Results 1 to 17 of 17

Thread: general roasting bean temp question

  1. #1
    Senior Member
    Join Date
    Jun 2008
    Posts
    1,520

    general roasting bean temp question

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Hey gang i had 2 failed roasts last week using my BM and heat gun (1600w 2 speed) using about a 500g batch

    1. Sumatra Panjang Mandheling
    tastes sour, i think it was not roasted enough i pulled on 1st SCs. I dont know what went wrong, its just rubbish tasting. Very sad as i have been getting good roasts out of it and have bought some more want to improve on this one so i can have a standard SO i like.

    2. Brazil pulped natural, actually 2kg (4 roasts) of the bag has been roasted badly? *I cant seem to get this one into tasting any good, i have about 500g left and dont know what to do with it. thinking of pulling it before SC as it seems very bitter (?) at anything into SC

    One issue i have found is my temp does not seem to go over 200, i discovered my TC is out a but and have adjusted for the variance but still i dont think i would hit anything over 205 (max) on any roasts

    CAN 2nd crack be hit under 200, do i need to push it higher?
    i leave the BM open on top, should I partially cover to retain some heat? but will this bring on cracks faster?
    i normally get FC in around 10-12 mins and SC 17-20 depending on what i am aiming for (experimenting)

    next roast is Et Gambella but will read some posts on it for ideas...

    anyone got any thoughts on my problems please
    Leeham

  2. #2
    Senior Member
    Join Date
    Oct 2008
    Posts
    505

    Re: general roasting bean temp question

    On my Corretto first crack is around 210C. Second crack around 230C.

    In most posts I have seen people are getting first crack at 205 and second at 220+.

    I dont think you are getting a high enough temp.

    A lid will help but it comes with its own issues, roasts can be smoky if you arent careful.

    Try lowering the height of you heat gun or lowering the batch load.

    Are you able to post any pictures of your setup?

  3. #3
    Senior Member
    Join Date
    Jan 2008
    Location
    Brisbane, Queensland, Australia, Australia
    Posts
    1,756

    Re: general roasting bean temp question

    DMM temp readings are relative, have you tested ya DMM in just off boiling water for 100C and a glass of icy slush for 0C? this may give you some indication if your on par, as for SC.......ive never seen it below 210 personally, but there are a lot more experienced ppl around here to offer advice...

    my 2 cents

    cheers
    warren

  4. #4
    Senior Member
    Join Date
    Nov 2006
    Posts
    1,077

    Re: general roasting bean temp question

    FC for me is generally around 205deg and SC around 225deg give or take a few deg either side.
    I partially cover the bowl with wood which makes it so that the HG can run at a lower temp.
    i use a 2000W Bosch with digital output and start at 550deg and then drop back to 500 at the 5 min mark, approx 130deg and then adjust so i get to 205deg at about the 11min mark.
    hope that helps
    Mal

  5. #5
    Mal Dimal's Avatar
    Join Date
    Oct 2004
    Location
    Warwick, QLD
    Posts
    16,968

    Re: general roasting bean temp question

    Definitely sounds like a shortage of MJoules issue to me... ;)

    Id try the "lid" option first mate as this can be very effective and as mentioned above, if you enclose too much of the top of the BM Pan, you may end up with slightly smoky flavoured roasts. Ive found with my setup though, when using a 1,600W heatgun, I only needed to cover slightly over half of the top of the bread-pan for batch sizes approaching 800g so you should easily be able to roast 500g batches.

    Just need to closely monitor the temperature of the bean mass more closely than usual until you get a handle on the new characteristics of the combination. All the best.... :)

    Mal.

  6. #6
    Senior Member
    Join Date
    Jun 2008
    Posts
    1,520

    Re: general roasting bean temp question

    old pic have put the original top back on the BM where the PID is

    i normally move the HG in a bit lower and over the middle to ramp up the heat , then lift it back up a little to slow it after FC a bit

    i use a omron PID and a jaycar probe, after discussing with BJeck14 *I checked the probe in boiling water, i was reading 6 deg low *:-?, *i have adjusted the PID to compensate for the error, but i know that it still would not have gone more than 205 based on past roasts.

    will roast a few more smaller batches to see if its any diff

    but i am sure i am not seeing +220

    any thoughts on a good way to test the probe at higher temp, was thinking of heating some olive oil?
    that red dig thermometer is good to 200 and i have another pid and TC bead

    thanks for the input

    Leeham

    PS, put some of the brazil through my 6900 this arvo, was not to bad... nothing fantastic but may have improved with a bit more rest as its at day 10 now,
    the brugnetti is in the shed for a de-scale / makeover

  7. #7
    Mal Dimal's Avatar
    Join Date
    Oct 2004
    Location
    Warwick, QLD
    Posts
    16,968

    Re: general roasting bean temp question

    Quote Originally Posted by 4549404D4D44280 link=1258510991/5#5 date=1258540320
    any thoughts on a good way to test the probe at higher temp, was thinking of heating some olive oil?
    that red dig thermometer is good to 200 and i have another pid and TC bead
    Youd need to have access to a second probe/DMM and preferably one that has been calibrated to be accurate within the range of temperatures youre mainly interested in.

