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Mushrooms, Mycology and Psychedelics > Gourmet and Medicinal Mushrooms
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Cant get collapsed bags by end of pc cycle
    #25568482 -

Hi everyone,

I am having a lot of issues with contaminated grain bags I am trying to produce myself. I assume the problem is occurring because i am getting contaminated air inside my autoclave when I equalize the pressure to open it. I base this on the fact that I am inoculating stuff in front of a flow hood (so the inoculation process should not be an issue), and also on the fact that the bags are never fully collapsed by the end of the cycle (as if they were pulled inside by some kind of vacuum) as I see a lot of people are able to do in their pcs (that also happens in RRs videos). Furthermore, the contaminations are always on the top of the bags, so this not most probably not due to a too short sterilization cycle. Finally, to further corroborate my suspicion, I have been able to make 20 agar plates with zero contaminants, whereas I get about 80% contamination in my grains bags (I think this, again, indicates my flow hood is not the problem).

So I was wondering what I could do to make my bags fully collapsed at the end of the sterilization cycle. What I usually do is turn of the heat and just walk away, and them some 24 hours later i am able to open the valve to let air in. Should I vent the autoclave at the end of the cycle, and them close the valve to let it cool? Anybody has had this kind of issue?

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Re: Cant get collapsed bags by end of pc cycle [Re: vsoares]
    #25568700 -

How are you folding up your bags? How do you have them in the PC?  Are you running sleeves in them?  Give us some more details. 

Sounds like your getting inflation of the bag.  Happen more often with pre sealing them, or if you have too much space inside the PC.  Also try to get all the air out of your bags before you PC.

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Re: Cant get collapsed bags by end of pc cycle [Re: Tookitooki]
    #25568743 -

Sleeves are supposed to not be necessary and if anything they could prevent contraction of the bags. The bags should shrink if they kinda seal by having folds and something like a rope keeping it tight as a package (or weight on top). If they seal when they cool they can start sealing even better and as the pressure lowers the bags should contract.

It's gotta be the way you prepare the bags?


--------------------
My trade lists:
  • Fungi - Edible / Gourmet
  • Fungi - Medicinal/Insecticides/Bioluminescents
  • Fungi - Actives
  • Fungi - Old Exotic Spores (Actives)
  • Fungi - Misc Hunted Mushroom Spores
  • Plants
  • Other items - Supplies etc.


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    Re: Cant get collapsed bags by end of pc cycle [Re: Solipsis]
        #25568887 -

    I have tried folding the bags and laying them inside the Autoclave in every possible way known to man. I have also sterilized with full autoclave and 2/3 full autoclave. After posting I was thinking more about It, and i realize most folks use polypropilene bags, whereas i have been using high density polyethile bags. I will get some PP bags and run a new test to see if i get different results, thanks guys.

    Edited by vsoares (10/26/18 10:45 AM)

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    Re: Cant get collapsed bags by end of pc cycle [Re: vsoares]
        #25568934 -

    I try to open valve on pressure cooker when it drops to zero.
    If you cooker pulls a vacuum then best to just open at flow hood. If you can't do that wrap alcohol  soaked rag around valve to filter as you release vacuum.


    --------------------

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    Re: Cant get collapsed bags by end of pc cycle [Re: Quadman]
        #25569083 -

    I've run with and without sleeves.  With sleeves I never got ballooning of the bag, and it still pulled a vacuum.  When I don't run sleeves, sometimes the air can't find its way out very well and will inflate the bag and cause it to come in filled to, or if it can't unfold itself, it'll stretch out the plastic.


    https://www.shroomery.org/forums/showflat.php/Number/25367454

    Here's a recent thread from mush cult about the topic that might help.

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    Re: Cant get collapsed bags by end of pc cycle [Re: Tookitooki]
        #25569832 -

    So you are using an autoclave and not a PC. I just want to be clear on that. If you are using a PC then don't do anything to release pressure at all. Let them cool in the PC. The slow cooling will cause a vacuum on the bags and seal them.

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    Re: Cant get collapsed bags by end of pc cycle [Re: SHROOMSISAY01]
        #25574423 -

    I'd bet you seal the bag which is the problem.


    --------------------
    Stop talking about being enlighten. Crybabies, bitches, and people worried about ratings can never reach enlightenment!  NEVER!

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    Re: Cant get collapsed bags by end of pc cycle [Re: Tits on a bull]
        #25578134 -

    Pretty sure you would notice as they would inflate or even pop. Probably makes a mess either way.

