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Thread: PNG Purosa organic A

  1. #1
    Senior Member Lovey's Avatar
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    PNG Purosa organic A

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Gday all, I had a go at roasting this on Sunday in my unmodified Aldi popper.
    It went into a rolling 1st crack about 2.14 and then it seemed to continue on into 2nd without a break. I ended up dumping the beans out at 4.50, by which time they were well and truly charcoal.
    Admittedly it was warm up here, about 20, and the Aldi has shown itself to be almost nuclear powered, (Ive since modified it to try and slow the heater down a bit.) *
    Is this bean particularly sensitive, or am I just a gumby? ;D
    Any tips would be appreciated.
    Steve.

  2. #2
    Mal Dimal's Avatar
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    Re: PNG Purosa organic A

    Hi Steve,

    Yeah, those Aldi Poppers seem to be turbo powered alright.

    Havent had a chance to try the Purosa yet but I have roasted other varieties from PNG, most recently the Sigri. In general, I have found the PNG beans to be pretty straight forward to roast and able to be taken deep into 2nd Crack while still retaining a significant proportion of the beans flavour profile... not into charcoal territory though ;).

    Id say the problem you have experienced is mainly due to the Aldi Popper itself more than anything to do with the bean. If you can reduce the output of the main heating element that will no doubt help quite a bit. Alternatively, you could ask a friendly local electrician to mod your Aldi by splitting the power supplies to the Heating Elements and the Blower Fan, then fitting a Solid State Fan Speed Controller (can be had from most Bunnings and similar stores quite cheaply) to the Blower Fans supply. This will give you the ability to increase the Blower Fans Output and tailor your Roast Profiles to a much greater degree and probably increase your roast batch size into the bargain. Depending on the electrical circuit configuration of the Aldi Popper, your sparky might have to obtain a small 240V/30V Transformer to supply the Fan. These are pretty cheap items too and wont add much to the expense. A really valuable tool to have on hand for a wide range of uses by the coffee geek, is the Digital Temperature Probe... usually an inexpensive Digital Multimeter that comes with its own K Type Thermocouple Probe. This little gadget will allow you to set up your roaster so that it roasts as near to perfection as you can get with a popper and that is definitely worth doing.

    For most of my roasts, I try to exceed a lower time limit of 9-10 minutes and generally not longer than 13-14 minutes for batches of between 100-120 grams. If you could try and stretch your roast times out to at least 8 minutes or so, you will definitely be able to taste the difference in the cup. Combined with adjusting the Roast Temperature or the Fan Output, you could try reducing your batch size by 5 grams at a time and see if this provides you with a more realistic roast time.

    Youll be there in no time Steve and then enjoy the wonderful aroma and flavour of home-roasted top quality coffee... nothing better ;D

  3. #3
    Senior Member robusto's Avatar
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    Re: PNG Purosa organic A

    Concur with Mal about the Aldi roaster. Although it was just $14, it packs quite a punch. Those times are pretty spot on, Lovey. I get chaff from 20 seconds, and first cracks from around 2.20. By 4-5 minutes its all over for a 60 gram roast.
    And thats been during the coldest Melbourne winter for some time, and outside temperatures well below 10C.
    Unless you go the way of major internal surgery as Mal suggests, no amount of cold, long extension leads etc will slow it down -- its too powerful for all that.
    Roasting
    Ethiopian beans in particular are difficult as these shun being evenly roasted at the best of times. By the time the paler beans turn brown, the others are charcoal. Its best to get most of the beans right and then throw out the pale ones.
    Needless to say, the plastic cover complete with butter dish are removed first.

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    Re: PNG Purosa organic A

    Have you added a chimney to help lengthen roast times and increase batch size?

