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Thread: Help me smoothen out my roasts

  1. #1
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    Help me smoothen out my roasts

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hi All,

    Wondering if those with Correttos can offer some assistance with making my roast profiles look a little smoother. I can assure you Im not simply interested in the asthetics, but want a better cup.

    Im roasting generally in 400g batches and after reading plenty of threads on roast profiles, I know how I want things to go, but am struggling to get control of the heat.

    As a generic roast profile, Id ideally like to hold the temp around 100 until 5 minutes, then ramp up to hit FC at about 9:30 - 10:30, then 4-5 minutes later dump just on or prior to SC.

    What usually happens is that I dawdle along to FC at about 11-13 minutes, then race into SC. The gradient is bumpy and usually the temp drops after FC, which from plenty of reading, I know to be baaad.

    Im using a breville with a smallish bread pan, a basic model Ryobi HG mounted on a tripod for control of the height/temperature. I also have been playing with using a lid.

    Heres todays roast profile. Typically, the bumps are when Ive adjusted the height of the HG.


  2. #2
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    Re: Help me smoothen out my roasts

    Hi there
    That looks similar to what i was getting when i had issues with the agitation of my BM, it wasnt as strong as it was previously causing dips in the temp and ultimately a totally uneven roast with beens going from green/yellow/CS 10.

    I generally run at 500deg on the HG for about 7:30 and then drop back to 450 and drop back after FC so that the increase is 3deg/min or as close as i can get between FC and SC.

    Here is a profile since changing BMs and i find i can steepen the start of the roast to achieve 130deg at the 5:00m mark by getting the HG up to full temp before putting over the beans.

    A number of the more experienced members here suggest a slower rise between FC and SC than what i used to do, generally i get about 4 - 5 min between them if i keep the increase at around 3deg/m or so.

    Mal


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    Re: Help me smoothen out my roasts

    ACog,

    what temperature probe are you using and where is it in the bean mass?

    We did an experimental batch today with 300g instead of our normal 600g or 1kg batch sizes. The probe was only barely covered by the beans AFTER they had expanded (following first crack)... this meant that our graph was very messy (so much so that we didnt save it!). However, we got good times @ target temps and our heat adjustments were fairly conservative (ie. no "panic" ramps or stalls). The temp probe gave variable readings because it wasnt properly buried in the bean mass.

    So... Maybe your thermocouple needs to be buried in the beans more.

    On the other hand, you might benefit from upping your batch size. Obviously, this depends on your BM and such, but we find that the larger batch sizes are MUCH easier to control and that they give much more stable temps readings. I suspect each Corretto has an optimum batch size - too small and its hard to control, too large and you get scorching/tipping from needing too high a heat input.

    Cheers
    Stuart.

  4. #4
    Senior Member greenman's Avatar
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    Re: Help me smoothen out my roasts

    Ill back up what Stuart said, my usual batch size is 600g giving me lovely even roasts, dropping back to 300g makes the roasts a lot harder to handle because my probe is almost on the surface of the beans.
    It took a while and quite a few holes drilled in the bread pan to find the optimum position for my probe, initially my profiles were 15C cooler than other CSers profiles now I reach first crack at 195-200C and second around 218-221C.

  5. #5
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    Re: Help me smoothen out my roasts

    Quote Originally Posted by 323F3C32500 link=1242558441/1#1 date=1242559894
    That looks similar to what i was getting when i had issues with the agitation of my BM, it wasnt as strong as it was previously causing dips in the temp and ultimately a totally uneven roast with beens going from green/yellow/CS 10.
    Hey Mal, Ive been following your thread fairly closely as I noticed similarities in our problems. I dont think however that the bean agitation in my BM is an issue. I get even roasts, its just difficulty controlling the temperature. I still suspect that maybe the HG is not being consistent in the temp its outputting, but I havent proven that yet.

    Quote Originally Posted by 2324253122243722313E24500 link=1242558441/2#2 date=1242568586
    what temperature probe are you using and where is it in the bean mass?
    The default one that comes with the official CS thermocouple. Not the bead type. Its placed via a hole through the side of the BM, sitting less than a mm above the paddle. Generally 400grams covers it, but only just. I suspect that it might be reading part bean mass and part air temp.

    Quote Originally Posted by 2324253122243722313E24500 link=1242558441/2#2 date=1242568586
    On the other hand, you might benefit from upping your batch size.
    Youre probably right. The biggest limiting factor for me right now is that my bean cooler is completely useless. I have a bucket and a bathroom exhaust fan setup but honestly, I think I could cool the beans faster by blowing on them. 400g takes about 4-5 minutes to cool.

    Quote Originally Posted by 372235353E3D313E500 link=1242558441/3#3 date=1242597160
    initially my profiles were 15C cooler than other CSers profiles now I reach first crack at 195-200C and second around 218-221C. *
    Funny that, my FC is generally around 210-215.

    Thanks all, Ill try a larger batch...but what to do about the cooling...

  6. #6
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    Re: Help me smoothen out my roasts

    Mmmm...

    If you look at your graph it is bumpy to FC BUT not after.
    The beans increase in size during FC. This then covers the probe properly?

    I can my temp straight as a die with a 300g green load. The probe is about 5mm above the bottom of the pan, fully in the beans at all times.

