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Controlling Bacteria

So is have a situation where because I use smaller fermenters and the boiler size is smaller than one fermenter that it gets tricky to plan distillations based on completed ferments and juggle production and ferment starts. I’m working on a more consistent schedule for ferments now.

As a result some of my ferments might sit for as long as a week after completion. At times they will start to give off a acetic smell when they are closer to dry. I’d like to stop bacteria activity after dryness and kinda put the ferment in stasis till I can get to it.

My two immediate thoughts are to acidify the wash to prevent bacterial growth (2.5?). And to put a UV lamp in the barrel to kill everything off.

What can I do to stop off flavors developing if the ferment sits for a few days.


  • Open or closed fermenters? Acetic acid bacterias are generally aerobic, a closed fermenter will prevent it. If you have open maybe do something to try and close it off? I don't think that would be simple.

    Campden tablets would work too but would add sulfer. Probably not a good idea either.

    I appear to not be much help... Sorry.

  • edited January 2020

    As @SingleMaltYinzer says, acetobacters metabolize oxygen and alcohol into acetic acid (vinegar). If you can keep a carbon dioxide, or pure nitrogen gas blanket over the surface of your ferment, acetobacters will not be able to get a foothold in the absence of oxygen.

    I use carbon dioxide from my beer kegging system to purge the air out of the headspace over my long-term stored ferments. A friend of mine does the same thing using argon from his welder.

    Stay away from sulfite additions. They carry-over into the distilled spirit bigly.

    I'm more like I am now than I was before.

  • Best solution is CO2 because of its density. Nitrogen is the lightest.

  • The fermenters are open but covered. Not airtight or airlocked.

  • Hydrogen is the lightest.

    I'm more like I am now than I was before.

  • ;)) And taking the fermentor away with it.

  • How big are your fermenters? Could you rack the wash off to a tote or something else you could put CO2 in the headspace?

  • Can't you fortify with a bit of ethanol to raise the alcohol %?

    StillDragon North America - Your StillDragon® Distributor for North America

  • What Larry said. tip some strip in there.

    StillDragon Australia & New Zealand - Your StillDragon® Distributor for Australia & New Zealand

  • I use 170 gallon SS ferment tanks with light weight, not airtight lids.

    I let Ph crash near end of ferment on purpose and when finished add previous tails as much as and as available. They're going in the boiler anyway and you get them back.

    I tried acidifying with Citric acid. Don't use Citric acid! It is a calling card for fruit flies.

    DAD... not yours.. ah, hell... I don't know...

  • edited January 2020

    I did add some citric yesterday to lower ph.

    How much ABV do I need to prevent bacteria? I should be between 9 and 13 now.

    Fermenters are 200l

    Adding gasses not created by me is kind of a non starter. A cylinder of co2 is $200usd to rent. Welding gasses are crazy here. Argon is like $500 for a cylinder.

  • There's a Pearsons Square calculator here you can use. Get it up over 25% and won't be much growing in it that's for sure.

    StillDragon Australia & New Zealand - Your StillDragon® Distributor for Australia & New Zealand

  • That’s probably not doable. In don’t have anywhere near the tails to do that high.

    I could bump it a few percent tho. Maybe put 5l tails in each.

  • I've never had problems with washes getting infected and i've left th3em covered but unsealed for months. Mostly rum and ujsm etc. had plenty of infections in beer but i think the 10-15% abv makes it pretty inhospitable. What makes you think you are getting infections besides the sour wine smell? Have you tasted them?

    StillDragon Australia & New Zealand - Your StillDragon® Distributor for Australia & New Zealand

  • Mostly the vinegar smell. It seems to take hold when it approaches dry with the sugar wash I’m doing.

    Maybe it’s a ph thing or maybe it’s nutrient depletion.

    I had a batch of neutral come over with a really sharp mid pallate burn that was not normal. Couldn’t distill it out or filter it out. It wasn’t working with our product so I’m kinda paranoid that maybe acetic acid production could have been a factor. Looking at the data I think it was more likely temperature related but I won’t know until this batch distills Monday. If it’s bacteria causing the sharp heat then I might be in trouble. If it’s temperature then I’m good.

    A possible third factor is adding more sugar and nitrogen in the last third of fermentation. I actually did that to encourage and lengthen the yeast production cycle to stave off the acetic smell tho.

    Which of those three factors might produce that sharp heat bite in sugar wash? (Assuming I have it in hand otherwise)

  • Mate you are going to get the right basis to judge by tasting, at least that would be my approach. Get a sample jar and taste the wash.

    StillDragon Australia & New Zealand - Your StillDragon® Distributor for Australia & New Zealand

  • edited January 2020

    As far as the cost of carbon dioxide goes, if you have dry ice available, you can drop a piece of dry ice into your fermentation vessel and as it evaporates it will create a CO2 blanket over the liquid. Being heavier than air, the CO2 will displace the ambient air and be contained in the vessel like a bowl. The small amount needed will be inexpensive and will not freeze anything as it evaporates.

    I'm more like I am now than I was before.

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