    Rather than use Olive Oil though, Castor Oil is a better medium to use and better again is any of the Hydraulic Oils available from most Fuel/Oil distribution centres. You then contain this within a small, steel, open topped tank/bath and have a means for suspending the probes over the tank at identical levels and equidistant from the sides of the tank.

    All the best... :)

    Mal.

  8. #8
    Senior Member
    Join Date
    Jan 2008
    Posts
    476

    Re: general roasting bean temp question

    Gday leeham.

    Are you certain you are reaching SC? Sounds different, distinct gap between cracks, colour, smoke, etc?

    If you are then the low reading is prob your setup and placement of the probe. My spread is FC at 195 and SC at 215. If you have a 15-2O deg gap then youre prob ok.

    Another issue be that some beans are getting to SC and others arent. A lid may help.

    sd

  9. #9
    Senior Member
    Join Date
    Jun 2008
    Posts
    1,520

    Re: general roasting bean temp question

    i am getting SC (well i am pretty sure) as have got the distinctive 1st C then RFC then a quite patch then i would pull on 1st signs of SC

    SC would come on after a 3 -5 min gap

    by the time i turn off HD and pull BM bin it is starting to SC a bit more.

    might have been a rouge batch on the Sumatra that i messed up, i have had a few more of the Brazil today out of my 6900 *and its OK.
    Now i am wondering if my Brugnetti has been messing with me?

    got to do some more batchs, problem is then i got to drink it and have been drinking a lot more the last few days...... *:D

    thanks again for the input,

  10. #10
    Senior Member flynnaus's Avatar
    Join Date
    May 2008
    Location
    Sydney
    Posts
    4,116

    Re: general roasting bean temp question

    I have the same BM model as Leeham (the Breville BM200) which I have been using for about 3 months and I am coming to the view that either the thermodynamics of it are crazy or I just havent got the hang of it yet.

    Ive observed some behaviour such as lowering the HG height causing the temperature to drop??? *

    Switching to a probe type TC, which is inserted into the bottom right corner of the breadpan, has helped with getting a *more consistent reading (plus I dont have to remember to withdraw it before removing the pan for dumping - so far *8-)).

    I am using a Bosch 2kW variable HG and I have better control over the temp if i use the HG fan and temp control buttons to adjust the temp rather than trying to adjust the height. The HG isnt pointed directly over the centre of the pan - I have it offset to blow more to the left side which (I think) might improve the airflow.

    I think Im starting to get the hang of it but Im still considering trying a different BM with a rectangular rather than square pan.

    See my most recent roast profile here

  11. #11
    Senior Member
    Join Date
    Jan 2007
    Posts
    541

    Re: general roasting bean temp question

    Leeham

    My temperature readings are "low" but always repeatable.
    Depending on bean, FC = 188 - 200C, SC 200 - 212C
    The tip of my probe extends only about 12mm into the bean mass, so the majority the probes shaft is not under the guns heat.
    I believe the rest of the shaft is losing some heat by convection.

    Your times generally look ok,
    Some beans may benefit from even faster roasts eg FC @ 10min.
    Generally, I find Brazils pretty strong and dark tasting [lots of caramalizing going on] so I prefer to keep short roasting times on these and pull at or just shy of SC.
    [I havent tried the pulped natural though]

    How long are you resting the beans?
    Very generally speaking, the Indos and Africans need longer rests, I usually hit the bag at the 8 day mark, peak = 10 -12 days

    Do your roasts look even? what colour are they, any chance of some roast photos?