  5. #5
    Senior Member Lovey's Avatar
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    Re: PNG Purosa organic A

    Gday all, Ive made a couple of mods to my turbo, nuclear powered, hyper-drive, warp speed popper.
    Its got a chimney, but this isnt really to extend the roast times, its more to stop the beans jumping out of the chute.
    Ive split the heater and fan circuits up. *As you said in a previous post Mal, they are not easy to do, having both 240VAC and 24VAC running around on the same PCB. *This was done with the assistance of our friendly local electrician, me. *;D
    I bought a 24VAC plugpack and tried to control its input with a light dimmer, but I got less voltage at the motor than before. *I then ditched the dimmer and just hooked the 24VAC to the input of the rectifier and got an extra 2 volts at the motor, which made the fan a fair bit quicker. I might try a 30V transformer as you suggested Mal.
    Ive just bought a thermocouple probe for my DMM to measure the temps, but this thing is so fast that theres no time to get a temp reading, whilst simultaneously working the stopwatch. ;)
    This electrical mod added 10 whole seconds to achieving 1st crack, but the ambient temp was 2 degs hotter when I tried a modified roast. *I guess Im just going to have to get up earlier in the morning. >:(
    If all else fails, theres always a HG I suppose.
    All the best,
    Steve.

  6. #6
    Mal Dimal's Avatar
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    Re: PNG Purosa organic A

    Hi again Steve,

    Yep, you need to go with a minimum 30V output Xfmr as the nominal voltage on the fans is usually 24V DC. When you rectify the 30V AC output, youll end up with about 27V DC, and if you use a 70V Electrolytic 1000[ch956]F Capacitor across the DC Output, youll be able to push that up to closer to 30V DC. Using a Solid State Ceiling Fan Controller (Light Dimmer Controllers are often unsuitable for magneto-reactive loads) on the Primary of the Xfmr, you should be able to realise a pretty wide range of control. 8-)

    With the Aldi Popper though, you might have go with a higher voltage 2ndry output to give you enough headroom to make the exercise worthwhile, something like a 36V-40V AC. Id say that the main problem though with the Aldi, is that the Heater Element is a little too boisterous and if you could find an economical way to reduce its output, youd just about have the problem solved. Short of making your own suitably rated Triac Controller, I dont know what else you might be able to do with this. Its a bit of a quandary alright :-?

    Cheers,
    Mal.

  7. #7
    Senior Member Lovey's Avatar
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    Update for PNG Purosa organic A

    Gday all,
    just a quick one to give an update on my efforts to roast this bean.
    I have now modified the nuclear powered Aldi popper so that it is much better behaved and its not like throwing the beans into the sun. ;D

    Original times at 15 deg * * * New times at 19 deg
    ambient temp. * * * * * * * * * *ambient temp.

    1st - *2.19 * * * * * * * * * * * * *12.28
    2nd - 3.00 * * * * * * * * * * * * *15.30
    Out - 3.15 * * * * * * * * * * * * *15.35

    Quite a marked difference in the times, to the point where its nearly verging on being in the popper for too long. :o

    A huge thankyou goes out to Mal for all your assistance and answering my numerous enquiries in relation to the technical side of things. :)

    Another question now in relation to roasting temps.
    Is there an ideal temp to roast at?
    Should the roasting temp be kept constant or should it be allowed to fluctuate?
    I was thinking of drilling a hole in the side of the popper and putting a thermocouple probe so that it reads roughly in the middle of where the beans are floating. *Is this the best place for it, or is there a better location?
    All the best,
    Steve.

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    Re: PNG Purosa organic A



    This is a roast profile of an Alpenrost.

    The roast temperature ramps up slowly as the beans gain heat. Im not sure in that profile where exactly 1st and 2nd cracks are. Beans will reach first crack at approximately 180C bean temp./205C with thermocouple. In the case of the Alpenrost, at around the 10 minute mark. Note there is 25C difference between the two. As long as you stick to one or the other, things should be ok. Infrared thermometers can take the bean surface temperature, and arent all that expensive. I picked up a pocket sized one from Dick Smith for 70 bucks, and it even has a laser pointer so you know what youre recording.

