Secondary headspace and oxidation

[donshizzles]

I just racked my stout from the primary (2 weeks fermentation) to a 6.5 glass carboy to free up the primary bucket. I ended up with a fair amount of headspace in the secondary (about a gallon worth) and I am concerned that much might be a problem with oxidation, understanding this is a high gravity beer and needs to sit for a while before bottling.
I've read that even after it appears primary fermentation is complete, the mixing of the beer when being placed into the secondary can help with creating a small amount of CO2 to be made thus creating that CO2 cap on top. I don't want to dilute the beer by adding water to top it up so I just wonder if I will be ok leaving it to sit with that headspace for a few weeks

 

[m_stodd]

I just racked my stout from the primary (2 weeks fermentation) to a 6.5 glass carboy to free up the primary bucket. I ended up with a fair amount of headspace in the secondary (about a gallon worth) and I am concerned that much might be a problem with oxidation, understanding this is a high gravity beer and needs to sit for a while before bottling.
I've read that even after it appears primary fermentation is complete, the mixing of the beer when being placed into the secondary can help with creating a small amount of CO2 to be made thus creating that CO2 cap on top. I don't want to dilute the beer by adding water to top it up so I just wonder if I will be ok leaving it to sit with that headspace for a few weeks

Definitely don't add water to your beer. If you're worried about oxidation, (you shouldn't be in the case IMO), then adding water might oxidize it more.

Can you explain why you couldn't have just bottled instead of going to secondary? I'd recommend bottling as soon as it's as clear as you want it; it's not going to age any differently in a large container than in small containers, and it doesn't take long for yeast to clean up some byproducts after fermentation is done.

 

[grimzella]

It should be ok. The headspace will be replaced with gas from the fermentation.. at least when I secondary (at times) my airlock will bubble a small amount.. something must still be going on, that gas will push out any oxygen that was left, I would think ?

 

[AnOldUR]

The CO2 blanket is a myth. Gasses in the headspace will diffuse into a mixture of whatever CO2 escapes from the beer and ambient air. Personally, if I didn't have the proper size vessel to condition the beer, I would have bottled and let it condition there.

 

[donshizzles]

Not sure I agree with the CO2 blanket theory being a myth. There seems to be plenty of argument that CO2, if there is still a bit of fermentation taking place, will supply a CO2 barrier FOR AN AMOUNT OF SPECIFIED TIME.

Right now I am seeing a bit of bubbling in the airlock.....

 

[Yooper]

The CO2 blanket is a myth. Gasses in the headspace will diffuse into a mixture of whatever CO2 escapes from the beer and ambient air. Personally, if I didn't have the proper size vessel to condition the beer, I would have bottled and let it condition there.

Yes, I sort of cringe when I hear about this "co2 blanket" myself. I'm an old winemaker, and while I totally agree that active fermentation during primary will prevent any risks of oxidation and even do open primaries for my wines, that does dissipate as fermentation slows.

There may be some minute amounts of c02 in the headspace of a secondary, but if I remember my physics and the Ideal Gas Law, it's not that much.

That's why winemakers use campden tablets as an antioxidant and always reduce headspace to a minimal amount.

If you look at any infection threads, most of them are in fermenters that are either secondaries with lots of headspace, or beers that have been in a lengthy primary with a wide headspace.

Anyway, short term a lot of headspace is probably just fine, but for a long time I'd either use the appropriate sized carboy, or just bottle the beer.

 

[donshizzles]

Yes, I sort of cringe when I hear about this "co2 blanket" myself. I'm an old winemaker, and while I totally agree that active fermentation during primary will prevent any risks of oxidation and even do open primaries for my wines, that does dissipate as fermentation slows.

There may be some minute amounts of c02 in the headspace of a secondary, but if I remember my physics and the Ideal Gas Law, it's not that much.

That's why winemakers use campden tablets as an antioxidant and always reduce headspace to a minimal amount.

If you look at any infection threads, most of them are in fermenters that are either secondaries with lots of headspace, or beers that have been in a lengthy primary with a wide headspace.

Anyway, short term a lot of headspace is probably just fine, but for a long time I'd either use the appropriate sized carboy, or just bottle the beer.

Its already in the carboy, so how long am I good leaving it in there before bottling? 1 week? 2 weeks?

 

[Yooper]

Its already in the carboy, so how long am I good leaving it in there before bottling? 1 week? 2 weeks?

If it's done, and you're not adding fermentables or something, it should be bottled when you have a chance.

I don't know how long that is- it is probably fine for the short term, but I don't know how many mold spores or other things are in the air in your house or how much c02 is still in suspension in the beer (to protect the beer from oxidation).

