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Thread: De-gas differences

  1. #1
    Senior Member GregWormald's Avatar
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    De-gas differences

    Gene Cafe Coffee Roaster $850 - Free Beans Free Freight
    Gday all roasters.

    A couple of days ago I roasted 2 batches in the Gene Café--Sumatra Blue Lintong and Ethiopian Harrar Longberry. While they had slightly different profiles (nothing radical) they were roasted to the same level (CS-9-10). The Harrar appears to be de-gassing at least twice as much as the Sumatran and has been since the first couple of hours in the bag.

    Ive been squeezing out the CO2 from both bags and the differences in out gassing are continuing.

    Anybody else notice differences like this?

    Anybody have explanations?

    Greg

  2. #2
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    Re: De-gas differences

    I dont think ive ever really paid too much attention to it greg, its an interesting question though, and i certainly cant give any technical advice on why it would be different for the different beans, i would imagine the CO2 output levels would be influenced by a lot of things including all the processes from the origin of the tree right through to the level of roast, and even the climate in which they are degassing, the moisture level in the original raw product, etc etc.
    Just a quick one on a side note(i dont want to hijack the thread) do the valved bags seep(for lack of a better word)CO2 without pressure? as in will they bleed off CO2 before the bag is inflated, i would have thought so, are you seeing a visual inflation Greg or is it your sense of smell gauging the degas amounts?

    I know i havent helped........sorry :-[

    interesting topic though :)

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    Re: De-gas differences

    Quote Originally Posted by 6763455C5C5946515E300 link=1255608997/1#1 date=1255610944
    do the valved bags seep(for lack of a better word)CO2 without pressure? as in will they bleed off CO2 before the bag is inflated
    I wouldnt think so
    I would say that the valve needs a reasonable pressure to have it open up.
    You can test this by putting a detergent/water mix over the valve or immersing the bag in water and seeing how hard you have to press before air escapes.
    Without actually testing this I would think that the bag would have to be blown up fully before any air escapes
    Hence manually degassing a non valved bag would be just as effective, its just that a valved bag will let degassing continue even when the bag is fully inflated without manual intervention

  4. #4
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    Re: De-gas differences

    Well Ive never had one of my bags blow up that big, thats a lot of co2 to expel, if this is the case, then why do we pay extra for valves bags? :-?

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    Re: De-gas differences

    I still use them myself. (I bought some last beanbay)
    I like the strong opaque bags with a good zipseal and they are fairly cheap if you reuse them so the valve for me is just an extra.
    Would be interesting to hear others thoughts on this
    (maybe should start another thread?)

  6. #6
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    Re: De-gas differences

    Thinking about it a bit more...
    The valves are probably there for when the bags are heat sealed at the top and there is no other way to get the gas out

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    Re: De-gas differences

    Yeah thats possible too, ok Im putting it out there, if this is the case, and if were wrong(which I believe we are)please correct me, should we toss the valve? I personally believe they do seep, because you can smell the gas without opening it, eg when its been in a cupboard, or is this simply the zip seal leaking?

  8. #8
    Sleep is overrated Thundergod's Avatar
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    Re: De-gas differences

    I believe the ziplock is not always airtight and gets worse with wear.


  9. #9
    Senior Member GregWormald's Avatar
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    Re: De-gas differences

    Im sure of one thing only--there is a little seepage.

    Seepage because I can smell the beans sometimes, even when the bags are heat-sealed.

    Little because it takes quite a squeeze to get the gas out if the bag is still loose and floppy.

    BTW--today the Sumatra bag contains more gas than the Harrar. So the Harrar has gassed-out earlier and faster and it now appears the Sumatra is catching up. There is only a half-hour difference in the time of the roast so no joy there explaining anything.

    More of the mysteries of coffee. What a great hobby! :o

    Greg

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    Re: De-gas differences

    Did the underwater test and found that air only escaped under the pressure of squashing the bag.
    The surprising thing was that it came out of the ziplock first.
    This was tested using 2 older and 1 unused bag.
    If any gas is lost due to seepage (not higher pressure related) I doubt it would ever be enough to stop the bags inflating

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    Re: De-gas differences

    Dont forget that water will offer higher resistance against the air coming out. So This experiment may not give you a completely accurate idea of whats going on under normal atomspheric pressure.

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    Re: De-gas differences

    Quote Originally Posted by 73717D75757B7C61120 link=1255608997/10#10 date=1255690098
    Dont forget that water will offer higher resistance against the air coming out. So This experiment may not give you a completely accurate idea of whats going on under normal atomspheric pressure.
    I actually think that the pressure of the water on the bag (with the ziplock and valve at the top) would create much higher pressure inside the bag than normal atmospheric conditions

  13. #13
    Senior Member Luke_G's Avatar
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    Re: De-gas differences

    If your using a popper to roast then youll find that your coffee wont degas as much as if it were roasted in a drum roaster.

    The reason for this i would think comes from the fluid bed of air doing some of the degassing as its roasting possibly?

    I was using 1 way vavled bags when i roasted with my old popper and found that they never really blew up all that much so i swapped to sandwich bags and had no problems with them opening them selfs.

    I have noticed that the bags we get off tobys Estate are usually fully inflated within 24 hours of delivery which is usually 48 hours after roasting. It could actually be inflating quicker but they are packed pretty tightly in the box they get delivered in.

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    Re: De-gas differences

    Quote Originally Posted by 033A242A10084F0 link=1255608997/12#12 date=1255847281
    If your using a popper to roast then youll find that your coffee wont degas as much as if it were roasted in a drum roaster.