    Im sure there are more technical details that Im leaving out, so someone else can chime in if they see fit.

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    Re: PNG Purosa organic A

    It is very similar in profile at a glance with the Hottop although the hottop always starts at about 70C.

    Looks like a nice progressive profile.

    Grant

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    Re: PNG Purosa organic A

    Roast profile was just used as a visual example.

    If I took the time to plot a roast profile of a popper, I think things would look quite different.

    I think I need to have a static temperature sensor and a data logger. Or I could do it the old fashioned way.

    Maybe Ill do that the next time I roast.

  11. #11
    Mal Dimal's Avatar
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    Re: PNG Purosa organic A

    Hi All,

    First up, thanks for the kind words Lovey, glad to be of help. Those times youve got look pretty darn fine to me by the way. I suppose if you wanted to fine tune it a bit more, you could increase the temp setting a little to start off with, so that 1st Crack proper was happening at about the 8-9 minute mark, then reduce the heat a little and let the beans coast to 2nd Crack proper by the 14-15 minute mark. I dont think your overall roast time(s) are excessive though.

    The easiest way Ive found of recording the Roast Temp was to simply dangle a K Type Thermocouple into the bean mass and connect to a suitable DMM. This way, you should be able to record a reasonably stable Temp at the centre (or there-abouts) of the bean mass. Ive just made a support for the t/c by bending a coat-hanger so that it lightly clamps across the top of the chimney and then feed the t/c through this and into the roast chamber.
    On a 25 deg C ambient day, the Temps Ive been recording hover at around 160-170 deg C after 2-3 minutes, and reach 190-195 deg C at the start of 1st Crack proper and then slowly build up to a peak of 215-218 deg C by the time 2nd Crack proper has started. The time between 1st and 2nd varies a bit from bean type, RH, moisture content of the beans and probably a lot of other criteria. Ive never found it necessary to change much from this, except for one batch of beans that took about 50% longer than the "norm" because they were so hard.

    Hope this helps ;D,

    Mal.

  12. #12
    Senior Member robusto's Avatar
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    Re: PNG Purosa organic A

    Steve, that is a very significant change in temperature v time for the Aldi. What modification did you make apart from the initial separation of heating and fan circuits, may I ask?

    Regards, Robusto

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    Senior Member Lovey's Avatar
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    Re: PNG Purosa organic A

    Gday Robusto,
    The mods Ive made are in 2 parts, after splitting the fan and heater circuits, as youve mentioned.
    1. The fan motor is run through a separate transformer, with a ceiling fan controller on the primary side of the transformer. *This gives variable speed control.
    2. The heater is now run through a modified light dimmer switch, but Im about to construct a dedicated control circuit for this, with thanks to Mal.
    Hope this helps,
    Steve.

  14. #14
    Senior Member robusto's Avatar
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    Re: PNG Purosa organic A

    Thanks, Steve. Obviously the main thing, I would imagine, is to restrict the current to the heating element, while either keeping the fan speed the same or, slowed somewhat to give additional control. Is that what youve aimed for?

  15. #15
    Senior Member Lovey's Avatar
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    Re: PNG Purosa organic A

    Thanks, Steve. *Obviously *the main thing, I would imagine, is to restrict the current to the heating element, *while either keeping the fan speed the same or, slowed somewhat to give additional control. Is that what youve aimed for?
    Gday Robusto,
    in relation to the heater, the idea is indeed to restrict the current flowing through the heater coil, thus giving you less heat.
    The fan mod is to increase the air flow by increasing the voltage to the fan motor, up to a point of course when it will blow up ;)
    Once you have an increased air flow, you can increase the batch size for a given temperature, which wasnt an option for this popper before I modded the heater circuit. *I think its got something to do with the air fluid bed, but dont quote me on that. :-?
    Hope this helps,
    Steve.

