oxidation question

[walker111]

I brew double batches and keg . When I put a keg in keezer all is good and great beer flows. It seems the second keg that sits on a second co2 system in spare bedroom is becoming oxidized. It has happened a few times and always the second keg. These kegs can sit for some time , even a few months, but under pressure in a keg. I am miffed on this one. O2 getting in somewhere I assume. The degree of oxidation is lower but I notice it and smell it in a glass. All my beers are closed transferred . Any ideas?

 

[MaxStout]

With positive pressure inside, outside air shouldn't get in. Only thing I can think of is O2 impurities in your CO2. Even a small percentage of O2 could cause oxidation when under pressure.

Edit: is that 2nd keg connected via a longer gas line than the first? Maybe some air still in the lines got pushed into the keg when you first turned on the CO2?

 

[walker111]

Thanks for your reply. That was a thought of mine. It has happened to 3 kegs in the past year. I have had oxidation prior in a few cases but this was years ago and before I closed transfer.

 

[marc1]

Aging is going to happen faster at room temp than fridge temp. Are the ones in the spare room refrigerated?

Maybe there's a point in your process that isn't ideal and is allowing more O2 in? Seems like you're good enough for the time it takes to use up the first keg, so it might be a smaller problem that's causing the long term storage issues.

Is your cold side completely sealed from yeast pitch to consumption? If not, look to the places where it's open for improvement. How are you purging your serving kegs?

 

[day_trippr]

"Unprotected" cold crashing before kegging?

Cheers!

 

[camonick]

What material is your gas tubing made from. Switching to EVABarrier might make a noticeable difference.

 

[doug293cz]

What material is your gas tubing made from. Switching to EVABarrier might make a noticeable difference.

This is good advice. Even though there is positive CO2 pressure in the gas line, O2 will still diffuse into the line, because the CO2 pressure does not affect the internal O2 partial pressure, and it's the difference in O2 partial pressures that drives O2 into the gas line.

Another thing you could do is disconnect the gas line after the beer has been carbonated. Then you would only have to worry about O2 diffusing into the gas line during the carbonation period, so less O2 overall.

Brew on

 

[balrog]

IF they sit in another room, I am thinking they are not on a gas tank line but literally sitting there.
Makes me think more the temperature is accelerating the process with these extra kegs that the chilled kegs don't see.

 

[walker111]

Hi all
Thanks for all who chimed in. The kegs not in keezer sit in spare bedroom in basement on a second co2 system at generally 20 psi as this room hovers around 16-18 degrees. I keep this room on a heater when fermenting. They sit in this condition until one in keezer is done and I move it over. Closed transfers for all beers and only time not in closed off system is when I dry hop and make sure to do this when there is fermenting still taking place . Fermonsters will lids I adapted with gas and beer posts.
I don't cold crash. I have but not these beers in question. The gas lines on second system are about 4 ft in length. The beer line tubing name escapes me right now and I am not at home. Bevex 3/16 maybe????

 

[lumpher]

Are you burping your kegs when you first carbonate them?

 

[tracer bullet]

I'd consider getting the beer into the keg via your closed loop, probably doing the "purge liquid out of it with CO2" thing first. Then do a quick force carb - I roll mine on the floor at about 15psi for ~ 10 minutes until no more gas will go in (I stop hearing it go through the regulator). After that unplug it from the CO2 and let it sit, carbed, and totally closed. I'm agreeing w/ an earlier post you might have O2 going in through that line you have connected. Even under CO2 pressure the O2 will work its way in.

Time isn't helping either of course so the less O2 you can get in up front the better!

 

[balrog]

I agree w unhooking CO2 from sitting kegs.

 

[marc1]

How are you purging your kegs?

 

[DuncB]

Depending on the beer you are brewing you could just prime that second keg and leave it to condition. The yeast would use up any oxygen that had got in there during your process.
You wouldn't keep carbonating a bottled beer once sealed after all.

Not sure why your sealed keg needs to stay on CO2; as mentioned by others it could just introduce tiny amounts of oxygen that will cause you trouble.
Other things to consider would be preventative measures for that keg such as sod met, ascorbic acid. There's been plenty about this recently and seems to be a brewing hot potato for a while now.
https://www.homebrewtalk.com/threads/vitamin-c-the-game-changer.698328/

 

[Bassman2003]

I would add a few things:

EVA Barrier tubing is great. Used with the Duotight system it is the best homebrewers can do.