 

[issekremaaa]

I was in the same boat as you, made a beer that i oaked in secondary but carboy was a bit too big for it. I have one of these,

http://www.briscoes.co.nz/kitchen/appliances/sodastream/1035755/Sodastream-Pure-Machine.html

at home so just got a bit of vinyl tubing and filled the remaining headspace with co2 before quickly putting the airlock back on. I didnt taste any oxidation related off-flavors even after lagering it for many months.

 

[Riot]

Is there any reason you couldn't add about an ounce of sugar to the secondary to produce enough co2 to force out the ambient air? It sounds like it should work fine at face value, but I really don't have enough experience to know definitively.

 

[LakesideBrewing]

OK, I'm confused now. Are some of you saying that fogging a carboy with co2 is useless? When I have excessive headspace in my carboy I usually just 'lay a blanket of co2' (sorry to make you cringe ) on top of my aging beer. Am I wasting my time? Or just getting lucky with no oxidized beers?

-Mike

 

[AnOldUR]

There are legitimate reasons to move even a stout to a secondary vessel, but regardless of your purpose, one of the things it will accomplish is that the time there will give the beer a chance to clear. Adding sugar to reactivate the yeast would be counterproductive. If the yeast are done and it's clear enough for you, package it.

The thing I find strange here is that you moved it to a 6½ gallon carboy to free up a bucket. Why didn’t you simply brew your next batch in the carboy and let the stout clear in its primary?

... I usually just 'lay a blanket of co2' (sorry to make you cringe ) on top of my aging beer. Am I wasting my time?

Purging is good and effective. It's the term "blanket" that we have a problem with. It's very unlikely that you'll accomplish a complete purge of all the ambient air from your head space. Hopefully you'll end up with a relatively rich CO2 content. But the gasses will diffuse into a mixture of what is present. The concept that CO2 is heavier and will blanket your beer is the myth repeated often on HBT.

 

[Wynne-R]

Can we call it a “fog”? It doesn’t have sharp boundaries and you know it won’t last forever. You can imagine it displacing air even as it mixes with air.

 

[Yooper]

Can we call it a “fog”? It doesn’t have sharp boundaries and you know it won’t last forever. You can imagine it displacing air even as it mixes with air.

That's a great way to think of it! Even in a keg that has been purged, it's never going to be 100% Co2, but closer than without purging.

I was recently doing some reading on Better Bottles and oxygen permeability of HDPE fermenters, and what was pointed out was than for winemakers, even topping up doesn't guarantee NO oxygen exposure. For example, the water in the airlock. It can be a source for a small amount of 02 permeability as gasses work to find equilibrium. Still you want to minimize the oxygen exposure as much as possible, and reducing headspace after fermentation slows is a cheap and easy way to accomplish that.

Edit- added the link of the study: http://www.better-bottle.com/pdf/CarboyPermeabilityStudy.pdf Scroll down to get past the better bottle stuff, under "methodology" to see what they say about purging/flushing the carboy with c02 and its effectiveness.

This link contains the info on closures/bungs/water in the airlock: http://www.mocon.com/pdf/optech/Closures - Oxygen Passage Study.pdf

 

[worthogg]

Some good info here...

 

[helibrewer]

That's a great read Yooper. From the winemaking perspective it would be interesting to compare barrel aging to Better Bottle aging with respect to micro-oxygenation.

I haven't come across much info about MOX in beer aging. The take-aways for me with regard to beer are:

1) Only secondary when absolutely necessary.
2) Do not open the primary for testing until the beer has visibly cleared and aged appropriately and you are prepared to go straight to keg or bottle after testing. The best vessel purge is primary fermentation
3) If you are really concerned, close-pressure ferment.

 

[AnOldUR]

Can we call it a “fog”?

No you may not.

Fog is actually a liquid and does not have the diffusion properties of gasses.

 

[NewWestBrewer]

No you may not.

Fog is actually a liquid and does not have the diffusion properties of gasses.

"Check out the big brain on Brett" :rockin:

 

[HerrHepcat]

"Check out the big brain on Brett" :rockin:

Now I want a Royale with Cheese.

With a homebrew.

 

[Yooper]

No you may not.

Fog is actually a liquid and does not have the diffusion properties of gasses.

Ouch. Now my brain hurts.

C02 is a liquid, dispensed as a gas. So there!

 

[AnOldUR]

C02 is a liquid, dispensed as a gas. So there!

There's a joke there about having gas that's dispensed as a liquid,
but I won't go there.




Oh wait, I think I did.

 

[Wynne-R]

C’mon AnOldUR; Yooper liked it.

‘Fog’ is a much better metaphor than ‘blanket’. Did you think people were talking about actual blankets?

 

[Yooper]

C’mon AnOldUR; Yooper liked it.

‘Fog’ is a much better metaphor than ‘blanket’. Did you think people were talking about actual blankets?

As much as this is making me smile (and think a bit!), I don't like either description actually.

A "blanket" denotes something almost impenetrable, so I hate that term and I cringe when I hear it parrotted on the forum.