    How are you brewing? How do you know your brew temp is OK?
    If you brewed with some CS Brown [or other great coffee] are you happy with the results

  12. #12
    Senior Member
    Join Date
    Jun 2008
    Posts
    1,520

    Re: general roasting bean temp question

    @ flynn Aus
    i am using the jaycar probe inserted from left 15mm above base of pan, and always have roast batch above probe to try to get temp from bean mass.
    HG is an old one i had in the toolbox but seems to roast ok, i have found sometimes moving it over the middle has increased temp ramp up, to the side helps get the chaff moving up and out
    I have not roasted a lot, 20 odd batches, have had some of what i considered good coffee, but the Brazil has stumped me...

    i just dont seem to get into the 200+, but that might change with adjusted and retested PID etc.

    @Reubster
    those Brazils i feel have been wasted..... but thats the learning curve of home roasting *:)
    try to rest 5 days then drink after that, i have been trying to increase frequency of roasting to give a bit longer rest (8 days)
    roast are fairly even, a few rouge ones and the odd tipping and pitting here and there
    I have a *Brugentti HX commercial 1 group, have been checking brew temp with PID (its not PID controlled) *but now think with possible incorrect temp reading causing some issues...
    also a SB 6900 (spare machine)

    thanks for the input again :), think i just need to keep at it.


    Be good to go over to Alchemy next week and talk with the experts :)
    I have sampled the coffee there before and I LIKE IT *!! *;D

  13. #13
    A_M
    A_M is offline
    Guest
    Join Date
    Mar 2006
    Posts
    6,381

    Re: general roasting bean temp question

    Always remember that temp sensors etc have different specks as well as the equipment that you plug into.....

    Two sensors of teh same type can give different readings and it can be significant at some points.

    1: Do an ice point check.. 20% water and 80% ice = Slush = Approx 0C

    2: Boiling water = Approx 100C

    Now those that are anal will say that depending on you position above sea level and teh quality of the water etc the above is not 100% Accurate.. They are correct; but for our purposes and requirements, it is about consistency and the values are an indicator only...

    You values for 1 and 2 above will give you an Indication of the performance of your probe and meter (Combined).

    My work unit is calibrated by a NATA lab and offsets applied.. Thus the values I get are quite close... AND liner...

    The probe and meter I got from BeanBay (Sorry Andy) are not in the same league ($$$) or same quality.

    Some recent testing quickly demonstrated that the METER was quite touchy at some points and further testing cleared the temp probe from being teh cause. Went so far as to attempt a calibration of teh said meter and to adjust the linearity offset ... But the adjustment pots are quite coarse and the impedance of the board and cct was such that stray leakage caused any number of false readings....

    Hence when I use it... The issue is consistency on my system...

    Not to compare 205C with 210C from another user....

  14. #14
    Senior Member
    Join Date
    Feb 2009
    Location
    Melbourne
    Posts
    275

    Re: general roasting bean temp question

    Hi Anger,
    Quote Originally Posted by 426D6466714E626D6264666E666D77030 link=1258510991/12#12 date=1258602024
    Boiling water = Approx 100C
    Now those that are anal will say that depending on you position above sea level and teh quality of the water etc the above is not 100% Accurate..They are correct; but for our purposes and requirements,it is about consistency and the values are an indicator only...
    I knew you were right, but I thought: "But how right"
    so Google revealed the whole truth but in the language of my youth,
    good enough for me (aah those were the days just how god made the earth) with Altitude in feet, mm of Hg in inches and Temp recorded in Fen code. So who more anal than I would like to convert each value into modern man speak?

    Lindsay
    Just trying to help

    TABLE *1
    Changes in Standard Temperature and Pressure (in Hg) as a Function of Altitude
    A=Altitude (ft.)
    P=Pressure(in. Hg)
    B=Boiling pt.( F)
    A * * * * * * * P * * * * * * *B
    -500 30.466 212.9
    0 29.921 212.0
    500 29.384 211.1
    1000 28.855 210.2
    2000 27.821 208.4
    2500 27.315 207.5
    3000 26.817 206.6
    3500 26.326 205.7
    4000 25.842 204.8
    4500 25.365 203.9
    5000 24.896 203.0
    5500 24.434 202.0
    6000 23.978 201.1
    6500 23.530 200.2
    7000 23.088 199.3
    7500 22.653 198.3
    8000 22.225 197.4

    TABLE *2
    Boiling Point as a Function of Barometric Pressure
    P=Pressure(in. Hg)
    A=actual Boiling pt. ( F)
    C= change in Boiling pt.[added or reduced]( F)