Bottled CO2 gas that we have access to includes O2 gas. It is just a sad reality. Pure CO2 is special lab grade or is produced by yeast.

Try spunding or keg priming instead of using bottled CO2 to carbonate. Only use the bottle for serving.

 

[walker111]

After I transfer closed, I bup the keg 3-5 times while the gas is hooked to purge. Prior to the transfer, after the keg is cleaned I leave 1/3 full of starsan and use co2 to push this out and emplty the keg.
Looks like I am leaving them on the co2 too long. Maybe I will try to carb these kegs up for a week and disconnect and let them condition at room temperature.

 

[DuncB]

I'd fill the keg completely and then purge the starsan out ideally with ferment gas if not CO2 and then divert your gas from your ferment thru the keg to wash away as much O2 as possible.
You'll probably get some slow conditioning over a few months with some yeasts, especially English ale types that can keep munching away albeit slowly for a long time.
After all if it's not carbed enough when you crack the keg you can always force it then.

 

[day_trippr]

Bevex 3/16 maybe????

Probably Bevlex 200 solid PVC tubing as it was/is pretty much been the industry standard budget beer line for decades.
As PVC it's not much of a block against O2 permeation...

Cheers!

 

[Bassman2003]

These are complicated procedures. "Closed Transfer" can mean different things to different people. For your use case, closed transfer should be complete O2 free environment to another complete O2 free environment. Research and experience has shown the burping technique is not as good as we want it to be. So the best way is to hook the keg up to your fermentation gas output (natural CO2 purging) or to do a full liquid purge.

One can get anal about the O2 ingress but depending on how long your beers sit in the keg, it can make or break some beers. Cold side practice is very important.

 

[walker111]

Thanks for that Day Tripper.

 

[marc1]

After I transfer closed, I bup the keg 3-5 times while the gas is hooked to purge. Prior to the transfer, after the keg is cleaned I leave 1/3 full of starsan and use co2 to push this out and emplty the keg.
Looks like I am leaving them on the co2 too long. Maybe I will try to carb these kegs up for a week and disconnect and let them condition at room temperature.

Looks like you are keeping O2 out everywhere except in the keg you are transferring to.

I think purging with fermentation gas is the easiest method - hook up gas out from your fermenter to liquid in on your keg, then gas out from that to the liquid in on your second keg, then gas out on that to a spunding valve. You can keep pressure really low at first, and then turn it up when there's a few points to go to carbonate.

To purge with your CO2 tank, you need 13-15 purges at 30PSI. Kind of wasteful on an empty keg, not too bad on headspace after dry hopping.

As we've already established, these things aren't causing you noticeable short term problems, but long term stability issues.

 

[balrog]

Hook up fermenter to blow through keg that will contain beer eventually, as per @marc1 suggestion to fully purge a keg with fermentation gas.

 

[DuncB]

Although you will get oxygen ingress diffusion through those lines by the look of them.

 

[Beermeister32]

I’d let the second keg naturally carbonate with a 4-4.3 ounce charge of priming corn sugar. That will consume any stray O2 in the keg. Also add 1 teaspoon ascorbic acid dissolved in pre-boiled water at this time. Make sure to purge your keg 15 cycles with CO2.

 

[jnecessary]

Agree with Beermeister32, use sugar to carb the second keg that sits at room temp. Save gas and limit O2.

 

[superiorsat]

If time for brewing is not a factor instead of double batching and having a keg sitting around at room temp for a month or more just brew a batch at a time. You mentioned that you have cold crashed at some point just not on these so that makes me think you have a refrigerated area big enough to hold 2 fermonsters since you double batch. If you are on a good schedule you can have one carbed and ready before the other keg blows. I like variety to much to drink the same beer over and over. I rarely drink the same beer all night let a lone for months and months. All good advice above, just figured I throw in my 2 cents.

 

[RyPA]

To those recommending/have knowledge on EVAbarrier -- Can oxygen make its way through the red CO2 line?