    Not sure if the material of the bags is relevant, HDPE should not melt until above 120C and I figure the producer knows they are for autoclaving.
    However the filter patch in the bags must have the right pore size. If not that could explain why you get top contams.

    Do the bags really have to be collapsed? The only thing you clearly don't want is dirty air flowing back in as the bags cool. If there is plenty of air in there this air should just compress from cooling but if there is very little air in there the pressure could drop to the point of sucking in air.
    But if the bags are still folded by having used rope to wrap them, air cannot really pass properly so it seals and contracts causing a small vacuum / collapse.

    People use tyvek sleeves in the folds to try and filter this air. But not everyone agrees on it.

    I used to fold my bags differently but now fold it in a "loop" so that the opening of the bag is wrapped inside and I do use sleeves.

    If you take the bags out of the autoclave when warm and let them cool in open air and the amount of air in there and pressure etc cause air to get sucked in that could be a problem.
    This is why people say leave it to cool in the PC / autoclave.. Lately I have put semi warm bags in cupboards in the hope that there is not a lot of contams floating in the air, and I do use sleeves anyway.

    Do some experiments that thoroughly protect against dirty air.

    It could be wrong bags but I doubt it, I think you are missing one of these steps that ensure that a vacuum is pulled upon cooling and instead you are sucking in dirty air.


    --------------------
    My trade lists:
  • Fungi - Edible / Gourmet
  • Fungi - Medicinal/Insecticides/Bioluminescents
  • Fungi - Actives
  • Fungi - Old Exotic Spores (Actives)
  • Fungi - Misc Hunted Mushroom Spores
  • Plants
  • Other items - Supplies etc.


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    Re: Cant get collapsed bags by end of pc cycle [Re: Solipsis]
        #25578483 -

    So, I have tried the PP bags and the results are the same, I dont get the brick like bags I would want to. I latter thought maybe I wasnt venting the autoclave long enough at the beggining of the cycle, which meant I was having too much air (instead of pure steam) inside the autoclave, which would prevent the formation of a "vacuum" at the end of the cycle. So I vented my autoclave for 20 minutes before the start of the cycle, and the result was exactly the same, which means, not what I wanted.

    I dont seal the bags before autoclaving, i just fold them. Sometimes I make the acordeon style folding. Anyway, it is possibe to see that there is some air inside the bags when I open the autoclave, before even touching them.

    My autoclave does pull a vacuum.

    I have no idea about the pore size of the filter bags, it might be a reason why I am getting contams, but I guess it would not explain why I dont get the brick like bags at the end of the cycle.

    I am trying to get the fully collapsed bags because this way I believe very little dirty air can get pulled inside of them when I open the autoclave. I am running out of ideas....

    Edited by vsoares (10/30/18 11:17 AM)

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    Re: Cant get collapsed bags by end of pc cycle [Re: vsoares]
        #25578630 -

    So your autoclave doesn't dump steam at the end of the cycle?  I have heard this is common and causes busted bags.


    --------------------
    Fiery Fungi (like us on faeboo)

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    Re: Cant get collapsed bags by end of pc cycle [Re: drake89]
        #25578701 -

    I can dump it manually if i open the valve. Maybe thats is the issue? I never tried doing that.

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    Re: Cant get collapsed bags by end of pc cycle [Re: vsoares]
        #25578997 -

    You want a slow cool the slow cool is what causes the vacuum. Same as with a PC.

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    Re: Cant get collapsed bags by end of pc cycle [Re: SHROOMSISAY01]
        #25579218 -

    You do tie them up right?

    Because just folding them may not work since if the bag expands during the cycle it could create an opening for air to pass perhaps big enough to prevent the bag from "choking on itself" like you want and what creates the vacuum.

    You can't look into your autoclave right? Would be helpful to see how the bags behave especially during cooling.


    With liquids like agar you definitely don't want to hasten the cooling because it can overboil, but is there really a problem when doing bags? I can't really think of a way faster pressure drop would prevent the bag from choking on itself and collapsing.


    Have you checked if used bags are still sealed and airtight?

    How full are you filling these bags and can you show a pic of a bag you prepared (and maybe others like of a bag after a cycle and your autoclave)

    What I don't know is if the filter patch allows for such low amounts of air passing that it couldn't play a role in preventing the vacuum collapse.
    In any case it doesn't make sense cause a lot of people have no problem doing this and you have tried it in so many ways, suggesting it is not such a cause as filter patches being blocked or not. But just for good measure: I think in almost all ways of folding the bag the patch should be getting blocked in a flat folded part.

