O2 removal from purging liquid in keg

[dustinstriplin]

One vector for cold side O2 ingress is in the starsan solution used to fill a keg before purging with CO2. There will be a small amount of starsan left over in the keg after pumping the keg dry with CO2. That left over star san will have dissolved O2 in it, which will inevitably cause oxidation in the final product, albeit, such a small amount will take a while to be noticeable. I'm not completely comfortable knowing that this O2 is present in my beer.

I could use some input on this idea I had. A way to remove the O2 from the starsan solution would be to add some crushed campden tablet. However, I don't know if I'd be causing more harm than good by doing this. Does anyone know if the campden tablet would react with starsan and give a less than desirable result?

Another solution, which I'm positive will give good results, is to fill the keg with boiling water, then pump that out. This is something I'm willing to do, but would rather not because of the effort and time involved in heating, then cooling.

Appreciate any other solutions as well as long as they address the removal of O2 introduced in this stage of kegging.

 

[doug293cz]

You could just use fermentation CO2 to push the StarSan out of the keg. After the liquid is almost all pushed out, the O2 in the residual StarSan will diffuse out into the empty keg space, and get carried away as CO2 continues to flush the keg.

Brew on

 

[dustinstriplin]

Great idea!

I also found this post, unfortunately after posting here, that has some solid advice - https://www.homebrewtalk.com/threads/on-purging-and-spunding.730532/#post-10337473

 

[PCABrewing]

I'm not completely comfortable knowing that this O2 is present in my beer.

What amount (PPM) of oxygen are you comfortable with?

 

[dustinstriplin]

What amount (PPM) of oxygen are you comfortable with?

0, I know it's not realistic.

 

[scrap iron]

An Iodine sanitizer will work, or I think they make a foamless version of Star San.
I just use regular Star San, dump it all out and hook up the keg to fermentation gas like Doug293cz said.

 

[mac_1103]

An Iodine sanitizer will work, or I think they make a foamless version of Star San.

I thought the concern was the dissolved O2 in the water used to mix up the sanitizer. This will affect any sanitizer - acid, iodine, foamy, foamless, etc.

 

[day_trippr]

Another solution, which I'm positive will give good results, is to fill the keg with boiling water, then pump that out.

I would be careful about this approach with a classic cornelius keg as it carries a risk of ungluing the keg bottom...

Cheers!

 

[dustinstriplin]

I would be careful about this approach with a classic cornelius keg as it carries a risk of ungluing the keg bottom...

Cheers!

I’ve never thought of that. I’ve done the boiling water in the keg thing every time I clean a keg that had a sour beer. I’ll have to keep that in mind from now on. Thanks!

 

[wdavis2003]

An Iodine sanitizer will work

Doesn't this have to completely dry before adding consumable liquids (beer) to the vessel? Or is that just best practice?

 

[Bobby_M]

There will be a small amount of starsan left over in the keg after pumping the keg dry with CO2.

If you cut your gas diptube very short, you can flip the keg upside down and vent the gas poppet.

 

[scrap iron]

Doesn't this have to completely dry before adding consumable liquids (beer) to the vessel? Or is that just best practice?

Yes, best practice is to let it dry. I used to use the Iodine thinking there would be less o2 after purging the keg with co2 than with Star San. I would hit it with a little co2, turn the keg upside down and blow out any Iodine left. I now, after learning the fermentation purge method on this site, just use regular Star San. I fill the keg then after it sits to sanitize just dump it back in my bucket for reuse. Then hook up the keg to the fermenter and let the ferment gas purge it. The ferment purge takes care of any Star San bubbles left in the keg.

 

[CascadesBrewer]

A way to remove the O2 from the starsan solution would be to add some crushed campden tablet.

I tried this recently when kegging an NEIPA. Did it have any impact? It is hard to say as I don't notice any oxidation issues with just purging a keg with a normal Starsan solution. I would have to check to see if I have info on how much I used.

There is this video about just purging the keg with water treated with Sodium Metabisulfite. I am not sure the guy actually uses enough to effectively scrub the oxygen or to act as a sanitizer. Sodium Metabisulfite in bulk is quite cheap, so I would not be opposed to using this method if it was effective. I am just not quite sure what the dosage should be to scrub the oxygen from 5 gallons of water.


I like the idea of using fermentation CO2 to purge a keg and I have done that. It just does not quite fit well with my process and my fermentation chamber.

 

[day_trippr]

I imagine the tricky part of using SMB is to get the dosage right as adding too much is going to leave some sulfur behind. I use Ascorbic Acid when kegging instead to suck up whatever my fermentation gas purging leaves behind and any incidental O2 from racking without worrying about lingering sulfurous notes...

Cheers!

 

[balrog]

I imagine the tricky part of using SMB is to get the dosage right as adding too much is going to leave some sulfur behind. I use Ascorbic Acid when kegging instead to suck up whatever my fermentation gas purging leaves behind and any incidental O2 from racking without worrying about lingering sulfurous notes...

Cheers!

How much?

 

[day_trippr]

1 teaspoon, dissolved in 30ml of warm water, then injected into the keg before racking the beer on top...

Cheers!