This is what I'm using

 

[bwible]

Or a silly question - if you are brewing double batches, by that I assume you mean 10 gallon batches, and the second keg sits for a very long time, as in months, then why do you feel the need to brew double batches and have one keg sit so long, resulting in this issue?

 

[Bassman2003]

Yes, the PVC tubing is not as good as the EVA barrier tubing.

 

[IslandLizard]

Prior to the transfer, after the keg is cleaned I leave 1/3 full of starsan and use co2 to push this out and emplty the keg.

That method leaves the keg 1/3 filled with Starsan, and 2/3 filled with air, 21% of that being Oxygen. That translates to 14% (a volume of 3 quarts) in that keg is pure oxygen (!).

One of the better methods of 100% pre-purging that keg, is to fill it all to the way to the brim,* set the lid, and purge all the Starsan (or water) out, you'll get a keg that's 100% filled with CO2.
The essence is, the lid remains on the keg until the next cleaning. You'd fill the keg through the liquid out post with a QD attached to your transfer hose.

* Filling to the brim includes a few small details to also remove the small amount of air left under the lid and gas dome.

Then, a closed transfer from fermenter into the 100% pre-purged keg will prevent your beer being exposed to any, or as little as possible air (O2 being the bandit to avoid).

 

[Jim R]

I agree with others that this is a whole process issue and not a simple tubing issue. I would go back and look at everything in the process. I would consider pressure fermentation in a sealed fermenter, purging the Star San filled kegs with fermentation CO2, then pressure transfers and storage in a refrigerator with just an occasional hookup of CO2 to maintain carbonation. This is about the best anyone could do for longer storage.

 

[VikeMan]

I brew double batches and keg . When I put a keg in keezer all is good and great beer flows. It seems the second keg that sits on a second co2 system in spare bedroom is becoming oxidized. It has happened a few times and always the second keg. These kegs can sit for some time , even a few months, but under pressure in a keg. I am miffed on this one. O2 getting in somewhere I assume.

Unless you have gone to considerable lengths to exclude it, the oxygen is already in your kegs. The difference is temperature. Staling, like most chemical reactions happens faster at higher temps. To estimate the difference, you can apply a rule of thumb (Arrhenius Law) that states that reactions happen 2-3 times faster for each 10C increase in temperature. Assuming 3x for each increase of 10C, a 10C increase would reduce your shelf life by 67%. A 20C increase would decrease your shelf life by 89% (i.e. the beer would stay "fresh" only 11% as long).

I’d let the second keg naturally carbonate with a 4-4.3 ounce charge of priming corn sugar. That will consume any stray O2 in the keg.

That would certainly take care of some of the oxygen. But as many IPA bottlers have discovered in a quite dramatic way, not all of it, unless measures are taken to minimize the starting O2. Fortunately (for keggers), that's easier to do in a keg than a bottle.

Large commercial breweries target dissolved O2 limits in low parts per billion at packaging, even for bottle conditioned beers. A couple of pro anecdotal tidbits:

John Mallet (Bells) said that the yeast will use about a third of the headspace O2. (Bells also CO2 purges and caps on foam, so one would have to assume John is talking about a much smaller amount of starting O2 than a homebrewer would typically get in the headspace.)

Garrett Oliver (Brooklyn) said "Yeast can remove small amounts of dissolved oxygen from beer, but very little from the bottle headspace air, which means these benefits will only attain to breweries using sophisticated brewing methods and very good packaging equipment."

 

[doug293cz]

That method, leaves the keg 1/3 filled with Starsan, and 2/3 filled with air, 21% of that being Oxygen. That translates to 14% (a volume of 3 quarts) is that keg is pure oxygen (!).

One of the better methods of 100% pre-purging that keg, is to fill it all to the way to the brim,* set the lid, and purge all the Starsan (or water) out, you'll get a keg that's 100% filled with CO2.
The essence is, the lid remains on the keg until the next cleaning. You'd fill the keg through the liquid out post with a QD attached to your transfer hose.

* Filling to the brim includes a few small details to also remove the small amount of air left under the lid and gas dome.

Then, a closed transfer from fermenter into the 100% pre-purged keg will prevent your beer being exposed to any, or as little as possible air (O2 being the bandit to avoid).