    P * * * * * * * A * * * * * * *C
    28.0 208.75 -3.25
    28.2 209.10 -2.90
    28.4 209.44 -2.56
    28.6 209.79 -2.21
    28.8 210.13 -1.87
    29.0 210.47 -1.53
    29.2 210.81 -1.19
    29.4 211.15 -0.85
    29.6 211.48 -0.52
    29.8 211.81 -0.19
    29.921 212.00 0.00
    30.0 212.14 0.14
    30.2 212.46 0.46
    30.4 212.79 0.79
    30.6 213.11 1.11
    30.8 213.43 1.43
    31.0 213.75 1.75

  15. #15
    Senior Member
    Join Date
    Feb 2009
    Location
    Melbourne
    Posts
    275

    Re: general roasting bean temp question

    Hi Leeham and Steve,

    I dont hold myself up as a Corretto roaster, but a pseudo Zen master/slave of the Corretto, if you can picture my detached unverifiable assumptions (now is that confidence inspiring? good now we are all focused on the same plane of scepticism).

    In spite of all that I have thoughts/opinions that I am yet to change.

    Regarding your Corretto roasting:

    With our temp measurement we are largely measuring at a point, the hot air around the beans and the bean surface through a thick stainless steel sheath.
    The temperature we want to know is within the average bean and we want the beans to have as small standard deviation as possible.
    To achieve a reading approaching our point of interest clearly the probe should be placed as far from the heat guns blast as possible.
    It is also to the good if all beans are evenly and similarly treated.
    Im sure there is nothing new in these statements (just setting the scene). *

    Think about trying the heat gun vertically pointing down at one corner?
    I imagine the heat entering at that point and travelling with the help of the stirrer paddle and bean movement in a circular direction, perhaps dissipating and rising as it moves around until under the heat gun gets a new hot blast.
    There is little else to control the heat movement.
    In my first Corretto after a period I began using a two third cover wooden lid and reinstated the heating element under the control of a simmerstat.
    More recently I set up a new Corretto where I have attempted to extended this management of heat and the hot air from the heat gun.
    What I am suggesting is that management of the heat flow is important and should have serious micro consideration.

    I have had some roasting problems but it has become clear to me in each case the cause: faulty TC meter and human error x N (not mentioning any names) steps are being taken as much as possible.

    I do not know if my thoughts are close to a reality or not, but my mind insists on coming up with models to explain my observations, I can be shut up but so far my mind cant be stopped, slowed yes.

    I suggest you sit over your Correttos with a cold one or coffee* and Zen them, take your time (probably multiple *).

    If this all sounds like rubbish give me one more chance and check out my Corretto post and see if a logic is apparent to you. I have thought a heat path and then leave it to the paddle to move each bean through it again and again. Well it seemed like sense to me.
    http://coffeesnobs.com.au/YaBB.pl?num=1255005839

    Kind Regards
    Lindsay


  16. #16
    Senior Member
    Join Date
    Jun 2008
    Posts
    1,520

    Re: general roasting bean temp question

    well to follow up on this i tested all my temp reading devices, and discovered the PID i was using was reading incorrect due to user error (ME) i had it on the wrong setting for K type probes thus the PID did not translate the info it was getting from the TC correctly

    after discovering this issue and reseting the PID onto the right setting i tested using heated vegetable oil / boiling water / ice slurry and it seems to be accurate to +-1deg compared to my other equipment up to 200. I can only assume it is reading fairly well up to (and over) 230deg etc.

    result on last two roasts +- 500G batches
    Ethipoian Limmu
    FC 193 10min RFC 197 10.30min
    SC 215 14 min pulled start of RSC 217 15min and dumped

    Natural E Gambella
    FC 196 12.30 min RFC 200 13min
    SC 210 16 min pulled onset of RSC 218 17 min

    Thanks for the input everyone

  17. #17
    Senior Member
    Join Date
    Oct 2008
    Posts
    488

    Re: general roasting bean temp question

    Behmor Coffee Roaster
    Great news Maheel - those roasts look a lot better. Sit it out a few days and you will have yourself some delicious coffee!



Similar Threads

  1. boiler temp question
    By FineGrind in forum Brewing Equipment - Pointy End ($1500-$3000)
    Replies: 6
    Last Post: 18th November 2012, 01:34 PM
  2. Boema single group temp question
    By jam in forum Brewing Equipment - Extreme Machines ($3000+)
    Replies: 9
    Last Post: 24th May 2010, 12:03 AM
  3. microfoam question - milk temp and consistency
    By petar in forum Milk Froth and Bubbles
    Replies: 17
    Last Post: 8th April 2010, 06:36 PM
  4. General question on Massaii AA and American Blend.
    By speleomike in forum General Coffee Related...
    Replies: 5
    Last Post: 31st December 2005, 01:55 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •