"A blanket of CO2"

[ArcaneXor]

that is like saying water is heavier then alcohol so there is more alcohol in the top of your beer then the bottom. (since both will obey the laws of fluid dynamics)

Tell that to the people who died in the Lake Nyos disaster.

Of course O2 and CO2 will mix, which is why the the amount of CO2 measured pretty much anywhere on the planet is fairly close to the planetary average. But over short time periods, especially when the air isn't moving much, massive releases of CO2 will hug the ground, diluting the O2 concentration and either killing people and livestock, as with Lake Nyos, or sitting on top of the beer. If you don't agitate the head space, the concentration of O2 that enters it within the couple of minutes we may have it un-stoppered is very small. The other thing is that diffusion of O2 into water (or wort) is extremely slow without agitation.

 

[seabass07]

The co2 "blanket" that killed them did dissipate. Just after they suffoced.

 

[seabass07]

Also if co2 did not disperse into the surrounding air, we would suffocate if we layed down on the floor from our own co2 release.

 

[ArcaneXor]

The co2 "blanket" that killed them did dissipate. Just after they suffoced.

Exactly. Just like the "CO2 blanket" will dissipate if the fermentor is left uncovered or you have a fan blowing into it. If you only uncover it for a short time and the air is still, the concentration of O2 at the beer surface will only increase a little. After you re-cap it with an airlock, it is once again progressively diluted by absorption into the beer (some of it is then taken in by the yeast), and continued off-gasing of CO2 from the liquid (if it is still saturated).

 

[seabass07]

Exactly. Its just important that people realize that it will dissipate and mix with the surrounding air if air is allowed in.

 

[muse435]

Exactly. Just like the "CO2 blanket" will dissipate if the fermentor is left uncovered or you have a fan blowing into it. If you only uncover it for a short time and the air is still, the concentration of O2 at the beer surface will only increase a little. After you re-cap it with an airlock, it is once again progressively diluted by absorption into the beer (some of it is then taken in by the yeast), and continued off-gasing of CO2 from the liquid (if it is still saturated).

I concur with what you are saying. I was speaking of a long term bulk aging where all gasses trapped inside of a "closed" system (closed in the since after fermentation is over there will be no more airlock activity). The other thing to remember, is we are talking about a micro environment. If we start trying to compare the atmosphere to the minimal head space in the carboy we will be neglecting certain elements (ie. temp, weather, land masses, thermal activities, etc.)

I will admit I know nothing of the case you are referring to, so it is hard for me to comment on it. However, I don't think anyone will (logically) argue that you cannot displace one gas with another. Now if you "fog" the carboy, or keg, with co2, then siphon beer under it, pushing most of the gas out of the container, you will be able to drastically reduce the residual O2. What ever O2 remains in the container will remain in the head space and mix (statistically) even.

 

[muse435]

The co2 "blanket" that killed them did dissipate. Just after they suffoced.

I love this quote because i don't know if I should laugh or shake my head. lol.

 

[Homercidal]

I think it's pretty elementary that O2 and CO2 will mix given enough time and the right conditions. I think it's pretty important for Homebrewers to realize this. That when we say "blanket" something with CO2, we're talking about creating a temporary barrier. The "Blanket" of CO2 in a fermenter will not stay there if you continually open and close the lid to check it. Each time you allow more O2 into the container and it mixes with the CO2, and eventually comes in contact with the beer.

Likewise, adding CO2 to a bottle, or carboy, is useful only if you can close it up again right away. It's meant to help minimize the contact time of the O2 during a transfer process only. Not as a means of keeping O2 out of the container permanently.

 

[gr8shandini]

A very good proportion, say 1/3, of homebrew entered in competitions is distinctly oxidized. Homebrewers have a tolerance if not a preference for oxidized beer. According to Fix and Bamforth, many consumers do do (think of the preference for import beers which are uniformly oxidized and/or skunked).

I've heard the same thing, but do you have a source for that stat and how does it match up with your personal experience (I believe you're a BJCP judge, right)? I've drank plenty of homebrew from myself and others and have yet to come across one that displays the flavors typically associated with oxidation. Of course, I could just be lucky enough to be enjoying the 66% of homebrews that are OK.

 

[Homercidal]

I've heard the same thing, but do you have a source for that stat and how does it match up with your personal experience (I believe you're a BJCP judge, right)? I've drank plenty of homebrew from myself and others and have yet to come across one that displays the flavors typically associated with oxidation. Of course, I could just be lucky enough to be enjoying the 66% of homebrews that are OK.

I would not be surprised at this number. I admit I may have a hard time picking this flavor out myself, I think that a good percentage of homebrewers aren't as careful as they should be in handling their beer during bottling.

A very small leak in a bottling wand, or too vigorous stirring can introduce a significant amount of O2 into beer.

Couple that with my suspicion that a lot of competition judges are trained to seek out and note ANY amount of any flaw, and it's not hard to imagine that oxidation is found that often. Since judging is a relatively new pastime for a lot of people, I imagine that there are a lot of new judges who are still trying to find their flavors.

 

[LVBen]

I get oxidation in all of my bottled beers. I might have to start purging the bottles with CO2 first.

 

[unionrdr]

Or use o2 barrier caps. I've used them for a few brews now. They def work.

 

[Mpavlik22]

I always cap on foam & use oxygen caps. Never had any issues I can report on

 

[LVBen]

I've only ever used oxygen absorbing caps.

 

[LVBen]

I use a bottle filler and I don't get any foam to cap on.

 

[Mpavlik22]

I use a bottle filler also. The last 2 inches in the neck I pour from above the top of the bottle. That causes the beer to foam then I cap immediately.

 

[unionrdr]

I just let the bottling wand fill till it comes up even with the top. swish an o2 cap in star-san, & place it on the bottle till I have 12 or so. Then go over them with the Red Baron. Perfect heads space every time,great beer flavors that improve a couple weeks longer than before!
I get only a trace of foam on the surface. No need to induce it. Commercial bottling machines do that only because of the speed they're run at.

 

[PseudoChef]

I just let the bottling wand fill till it comes up even with the top. swish an o2 cap in star-san, & place it on the bottle till I have 12 or so. Then go over them with the Red Baron. Perfect heads space every time,great beer flavors that improve a couple weeks longer than before!
I get only a trace of foam on the surface. No need to induce it. Commercial bottling machines do that only because of the speed they're run at.

Commercial machines do it because they are bottling beer that is already carbonated, not because of the speed. It is good to induce in this case to flush the bottles of any possible O2.

When you are bottling uncarbed beer with a bottle wand, even though the beer crests the top of the bottle, once you pull the wand out, O2 is going back in. However, this O2 should then be reabsorbed by the yeast once they start fermenting the priming sugar.

 

[unionrdr]

Commercial machines do it because they are bottling beer that is already carbonated, not because of the speed. It is good to induce in this case to flush the bottles of any possible O2.

When you are bottling uncarbed beer with a bottle wand, even though the beer crests the top of the bottle, once you pull the wand out, O2 is going back in. However, this O2 should then be reabsorbed by the yeast once they start fermenting the priming sugar.

That's called volume displacement. It gives the proper head space for our application. They fill those bottles so fast,they only stop for a second or two. You can't help but get some foam. Besides,I used to be able to fix my own machines (automation machines) that had to run like that. So I know something about them. I can see your point about force carb. It just comes down to taking advantage of something the machine would do at that speed anyway.
The o2 caps help absorb that little bit in the head space over a couple days,as I currently understand them. So it's all good. Just can't help making that observation after working with big machines for nearly 31 years.

 

[jrg42]

i don't doubt anything you have posted, but I think the key concept is that CO2 is constantly being produced during fermentation.

For your water and alcohol example. If you started with 50/50 water to alcohol and then stuck a water hose in there and left it on, the water % would eventually approach 99%. Sure you could likely never get rid of 100% of the alcohol, but practically, it would be all but gone.

By the time fermentation is complete, I would think that C02 is the predominant gas in a carboy.

 

[AnOldUR]

I've always wondered about the push on HBT for long primary fermentation by some of the same people who say that their air-locks never bubble. Once active fermentation is over, if not sealed, your vessel breathes in and out with changes in temperature and pressure. That O2 being introduced does not take long to disperse throughout the headspace. And being in a primary with the beer being exposed to a lot of surface area only compounds the situation.

The conditioning effects of the yeast cake only last a few days to a week after you've reached final gravity. If you have the capability to purge your secondary with CO2 and push with CO2, your beer is much better off bulk aging in a sealed secondary with minimal headspace. There is still plenty of yeast in suspension to handle further conditioning.

 

[muse435]

Once active fermentation is over, if not sealed, your vessel breathes in and out with changes in temperature and pressure...
...The conditioning effects of the yeast cake only last a few days to a week after you've reached final gravity. If you have the capability to purge your secondary with CO2 and push with CO2, your beer is much better off bulk aging in a sealed secondary with minimal headspace. There is still plenty of yeast in suspension to handle further conditioning.

Thats why I try and maintain a constant temperature, but I have no control on the barometric pressure. But I do agree with what you are saying.

On my current brew this is my plan, to try and purge an empty carboy w/ CO2, place a stopper w/ a tube and an air lock on it, then push the cider from the primary to the secondary using CO2

 

[muse435]

i don't doubt anything you have posted, but I think the key concept is that CO2 is constantly being produced during fermentation.

For your water and alcohol example. If you started with 50/50 water to alcohol and then stuck a water hose in there and left it on, the water % would eventually approach 99%. Sure you could likely never get rid of 100% of the alcohol, but practically, it would be all but gone.

By the time fermentation is complete, I would think that C02 is the predominant gas in a carboy.

Correct, I was referring to the secondary where there is no/little fermentation, therefore not introducing CO2 to purge any trapped O2.

 

[Homercidal]

I've always wondered about the push on HBT for long primary fermentation by some of the same people who say that their air-locks never bubble. Once active fermentation is over, if not sealed, your vessel breathes in and out with changes in temperature and pressure. That O2 being introduced does not take long to disperse throughout the headspace. And being in a primary with the beer being exposed to a lot of surface area only compounds the situation.

The conditioning effects of the yeast cake only last a few days to a week after you've reached final gravity. If you have the capability to purge your secondary with CO2 and push with CO2, your beer is much better off bulk aging in a sealed secondary with minimal headspace. There is still plenty of yeast in suspension to handle further conditioning.

In most cases, if people leave their fermenter alone, there is enough give in the airlock system to account for temp fluctuations. But I don't dispute your point that a sealed container would be best.

 

[gr8shandini]

I'm with Homer on that one. When I pull the airlock after cold-crashing, I can tell that it's holding a small amount of vacuum, so I doubt that there's much of a gas transfer on a day-to-day basis. Of course, that's with a 3-piece. An "S" type airlock might be a little more free breathing.

 

[PseudoChef]

That's called volume displacement. It gives the proper head space for our application. They fill those bottles so fast,they only stop for a second or two. You can't help but get some foam. Besides,I used to be able to fix my own machines (automation machines) that had to run like that. So I know something about them. I can see your point about force carb. It just comes down to taking advantage of something the machine would do at that speed anyway.
The o2 caps help absorb that little bit in the head space over a couple days,as I currently understand them. So it's all good. Just can't help making that observation after working with big machines for nearly 31 years.

I'm not trying to argue semantics here, but pour, quickly (as your argument) a flat beer side by side with a carbed beer and tell me how much foam each gives. Speed is a miniscule factor compared to the carbonation of the beer, hitting various nucleation points in a bottle.

 

[unionrdr]

My point was strictly in regard to commercial applications only. The HB part is just my personal observations. As I said,automation equipment has many things in common that can't be avoided entirely.

 

[Mpavlik22]

The conditioning effects of the yeast cake only last a few days to a week after you've reached final gravity. If you have the capability to purge your secondary with CO2 and push with CO2, your beer is much better off bulk aging in a sealed secondary with minimal headspace. There is still plenty of yeast in suspension to handle further conditioning.

+100 I completely agree with this. Most people will argue this point. But I stand behind ya.

 

[bovineblitz]

i've always though that if the airlock is removed after fermentation is complete, there is no 'co2 blanket'. It only exists if fermentation is active/the container is sealed after fermentation

 

[muse435]

If you have the capability to purge your secondary with CO2 and push with CO2, your beer is much better off bulk aging in a sealed secondary with minimal headspace. There is still plenty of yeast in suspension to handle further conditioning.

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