I agree with others that this is a whole process issue and not a simple tubing issue. I would go back and look at everything in the process. I would consider pressure fermentation in a sealed fermenter, purging the Star San filled kegs with fermentation CO2, then pressure transfers and storage in a refrigerator with just an occasional hookup of CO2 to maintain carbonation. This is about the best anyone could do for longer storage.

If you have a leak tight fermenter, there is no need to liquid purge the kegs. Just feed all the fermentation CO2 thru the (initially air filled) keg to be purged, with an airlock or spunding valve on the gas post of the keg. This will get the residual O2 in the keg below 5 ppb (parts per billion.)

Brew on

 

[walker111]

Wow! I did not check in for a day and lots of response.
Double batch does mean 10 g for me and I am going to stick to that as like many of you sometimes finding the time to brew is a concern. I had a stockpile in my system and hence why there was so much beer around.......... usually not a big problem!!!!
I see that I have too much o2 in the empty keg getting the transferred beer. I clean good and when I purge out the starsan I only keep 1/2 to 1/3 in there as I thought I would be wasting so much co2.
This is same method for the first keg in the double batch but seems the second one sitting around develops the issue.

I also don't have enough space to keep the kegs colder other than the 4 tap keezer I built.

I hear people say to purge /burp the keg 15 times after it is kegged to rid 02. I probably only do 5 or so.
I can fix easy with the input given here. I have a few empty kegs right now and will re clean a few and fill with starsan and and try a natural purge coming of a fermenting beer to purge the starsan out of the available keg and use that keg when I package the beer ....

Could also try priming a keg with dextrose and let it condition like some have pointed out.
Thanks to you all I have some options and also know there is no need to keep the gas for so long on those kegs sitting.
Much appreciated.

 

[Bilsch]

If you have a leak tight fermenter, there is no need to liquid purge the kegs. Just feed all the fermentation CO2 thru the (initially air filled) keg to be purged, with an airlock or spunding valve on the gas post of the keg. This will get the residual O2 in the keg below 5 ppb (parts per billion.)

We need a 'double like' button on this forum for posts such as this where one just isn't nearly good enough.

 

[Bassman2003]

I hear people say to purge /burp the keg 15 times after it is kegged to rid 02. I probably only do 5 or so.
I can fix easy with the input given here. I have a few empty kegs right now and will re clean a few and fill with starsan and and try a natural purge coming of a fermenting beer to purge the starsan out of the available keg and use that keg when I package the beer ....

Glad this thread is helping. I just wanted to clarify a few things:

1) I would leave the burp approach in the dust. There are better ways!
2) When you fill with Starsan or other sanitizer you need to push it out under pressure. (bottled CO2) Using fermentation gas will not work and is a different approach. See #3
3) Daisy chaining empty kegs to your fermenation gas output uses empty kegs. Many people use two kegs, one hooked up to the fermentation blowoff and the 2nd hooked up to the 1st keg. The airlock goes on the last keg and the 1st keg is the one used for adding your beer to. But there are many permutations. In the end, it is pure CO2 that is free if your fermentation chamber allows for it.

 

[RyPA]

Have you tried fermenting/serving from the same keg? You can dry hop with magnets. I recently tried this and will likely continue doing it.

 

[odie]

If you are "burping" the keg a few times after filling it, the O2 in the keg headspace is minimal. Like a fraction of a percent. I would store the keg cold.

free air is only 21% oxygen. Before you pressurize the keg it's at 14.7 PSI sea level (0) gauge PSI). When you blast the keg with CO2 to say maybe 60 PSI and then bleed the PRV, you have just expelled 80% of that air and only 21% of that air it's O2. Leaving about 4% O2. Burp it again and another 80% of the oxygen is expelled down to under 1% in the head space. Only takes a few times to get to 0.0?% oxygen left.

A little priming sugar will clean up any oxygen that remains. After a few days for the yeast to do it's thing, cold crash and store cold. I think that might fix your oxidation issues.

 

[walker111]

Thanks again all. Hope to brew saturday....... weather depending as it sits at -36 with windchill up here in the North country and I have time to put some advice here into practice.

 

[Panderson1]

Purge (burp) more. I always felt 3-5 times is not enough. I burp it 15-20 times lol. It's worth the $ (gas) to me.