    My suggestion for now is to try it with a weight placed on a bag to help it close and choke during cooling. Try to make sure there is little air left in the bag too.


    --------------------
    My trade lists:
  • Fungi - Edible / Gourmet
  • Fungi - Medicinal/Insecticides/Bioluminescents
  • Fungi - Actives
  • Fungi - Old Exotic Spores (Actives)
  • Fungi - Misc Hunted Mushroom Spores
  • Plants
  • Other items - Supplies etc.


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    Re: Cant get collapsed bags by end of pc cycle [Re: Solipsis]
        #25579231 -

    Trust me slow down the cooling and they will seal. But if you like I can start a tread on thermal dynamics.

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    Re: Cant get collapsed bags by end of pc cycle [Re: SHROOMSISAY01]
        #25579279 -

    My bags collapse fine in a small shitty PC that really doesn't take long to equalize the pressure when i turn off the heat. I definitely don't think that his autoclave is any quicker (without use of the manual valve of course).

    I'm interested in a little physics, can't you just explain a bit what you mean by what thermal dynamics mean for the difference in sealing/collapsing?

    Seems like from the moment the bag seals during cooling the further drop in pressure from the cooling relative to ambient conditions will cause contraction of the bag (probably consolidating the seal). So getting a good enough seal in the first place seems critical.
    I don't really see what happens if you do it very quickly, say near instantly.. hmm.. if there is a good enough seal to start with the same thing should happen.. or maybe if you do it slowly the seal is better because it adds up / consolidates / "crystallizes out" better.

    But still! Getting a good enough seal in the first place to seed this effect seems most critical. no>?

    If physics discussion helps to solve the problem, OP is probably fine with it


    --------------------
    My trade lists:
  • Fungi - Edible / Gourmet
  • Fungi - Medicinal/Insecticides/Bioluminescents
  • Fungi - Actives
  • Fungi - Old Exotic Spores (Actives)
  • Fungi - Misc Hunted Mushroom Spores
  • Plants
  • Other items - Supplies etc.


    • Edited by Solipsis (10/30/18 05:28 PM)

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    Re: Cant get collapsed bags by end of pc cycle [Re: Solipsis]
        #25579377 -

    Sorry I will be a little more careful with my jokes next time. I actually know nothing about thermal dynamics and I actually had to look up how to spell it. What I do know is from experience. I have never opened up my PC quickly but every time I open my 55-gallon steamer right after a cycle is done my top bags are loose but. If I wait for a day or two they are all sealed perfectly. The OP mentioned equalizing the pressure so I assume he is releasing the pressure which is his problem.

    What I believe is happening when you release quickly is the bag cools down much quicker than the spawn and evaporates any water on the plastic and never seals. When you let it cool down slowly it slowly pulls the bag together and does not evaporate the moisture between the two pieces of plastic the slow cool allows a tiny amount of water to remain, which, seals the bag then after it is sealed the further cooling of the spawn causes a vacuum and seals and evaporates the rest of the water on the bag.

    I believe the key here is flash evaporation. Open quick and it will flash evaporate the moisture on the bag or actually in between the two pieces of plastic of the bag where it should seal.

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    Re: Cant get collapsed bags by end of pc cycle [Re: SHROOMSISAY01]
        #25580677 -

    I'd guess if all your contams are coming in through the top there might be an issue with your seal. Are you using an impulse sealer? If so are you keeping it closed for an extra 5-10 seconds after you hear the click? If not Id put my money on that being your issue.

      Ive also had difficulties with inflating bags - especially sawdust bags - in the PC. I've solved this problem- and the problem of them occasionally melting - by wrapping them in a towel. I can only fit 2 6lbs bags at a time anyway so that extra space isnt wasted.


    --------------------





    Indoor Greenhouse Build 
              Mid Size Mushroom Farm

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    Re: Cant get collapsed bags by end of pc cycle [Re: TravelAgency]
        #25580680 -

    also are you using .2 mycron filter patches? .5 is too big for grain spawn but can be ok for sawdust.


    --------------------





    Indoor Greenhouse Build 
              Mid Size Mushroom Farm

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    Re: Cant get collapsed bags by end of pc cycle [Re: TravelAgency]
        #25580769 -

    TravelAgency said:
    also are you using .2 mycron filter patches? .5 is too big for grain spawn but can be ok for sawdust.


    I have no idea, I will check with manufacturer, you think if the pore size is too big the graion bags will contaminate anyway?

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