Fermentation with silicone tubing?

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PeeBee
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Fermentation with silicone tubing?

Post by PeeBee » Thu Nov 02, 2017 4:29 pm

Silicone tubing. Expensive, but withstands boiling liquids, easily kept sanitary, doesn't leach out nasty chemicals. The be all and end all for tubing to use in home-brewing. But is it ...

I had a bit of an "infection" scare in the last few weeks. Two consecutive brews (45L each!) both taking on an acetic (vinegar) twang. I suppose it was natural justice as I do have a bad opinion of the "modern" trend of blaming anything not right with a brew on "infection".

These were the same two brews I was discussing in recent threads because I was having a few issues with excessive yeast growth using WLP002. First time using that yeast, also only the second time using pure oxygen for aerating the wort and the first time employing the new temperature control on the fermenter. So plenty of variables to work on. The yeast or pure oxygen couldn't be causing the acetic twang or there would be lots said about it. So the new temperature control was the culprit. It involved occasionally recirculating (pump) the fermenting beer through the product coils of a shelf cooler (new Maxi310 clone, not second hand). The previous brew was the first time I'd used liquid yeast and pure oxygen, but I hadn't got the cooling system in place - it is fine.

So the product coils were harbouring some nasty bug? This was the conclusion I reached despite having flushed the coils with VWP. But what could a couple of plain stainless steel coils harbour? Cracks in the pipe wall so a poor seal against the very unsanitary cooler's water bath? Wherever the bugs come from, they need a source of oxygen to convert alcohol to vinegar (at least that's my understanding), so where's that coming from? So having redesigned my cooling system I start having second thoughts.

The cooling system has another component - platinum cured silicone tubing. It transferred beer between the fermenter and cooler, so more times than not beer remained stationary in these pipes. I thought I'll look up the permeability to oxygen. Shock. It is very permeable, so much so the feature is used in medical equipment. Silicone tubing is NOT suitable to have beer hanging about in it for too long? Or have I got this wrong as I don't see anyone complaining about it? Could silicone tubing be the source of my woes?


FOOTNOTE: The 90L of ruined beer? Well it got casked, and in one beer there is no hint of acetic (no hint of acetic in the other beer, but the flavour might not be what I expected). Still, I'm terrified the beers will suddenly become vinegar so I'm drinking them quick - the beer's not ruined (yet) but I'm heading to ruination!

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Re: Fermentation with silicone tubing?

Post by Dads_Ale » Thu Nov 02, 2017 8:43 pm

Hi PeeBee

Not sure this is the cause of your woes but these are my observations of silicone tubing:
  • Most of mine that I use for transfer have discoloured
    I used some as a dip tube for a keg of cider and it took up the cider twang and I had to replace it
      My FV cooling uses silicone tubing and I can smell hops in the cooling water
    The above leads me to believe that silicone tubing left in contact with beer for an extended period may cause issues.

    On another note, following a thread on stripping down ball valves, I found it quite surprising how dirty things got even when you think you have flushed them through adequately.

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    Re: Fermentation with silicone tubing?

    Post by Kev888 » Thu Nov 02, 2017 10:41 pm

    Many of us use silicone hose, with no ill consequences at all. It isn't particularly impermeable but I doubt that it could allow (relatively) big stuff like infections through during the course of a fermentation. If you think it is contributing to infection then it could be worth considering if your initial cleaning and disinfecting of it (i.e. before each use) is sufficient.

    But.. if I understand correctly, you have a relatively complex and unconventional system. It is more normal to move unimportant coolant to the wort/beer or fermenter via coils or jackets (typically seamless where they exchange with the beer). For good reason too; moving wort to the coolant, with presumably pumps and joins etc in the wort's path as well as the tubing, is inherently a harder task to disinfect and protect from excessive oxygen ingress.

    Not impossible, and not at all unheard of - some types of yeast can be roused in a similar way for instance. But given the significant extra risks involved then extra-high levels of care are needed. TBH words like 'rod' and 'back' come to mind and I'm not sure that VWP would cut the mustard for me in this situation. If the components can take it then a caustic clean followed by steam or a peracetic acid (or possibly strong bleach) disinfection stage would be my preference.

    I'd be particularly suspicious of weak spots like ill-designed pump heads and hose/tail joins. Even the cooler coil is somewhat out of its comfort zone; beer on the way to the glass has little time to propagate any infection, but things are different with sugary wort weeks or months away from being consumed.

    Though don't dismiss the possibility of unrelated causes. Many factors can cause strange flavours in beer, especially green beer, and at least some of yours seems to have recovered... which does not irrefutably suggest infection or oxidation to me. More likely unfavourable fermentation or possibly mash conditions which the yeast etc. are making good over time.
    Kev

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    Re: Fermentation with silicone tubing?

    Post by PeeBee » Fri Nov 03, 2017 1:13 am

    I have been cooling using external coils, using the cooler's product coils seemed like a good idea at the time and is much faster. I haven't decided yet whether to continue using the product coils to get rapidly to fermentation temperature then disconnect so I'm only recirculating for an hour or so (the counter-flow cooler is none too good at getting wort temperature below 20C).

    But I wasn't looking at silicone hose as the source of acetic acid bacteria, but as the source of oxygen that the bacteria will need to create acetic acid. I was never really comfortable about pumping fermenting beer anywhere, so it's probably just as well I've been pushed to giving up the use of the cooler's product coils. I like the idea that I could be confusing an acetic twang with some other transitory flavour in the green beer as it would explain why the beers have miraculously recovered, but an acetic twang is pretty hard to confuse, and I won't be sure there has been a recovery until the beer is all drunk.

    The post is more about possibly dispelling misguided use of silicone hoses. Assuming I'm not the only person being misguided.

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    Re: Fermentation with silicone tubing?

    Post by orlando » Fri Nov 03, 2017 8:42 am

    Until you know whether or not you have a "problem/infection" is there anything to discuss yet, you seem rather unsure?
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    Re: Fermentation with silicone tubing?

    Post by PeeBee » Fri Nov 03, 2017 10:17 am

    orlando wrote:
    Fri Nov 03, 2017 8:42 am
    Until you know whether or not you have a "problem/infection" is there anything to discuss yet, you seem rather unsure?
    Ahh. That makes the mistake of thinking I'm talking about an infection. I'm pretty sure of that, a mouthful of vinegar is quite hard to be unsure about, but as acetic acid bacteria are aerobic I'm happy with it being there in a "latent" state. I can't be 100% sure of an acetic acid bacterial infection because I don't have the lab facilities to hand.

    What I want to discuss is the potential for oxygen mixing with the beer because I have silicone tubing connected to the fermenter. Not a normal situation but perhaps one others have had it or are planning to have it. I have determined the tubing is permeable to oxygen (very much so). Maybe there is a more suitable alternative? Feedback so far is convincing me to rethink the cooling configuration of the fermenter.

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    Re: Fermentation with silicone tubing?

    Post by PeeBee » Fri Nov 03, 2017 12:37 pm

    Dads_Ale wrote:
    Thu Nov 02, 2017 8:43 pm
    Hi PeeBee

    Not sure this is the cause of your woes but these are my observations of silicone tubing:
    • Most of mine that I use for transfer have discoloured
      I used some as a dip tube for a keg of cider and it took up the cider twang and I had to replace it
        My FV cooling uses silicone tubing and I can smell hops in the cooling water
      The above leads me to believe that silicone tubing left in contact with beer for an extended period may cause issues.

      On another note, following a thread on stripping down ball valves, I found it quite surprising how dirty things got even when you think you have flushed them through adequately.
      Thanks Dads_Ale. I do use silicone for my keg dip tubes (Caskwidge floating extractors), but only use beer in them. I'm not too concerned with them because the silicon tubing is not providing a barrier to anything. Interesting that you've experienced take up of taints and colour by silicone tubing, 'tain't as "neutral" as many of us might hope (having paid so much for it).

      The floating extractors displayed another "benefit": Purging the headspace of newly filled kegs with CO2 can't get rid of all the air - the first glass or two from the affected kegs had an acetic taint but this went away with subsequent glasses (the bugs had used all the available O2?). If extracting beer from the base of the keg I wouldn't notice this until the keg is almost empty, or shook up.

      I can't face dismantling ball-valves, but "pasteurise" them by recirculating the boiler contents through them for 3-5 minutes prior to run-off (the temperature sensors suggest I get them, the CFC and any pipework, up to 85-90C doing this).

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      Re: Fermentation with silicone tubing?

      Post by orlando » Fri Nov 03, 2017 1:29 pm

      PeeBee wrote:
      Fri Nov 03, 2017 10:17 am
      orlando wrote:
      Fri Nov 03, 2017 8:42 am
      Until you know whether or not you have a "problem/infection" is there anything to discuss yet, you seem rather unsure?
      Ahh. That makes the mistake of thinking I'm talking about an infection.
      It's a good idea to think about how the bacteria is getting in before worrying about O2. Is there a diacetyl hint in the beer, this would point to pediococcus? Can't remember now if the beer finished a lot lower than expected, if so lactobacillus could be the problem, see I avoided the word infection. :D
      I am "The Little Red Brooster"

      Fermenting: Kernel Bogey (Reprise)
      Conditioning: St. Petersburg (RIS) White On Blonde
      Drinking: Mild In The Country, Summer Son, Duke Of Jarl
      Up Next: Peaches (Peach IPA)
      Planning: Summer drinking beer.

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      Re: Fermentation with silicone tubing?

      Post by PeeBee » Fri Nov 03, 2017 4:10 pm

      orlando wrote:
      Fri Nov 03, 2017 1:29 pm
      ...
      It's a good idea to think about how the bacteria is getting in before worrying about O2. Is there a diacetyl hint in the beer, this would point to pediococcus? Can't remember now if the beer finished a lot lower than expected, if so lactobacillus could be the problem, see I avoided the word infection. :D
      Thanks Orlando. No off-flavours other than acetic acid. Drinking the beer at the moment doesn't suggest there was anything wrong. The beer did finish lower than expected (FG 1.006, 84% attenuation) but other discussions suggest this isn't unusual for this yeast (WLP002) despite being well out of the specs (I did mash at 64C). So, I suspected acetic acid bacteria, and as they "hibernate" in anaerobic conditions I started looking for the source of oxygen. And found one!

