Bulk Aging: Concern for oxidation in the fermenter headspace

[Butch Douthit]

I have a half barrel SS Brewtech Chronical fermenter. When going through the 2-4 months of secondary fermenting/clarification, or, if I decided to leave the batch in the fermenter for longer term aging (say a year)... How concerned should I be regarding the potential contamination or oxidation of the batch?

Has anyone ever used a floating membrane inside the fermenter to limit surface exposure to air inside. the fermenter.

I watched a youtube video that suggested using a heavier than air, inert gas like Argon to displace the oxygen. This would be pretty spendy... I found the cost of getting set up with a basic tank/regulator/gauges/etc of Argon would be about $500. After the initial setup refills would only be $70-90 ...but still that is a pretty significant investment

 

[VikeMan]

I have a half barrel SS Brewtech Chronical fermenter. When going through the 2-4 months of secondary fermenting/clarification, or, if I decided to leave the batch in the fermenter for longer term aging (say a year)... How concerned should I be regarding the potential contamination or oxidation of the batch?

Has anyone ever used a floating membrane inside the fermenter to limit surface exposure to air inside. the fermenter.

The key is to keep O2 out of the fermenter in the first place. If you open the fermenter to put a "membrane" in, you'll be allowing O2 into the headspace, which will find its way around and/or through any membrane, unless it's made of something like stainless steel and somehow fit to the fermenter walls in an airtight way.

I watched a youtube video that suggested using a heavier than air, inert gas like Argon to displace the oxygen. This would be pretty spendy... I found the cost of getting set up with a basic tank/regulator/gauges/etc of Argon would be about $500. After the initial setup refills would only be $70-90 ...but still that is a pretty significant investment

Argon (or any gas) will freely mix with any oxygen present, and vice versa.

 

[Butch Douthit]

The key is to keep O2 out of the fermenter in the first place. If you open the fermenter to put a "membrane" in, you'll be allowing O2 into the headspace, which will find its way around and/or through any membrane, unless it's made of something like stainless steel and somehow fit to the fermenter walls in an airtight way.



Argon (or any gas) will freely mix with any oxygen present, and vice versa.

First of all... thanks for the reply.

My concern is that In order to do certain things like a battonage where you need to stir the batch every 2-3 weeks for as much as a year, I will introduce air to fermenter each time... In a case like that, it is not possible to avoid intro of oxygen.

As for the membrane, I am thinking about cutting the top out of a food grade PVC barrel... (I still need to check a small chunk first to see if it floats ...if not, I'll be left searching for something else relatively impermeable that floats... or perhaps getting my brother, a cabinet maker to build me a round oak disk with a handle... maybe I could get two things out of it... ie a little oak tannin !!! ...heheheh)

Argon is 40 % heavier than air, so it should settle as a cap over the wine as long as it is applied gently. Part of the question would be... Am I more at risk of introducing anaerobic activity if air is not allowed to get to the top surface of the wine, or is oxidation a bigger threat.

 

[AMessenger]

My concern is that In order to do certain things like a battonage where you need to stir the batch every 2-3 weeks for as much as a year, I will introduce air to fermenter each time... In a case like that, it is not possible to avoid intro of oxygen.

Very interesting. What are you up to? Would seem like introduction of oxygen would largely be the point of introducing a process like that.

A beer stored in secondary for a year is going to be different than one packaged after a couple months most likely but that isn’t a bad thing necessarily. Floating cap and argon sound like way more trouble than they’re worth to me - I think you’d be more likely to harm the product than help fiddling around with either of those

 

[VikeMan]

Argon is 40 % heavier than air, so it should settle as a cap over the wine as long as it is applied gently.

Usually, it's the mythical "CO2 blanket" that gets traction around here. But argon is no different in that respect. The argon will barely matter, except for any random collisions that happen to bounce O2 molecules temporarily away from the beer, which delays the inevitable, but only for a little while.

The gasses will mix completely. This video demonstrates what I'm talking about. Note that they used Br2, which is whole lot heavier than the argon you're contemplating. Doesn't matter.

 

[Butch Douthit]

Usually, it's the mythical "CO2 blanket" that gets traction around here. But argon is no different in that respect. The argon will barely matter, except for any random collisions that happen to bounce O2 molecules temporarily away from the beer, which delays the inevitable, but only for a little while.

The gasses will mix completely. This video demonstrates what I'm talking about. Note that they used Br2, which is whole lot heavier than the argon you're contemplating. Doesn't matter.

this was great... thx

My understanding is that the inert gas is to replace the air in the head space to the extent possible. It is good though to know that whatever air remains in the top of the fermentor will mix completely with the inert gas. The picture I had in my head was one of layers until watching the video

 

[Butch Douthit]

Very interesting. What are you up to? Would seem like introduction of oxygen would largely be the point of introducing a process like that.

A beer stored in secondary for a year is going to be different than one packaged after a couple months most likely but that isn’t a bad thing necessarily. Floating cap and argon sound like way more trouble than they’re worth to me - I think you’d be more likely to harm the product than help fiddling around with either of those

...not beer, a wine... perhaps you meant wine

...the battonage process is not to introduce oxygen, but to extract flavors from the yeast lees.

 

[Yooper]

I rarely use battonage, and definitely not for a long term, but if you sulfite appropriately and are cautious about stirring vigorously, and top off with c02, you can reduce the risk of oxidation.

 

[Butch Douthit]

Based on feedback so far, perhaps I've over estimated the concern for oxidation. If I add the correct amount of potassium metabisulfite, limit taking the lid off the fermenter to the bare minimum, and stir gently when I do take the lid off, I should be ok. Great... I feel like I just saved $500 for an inert gas setup

I think I will build a 15" round oak, floating cap block to set inside the fermenter after primary fermentation is done. The 15 inch diameter oak insert would leave about 1/4 inch between the floating oak insert and the sidewall of the fermenter to limit oxidation during an extended secondary clearing/aging period before I bottle. I will be able to remove the oak insert if needed to make twinks to the wine or to stir lees if desired.