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The Summer Conundrum… advice sought!

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  • Dimal
    replied
    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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  • DesigningByCoffee
    replied
    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 1C 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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  • dan110024
    replied
    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; 16 July 2015, 09:30 PM.

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  • dan110024
    replied
    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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  • DesigningByCoffee
    replied
    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 1C 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).

    Click image for larger version

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

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

    Click image for larger version

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    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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  • somerset
    replied
    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
    Attached Files

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  • DesigningByCoffee
    replied
    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 1C and 2C 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

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  • somerset
    replied
    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

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  • DesigningByCoffee
    replied
    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 1C-2C to maintain an even profile, but it is not as significant as in the main ramp to 1C. 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 1c-2c 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
    Attached Files

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  • DesigningByCoffee
    replied
    Originally posted by insomnispresso View Post
    Not sure and you can correct me but I think there might be around 60s diff in 1C-2C 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 1C 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!

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  • insomnispresso
    replied
    Not sure and you can correct me but I think there might be around 60s diff in 1C-2C 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..

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  • DesigningByCoffee
    replied
    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 2C not actually start a few mins earlier than the 2C column?
    Certainly did :-)
    That grey 2C column is my ideal 2C timezone - therefore 2C came on 2mins early (as did 1C and everything else). But what's interesting is that the 1C-2C 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 1C!
    Elementary, my dear Watson!
    Matt

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  • insomnispresso
    replied
    Am I interpreting the graph correctly to understand the sour roast was dumped ~2 mins earlier than the two good ones?

    Did the audible 2C not actually start a few mins earlier than the 2C column?

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  • DesigningByCoffee
    replied
    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 ;-)

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  • DesigningByCoffee
    replied
    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
    Attached Files

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