  16. #16
    Senior Member robusto's Avatar
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    Re: PNG Purosa organic A

    Yes, thanks again Steve, that is most helpful. All I need now is the bravado to tear apart my Aldi and begin the surgery required. :-[


  17. #17
    Senior Member Lovey's Avatar
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    Re: PNG Purosa organic A

    Youll have fun with it Robusto, I know I did. ;)
    If you need circuit diagrams or any help with it, just PM me and Ill be happy to assist.
    Steve

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    Re: PNG Purosa organic A

    Any notes on the Purosa Organic yet? I had a go at it this week, after hanging out with Hazel De Los Reyes on monday.

    I slowed down my popper by sitting a fan right next to it, blowing cool air at it. This gave me more control over the roast, even with the tin can chimney (ie: I can now slow it down - my popper was almost as fast as the Aldi job).

    I didnt record roast profiles ... sorry!

    Following Hazels advice, I kept the roast from reaching 2nd crack - I stopped it when 1st crack had completed, probably a minute or two short of second crack (at a guess).

    Its now been rested for 3 days. The grinds smelt like peanuts and chocolate.

    I had a go at cupping - and this was roasted with brewing in a plunger in mind.

    The break smelt like licorice, dried apricot, peanut and chocolate (again!). The taste was all dark bitter chocolate, dried apricots and (you guessed it!) roasted peanuts. As the cup got cooler, more ashy, bitter and woody flavours started to dominate. There was only very slight acidity - all around the sides of my tongue, roof of my mouth, and entry to the throat.

    Ill be drinking it from a plunger all weekend, Ill let you know how it goes, both solo, with a bit of milk and (gasp!) even a smallish bit of sugar added.

  19. #19
    Senior Member Lovey's Avatar
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    Re: PNG Purosa organic A

    Gday all,
    Ive roasted up a couple of batches of these in the last few days and Im having a bit of trouble trying to pour it.
    Ive got the grinder set up at +7 over the 0 point, which is fine for stuff that Ive had before from a local roaster. *But with this bean, all I get is 10 second blonde gushers. >:( (Sounds a bit like a cheap xxxx flick) :o
    The beans are now 4 days old, Im using an Espro tamp (one variable in my dodgy routine out of play *;), Ive tried different dose sizes as the initial dose was too big and I couldnt lock the portafilter in, so I went a bit smaller. Ive tapped the portafilter on the bench to settle the grounds, Ive given it a gentle shake as well. The machine is nice and warm, all to no avail.

    The only things that are constant are:-
    - Thick blonde gushes from each spout, almost gassy looking,
    - The puck always breaks when it gets knocked out into the bin.
    Can anybody help me? ::)
    Thanks,
    Steve.

    P.S. I *hope that everyone has a merry and safe Christmas (or day of their choice) and a prosperous new year.

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    Re: PNG Purosa organic A

    Lovey,

    +7 seems a bit high to me for a Silvia/Rocky combo as I usually hover around 3-4 but the number on Rockys dont necessarily match as the true zero point can be different between machines. So you might try a finer grind. Gushing I have found usually means I need to try a finer grind . Im kinda having the same problem with some PNG Ramu / Brazilian Daterra blend where occassionally I will get a gusher (doesnt stop me drinking it though :)). I drop it down a notch and it fixes the problem.

    Cheers,

    Matt

  21. #21
    Mal Dimal's Avatar
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    Re: PNG Purosa organic A

    Good advice Matt,

    Ive noticed the same characteristic when using PNG Sigri too..... as you have done, just knocked the grind setting down a couple of notches and the resulting pour is as "sweet as"...

    Merry Xmas All,
    Mal.

  22. #22
    Senior Member Lovey's Avatar
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    Re: PNG Purosa organic A

    Behmor Coffee Roaster
    Thanks for the tips Matt and Mal,
    I took your advice and wound the grind right back to 10, which is 4 over the true 0 point. A fantastic couple of pours resulted. :)
    All the best for 2006,
    Steve.



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