    The reason for this i would think comes from the fluid bed of air doing some of the degassing as its roasting possibly?

    I was using 1 way vavled bags when i roasted with my old popper and found that they never really blew up all that much so i swapped to sandwich bags and had no problems with them opening them selfs.

    I have noticed that the bags we get off tobys Estate are usually fully inflated within 24 hours of delivery which is usually 48 hours after roasting. It could actually be inflating quicker but they are packed pretty tightly in the box they get delivered in.
    Very interesting post luke,
    anyone got any ideas why the drum produces more gas than in the popper/corretto?

  15. #15
    Mal Dimal's Avatar
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    Re: De-gas differences

    Quote Originally Posted by 6E5749477D65220 link=1255608997/12#12 date=1255847281
    If your using a popper to roast then youll find that your coffee wont degas as much as if it were roasted in a drum roaster.
    Hmmm,

    Dont know about that Luke.... :-?

    My popper roasts, as well as my current Corretto ones, turn all my 1-Way Valve bags into little balloons after a few hours post-roast (with the bags impulse-sealed though). I think it has more to do with the beans being used, your roast profile and probably other factors as well.... ;)

    Mal.

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    Re: De-gas differences

    co2 gases effect the taste of coffee . if so how long does it take to release all the gasses

  17. #17
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    Re: De-gas differences

    Quote Originally Posted by 6378717E754F6471697C7F62100 link=1255608997/15#15 date=1255862413
    co2 gases effect the taste of coffee . if so how long does it take to release all the gasses
    Welcome mate..... [smiley=thumbsup.gif]

    It varies from bean to bean and the depth of the roast Bob but as a minimum, aim for 48 Hrs and stretch it out from there.

    The best way to find out what YOU prefer though, is to sample your roast batch(es) every day and observe the changes that you can taste and take particular note of when the batch tastes best to your palate. Were all a bit different in this regard so its no good me telling you to leave xxx beans rest for 5 days at a roast depth of 30 seconds into Second Crack(SC) as you might find that you prefer them to rest longer or shorter....

    A bit of suck and see Im afraid.... ;)

    Mal.

  18. #18
    Senior Member Luke_G's Avatar
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    Re: De-gas differences

    Quote Originally Posted by 7855515D503C0 link=1255608997/14#14 date=1255858370
    Dont know about that Luke....
    This is just my personale experience Mal :)

    I gave up on my popper when i got access to fresh roasted coffee from work..it just didnt compare anymore unfortunately :( Plus i never have to pay for my coffee anymore ;D

    I never went past the chimney and thermometre mod stage so my roasts were more observation than profiling.

    Got my Hottop coming though and im hoping ill be impressed with it..whilst i dont expect my results to be as high in quality as Tobys(obviously) im expecting a huge difference from the popper :)

  19. #19
    Mal Dimal's Avatar
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    Re: De-gas differences

    Quote Originally Posted by 477E606E544C0B0 link=1255608997/17#17 date=1256038182
    Got my Hottop coming though and im hoping ill be impressed with it..whilst i dont expect my results to be as high in quality as Tobys(obviously) im expecting a huge difference from the popper *:)
    I think you will be very pleasantly surprised by the quality of coffee that your new HotTop will produce (once you get a handle on squeezing out the best from her).
    Theres no reason why you couldnt try to emulate any roast of commercial origins that really excited your palate. The level of controllability offered by the HotTop will certainly allow for the potential of significantly improved outcomes over that of a popper Luke. No doubt about that.

    Im sure you will be very impressed and very happy with what you will produce 8-).... All the best mate and have fun ;D

    Mal.

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    Re: De-gas differences

    Quote Originally Posted by 4F7668665C44030 link=1255608997/17#17 date=1256038182

    Got my Hottop coming though and im hoping ill be impressed with it..whilst i dont expect my results to be as high in quality as Tobys(obviously) im expecting a huge difference from the popper *:)
    Dont be too pessimistic Luke... for sure, the person driving the machine certainly has a bigger impact on the result than the machine itself (just like with espresso) and as Mal said therell be a learning curve to climb; but Tobys Estate themselves actually use a Hottop B for sampling greens before committing to purchasing commercial size quantities. They said it did a better job than the other small home roasters theyd tried, and (and this blew me away) they said it was better even that the proper sample roaster they were using up to that point worth three times the price! Tobys testimonial is at http://www.thingscoffee.com.au/accessories/tobys-estate-testimonial.pdf in case you missed it.

    So if you like what they produce, theres no reason at all why you cant achieve the same result, all other things being equal. Your Hottops far from a toy!

  21. #21
    Senior Member redzone121's Avatar
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    Re: De-gas differences



    Popper = Skoda, Hottop = Rolls Royce

    IMO and experience with both popper and Hottop, shouldnt be used in the same sentence.
    You are in for a very pleasant surprise ;)
    I am sure Tobys are great but over this side of the Tasman I would have a Hottop and some of Andys green beans any day over some of our commercial roasters.

    Chris

  22. #22
    Senior Member Luke_G's Avatar
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    Re: De-gas differences

    Behmor Coffee Roaster
    Quote Originally Posted by 3423223C292823777477460 link=1255608997/20#20 date=1256116821
    Popper = Skoda, *Hottop = Rolls Royce
    Hahahahahaha i kinda like the Skoda and dislike the Rolls?! :-?

    Maybe we should say that the popper is a Hyundai & the Hottop is a Mercedes?

    Either way im not expecting anything other than for the Hottop to be deffinatively better than the popper.

    As for Tobys? We always get it no older than 5 days post roast so theres no complaints there :)




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