"Fog" is better, in that it's something that appears but then dissipates as the day warms.

We need a new and improved way to describe this! Referring non-scientific minded people to the Ideal Gas Law isn't the way- but describing this imaginary c02 blanket as a fail-safe is also wrong. I'd be open to a clear, concise way to refer to the c02 and its protective effect during fermentation, and the way it dissipates!

 

[AnOldUR]

Referring non-scientific minded people to the Ideal Gas Law isn't the way-

So, if I tell you it's actually this:

Not this:

it won't help?







. . . not a fan of sour beers, why would my brain be on brett?

 

[peterj]

So, if I tell you it's actually this:

Not this:

it won't help?

Nice, I noticed that as well and was trying to think of a way to phrase it. Well done!

 

[worthogg]

Can we call it a “fog”? It doesn’t have sharp boundaries and you know it won’t last forever. You can imagine it displacing air even as it mixes with air.

No you may not.

Fog is actually a liquid and does not have the diffusion properties of gasses.

So is it more like a fart in a car?

 

[nubrewer82]

So is it more like a fart in a car?

I think that's more akin to smoke than to fog...... but maybe it depends on what you've been eating?

Maybe it will help some folks to think of O2 and CO2, etc being different colors.

Instead of creating colored layers, they blend together to make a new color.

 

[dannysk]

Agree that O2 in this slow secondary fermentation could be a problem. Two suggestions in order to help eliminate the O2:

1. Slowly purge the aging vessel with CO2 - use a wand and add the CO2 VERY slowly to avoid mixing with O2. Pure CO2 at the bottom is the goal.
2. Rack the beer using the same technique whereby beer is added very slowly, without splashing from the bottom.

If done correctly, the CO2 at the bottom of the vessel will be a barrier between the beer and the air/O2 above it. If enough CO2 was added, it will stay at the bottom (on top of the beer) as you fill.

Good luck.

 

[donshizzles]

So after racking to secondary and having all this headspace I was paranoid about, I decided the next day to just bottle and hope for the best.

Today was exactly 2 weeks to the day that I bottled so I decided to sample one to make sure carbonation was ok and to see how its progressed.

The carbonation was PERFECT and the taste was amazing. I was fully expecting a measure of "green" to the taste but quite frankly it was outstanding. I figure in another month this beer is going to be awesome. :rockin:

 

[dannysk]

A "blanket" denotes something almost impenetrable, so I hate that term and I cringe when I hear it parrotted on the forum.!

I'm still a fan of the "old school" traditional term, blanket; maybe because I have used it so long. Also, my blankets are clearly not nearly as good as yours so it makes more sense to me.

If CO2 blanketing correctly, it's only meant to be a barrier between the beer and the O2 above the beer while filling. Then, the O2 gets pushed out when the tank is full... in this context, it really does look like a blanket.

Air
CO2 Blanket
Beer

 

[Bluedog]

So after racking to secondary and having all this headspace I was paranoid about, I decided the next day to just bottle and hope for the best.

Today was exactly 2 weeks to the day that I bottled so I decided to sample one to make sure carbonation was ok and to see how its progressed.

The carbonation was PERFECT and the taste was amazing. I was fully expecting a measure of "green" to the taste but quite frankly it was outstanding. I figure in another month this beer is going to be awesome. :rockin:

What you've done is no different than someone opening the lid of a primary bucket to check gravity when fermentation slows. people do that everyday and then repeat it 2 or 3 times over the course of days to weeks to make sure they've hit terminal gravity. Why would this situation be any different?

 

[donshizzles]

What you've done is no different than someone opening the lid of a primary bucket to check gravity when fermentation slows. people do that everyday and then repeat it 2 or 3 times over the course of days to weeks to make sure they've hit terminal gravity. Why would this situation be any different?

Okay.......not sure what your point is but was just throwing it out there that despite me being paranoid about oxidation from too much headspace in the secondary, I just bottled it right away and it worked out.

 

[Bluedog]

Okay.......not sure what your point is but was just throwing it out there that despite me being paranoid about oxidation from too much headspace in the secondary, I just bottled it right away and it worked out.

No offense meant there pardner.

 

[raouliii]

.....
If CO2 blanketing correctly, it's only meant to be a barrier between the beer and the O2 above the beer while filling. Then, the O2 gets pushed out when the tank is full... in this context, it really does look like a blanket....

I believe the point of a few of the previous posts is that it doesn't work this way. No matter how slowly you inject co2, it will readily mix with the existing air. There is no layering or separation. It becomes an issue of increasing the co2/air ratio which reduces the o2 to an acceptable level. Keg "purging" works the same way.

I believe co2 in a primary is a little different issue. During the yeast lag phase most of the o2 in the headspace is consumed by the yeast and the co2 produced by the yeast dilutes any o2 left. Thereby protecting against oxidation. Opening the primary allows air back in that readily mixes with the headspace co2.