
    And what I'm seeing in the cup - if I roast slower in summer, baseline in Spring and Autumn, and then slower again in winter - the roasts seem more consistent!

    Cheers Matt
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  49. #49
    Mal Dimal's Avatar
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    Behmor Coffee Roaster
    With these sorts of variations, you have to remember that using the DMM/Data Logger/Thermocouple hardware that we do, the accuracy tolerance across a wide ambient temperature range will cause a certain amount of 'drift'. Can't be helped when using t/couples combined with simulated cold junction correction in the meter. Improved accuracy across a wide range of ambient conditions could be achieved with more stable measurement technology but I don't really think it's necessary. There are at least a couple of CSers who use RTD100/1000 for their remote temperature monitoring and that's great, but not essential...

    Mal.



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