    Looks to me that you are reading both the air and bean mass temp. Increasing the roast size may smooth out the reading, not the actual bean temp.

    The bean cooler I have will cool the beans (300g) to room temp in about 1 - 1.5 mins. Have you tried a flat sifting pan?

  7. #7
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    Re: Help me smoothen out my roasts

    Quote Originally Posted by 6C6F7D7D796F770E0 link=1242558441/5#5 date=1242603382
    The bean cooler I have will cool the beans (300g) to room temp in about 1 - 1.5 mins. Have you tried a flat sifting pan?
    a few things Id like to do to improve my cooling is a) get rid of the useless exhaust fan and perhaps get a vacuum cleaner or 3 and b) get a metal sieve as it sounds like having a flat base rather than the curve that a colander gives is better and c) increase the diameter of the whole unit, so a bigger bucket and matching sieve.

  8. #8
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    Re: Help me smoothen out my roasts

    Quote Originally Posted by 72707C74747A7D60130 link=1242558441/6#6 date=1242604074
    a few things Id like to do to improve my cooling is a) get rid of the useless exhaust fan and perhaps get a vacuum cleaner or 3 and b) get a metal sieve as it sounds like having a flat base rather than the curve that a colander gives is better and c) increase the diameter of the whole unit, so a bigger bucket and matching sieve.
    I use a 20L bucket, a fan and a flat sifting pan.
    I tried a vac with this set up thinking it would be faster, made no difference. Although I am using a server fan (120watt).

    I think (havent done any experiments) that for a flat large diameter sieve a vac wont make a difference. For a small diameter can/colander it may. My thinking is that the vac is fast flow/low volume and the fan is low flow/high volume.

    My sift came in a set of 2. The hole are too large on one of them, half the beans drop through. You are more then welcome to have it, just put some steel fly screen or finer mesh on it.

  9. #9
    Sleep is overrated Thundergod's Avatar
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    Re: Help me smoothen out my roasts

    I probably fluked the position of my probe in that my temps read around those expected.
    The probe is towards the bottom of the bean mass (600g green) but even so, if I move my HG, which normally is aas far from the probe as possible, the readings will increase.

    I havent done a 300g roast for quite some time but did find that a 700g roast through me off a little.

    4 minutes to cool 400g shows poor performance of the cooler.

    Ive tried bucket/colander/vac
    Bucket/sieve/vac
    and recently installed a vac motor into the bucket so have
    Bucket/sieve/vac motor

    All work well in cooling the beans in about a minute.

    I think a flat bottomed sieve makes a fair difference.
    In my popper roasting days I cooled in a hand held flour sifter powered by the vac.
    The suction clumped the beans together too tightly for proper cooling.
    The larger surface area of the flat bottomed sieve mostly eliminates this problem even with my now larger batches.


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    Re: Help me smoothen out my roasts

    Quote Originally Posted by 4C706D767C7D6A7F777C180 link=1242558441/8#8 date=1242611283
    I havent done a 300g roast for quite some time but did find that a 700g roast through me off a little.
    Threw?

    Regards
    Acting Spelling Police Supt. ;)


    In other matters...

    This thread on our new cooler might be useful?

    We were using a hemispherical mesh colander and found that our cooling time halved when we switched to a flat mesh sieve. With our powerful fan, we can cool 1kg in about a minute. We used to have a 20L bucket with a bathroom-type fan (40W, I think) and it was underpowered and unimpressive, but would still cool the beans adequately. Buckets are free from McDonalds (theyll even fill it with spent coffee grounds for your garden!), bathroom fans are $15 from hardware stores... although our S/S fan only cost $20 so its worth looking around. Also, half a square metre of metal (not fibreglass) mesh will cost <$5 and you could fashion something from that.


    Regarding optimum batch sizes... It suddenly struck me that it would be worth cupping different batch sizes of the same bean using the same profile. Larger batch size might give you better recorded temps, but it wont necessarily give you a better heat profile INSIDE the bean (if that makes sense). ie. theres no sense in smoothening our graphs if what were really measuring is something other than bean temp. Just a thought.

    Cheers
    Stuart.

  11. #11
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    Re: Help me smoothen out my roasts

    Quote Originally Posted by 6C6B6A7E6D6B786D7E716B1F0 link=1242558441/9#9 date=1242614988
    Threw?

    Regards
    Acting Spelling Police Supt.
    Thanks.
    My excuse though is that I have a new PC crowded onto my desk top and am juggling the keyboard.
    The distraction of not dropping it probably threw out my inbuilt (brain) spellchecker. *;)

  12. #12
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    Re: Help me smoothen out my roasts

    Behmor Coffee Roaster
    I still suspect that maybe the HG is not being consistent in the temp its outputting, but I havent proven that yet.
    I would be surprised if this was the case, as we used to have that basic ryobi HG. It died, so when we took it back, we paid a little extra and got the variable temp one. Last night we did a 1kg roast and misjudged the starting temperature, but it meant that we got a FC at about 11mins without adjusting the temperature once. As this produced a perfectly smooth graph I reckon that its outputting the same temperature constantly.

    I agree with everybody else in saying that the bean temperature is probably more stable then your graph is showing. That is unless you are doing big adjustments in your heat gun height every minute or two :-)



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