      Also knew beer held stationary in these tubes (linking fermenter and chiller) was particularly acetic; which fits well with knowing oxygen will get into the tubes. But previously I had suspected the chiller to be the source of bugs - can't be so sure now.

      Occurred to me in the past hour, beer in my hand-pumps would become acetic after a day or two. Thought nowt of it as the hand-pumps were open to the air (they aren't any longer - one of my "improvements"). Perhaps acetic acid bacteria is just endemic in the house? But it is thwarted easily by keeping O2 out of contact. Hence I WILL worry about O2.

      Came across this earlier, sort of supports my babblings: "Due to the <silicone> tubing's higher-than-vinyl oxygen permeability, we don't recommend this for permanent installations where it will have product sitting in the lines." https://morebeerpro.com/products/316-id ... -foot.html.

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      Re: Fermentation with silicone tubing?

      Post by Kev888 » Fri Nov 03, 2017 4:29 pm

      Am I right in thinking this is the beer that was fermented rather warm for the yeast type, and that more or less reached FG in the blink of an eye?

      If so then it is really quite possible you're just tasting fermentation by-products. Though whilst the amount of attenuation isn't unheard of for wlp002 the FG 'is' rather low for it, so it is hard to be confident there isn't also some kind of infection.

      I'd be interested to hear if these suspected problems simply vanish if/when the next brew is carried out with a more normal fermentation rate.
      Kev

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      Re: Fermentation with silicone tubing?

      Post by PeeBee » Fri Nov 03, 2017 5:26 pm

      Kev888 wrote:
      Fri Nov 03, 2017 4:29 pm
      Am I right in thinking this is the beer that was fermented rather warm for the yeast type, and that more or less reached FG in the blink of an eye?

      If so then it is really quite possible you're just tasting fermentation by-products. Though whilst the amount of attenuation isn't unheard of for wlp002 the FG 'is' rather low for it, so it is hard to be confident there isn't also some kind of infection.

      I'd be interested to hear if these suspected problems simply vanish if/when the next brew is carried out with a more normal fermentation rate.
      Hi Kev. Yeap, that's the one. But also the following brew where temperature was better controlled, pitch rate reduced, didn't overdo oxygenation and fermentation was relatively sedate (3 days). The "blink-of-an-eye" brew had an FG of 1.013 and attenuation of 76%.

      But if it was fermentation by-products I can imagine finding much more to read concerning using this yeast. It really was acetic, in both cases.

      And I'm talking as if the problem is sorted. Even if my assumptions are right, the problem has only been pushed to the background for now and might establish itself again soon (excuse to keep drinking too much of it while it's good).

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      SOLUTION?

      Post by PeeBee » Fri Nov 03, 2017 5:33 pm

      I'll repeat this rather conclusive statement for anyone speed reading through some large posts (least they miss it - I think it's important?):
      PeeBee wrote:
      Fri Nov 03, 2017 4:10 pm
      ... Came across this earlier, sort of supports my babblings: "Due to the <silicone> tubing's higher-than-vinyl oxygen permeability, we don't recommend this for permanent installations where it will have product sitting in the lines." https://morebeerpro.com/products/316-id ... -foot.html.

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      Re: Fermentation with silicone tubing?

      Post by orlando » Fri Nov 03, 2017 6:06 pm

      I didn't say "don't worry" about O2. Dealing with the bacteria was my point. Clearly a bacteria source that is aerobic will thrive in an O2 rich environment so sure don't give it one. My point I suppose is concentrate on the steps before fermentation and I am not going to lecture you on sanitation, that's a given. I would be interested in your entire process pH measurements right up to drinking the beer after it has been packaged for a few weeks. You should see little to no difference between completely fermented out beer and that measured a month or two later. If there is a difference we have an objective "measure" of a problem at least, not just sensory evaluation, even if we still can't identify the beast.
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      Drinking: Mild In The Country, Summer Son, Duke Of Jarl
      Up Next: Peaches (Peach IPA)
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      Re: Fermentation with silicone tubing?

      Post by f00b4r » Fri Nov 03, 2017 6:22 pm

      Also bear in mind that silicone tubing is soft so you might actually be letting oxygen in at the end of the tubing where it is connected, ie it is slightly deformed, rather than through the walls itself.

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      Re: Fermentation with silicone tubing?

      Post by PeeBee » Fri Nov 03, 2017 6:27 pm

      orlando wrote:
      Fri Nov 03, 2017 6:06 pm
      I didn't say "don't worry" about O2. ...
      Sorry, I appear to have misquoted you. Wont be able to supply many historic pH records, but does make sense to start now should the problem come back (I'm relieved I haven't lost 90L of beer, but my explanations are assumptions and I might yet still suffer a relapse). Thanks.

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