Scrubbing Sulfur...

[Mute_Ant_Brew]

So making a wit style beer using a house culture I captured and built up. Second time fermenting with this culture but I went a little colder on the fermentation temp this time. Ambient temperature of ~61 F. The outside of the fermenter read at ~ 66 F from the stick on thermometer.

Anyway fermentation wound down after 4 days and I'm not sure what I was think but I transferred the beer to my severing keg to act as a secondary ferm vessel. Attached a gas line to the post with the open end in a jar of starsan.
The fermentation threw lots of sulfur smell and after a week in "secondary" the smell isn't coming off.

I just pitched a fresh batch of the house culture and put the beer in my ferm chamber at 70 F to hopefully help clean up the sulfur.

Any thoughts on whether this will work or if there is anything else I could do? Ideally I would have just left the thing in primary for several weeks but being past that option hopefully I can still turn this into a decent beer.

 

[VikeMan]

I just pitched a fresh batch of the house culture and put the beer in my ferm chamber at 70 F to hopefully help clean up the sulfur.

Any thoughts on whether this will work or if there is anything else I could do? Ideally I would have just left the thing in primary for several weeks but being past that option hopefully I can still turn this into a decent beer.

I'm not sure that adding yeast to already fermented beer is going to do anything to clean up sulfur.

Since this is already in a keg, you could run CO2 in through the liquid post while venting the keg.

 

[Jayjay1976]

Since this is already in a keg, you could run CO2 in through the liquid post while venting the keg.

I've read about this technique, super interested in how well it works and how long it takes.

 

[Mute_Ant_Brew]

I'm not sure that adding yeast to already fermented beer is going to do anything to clean up sulfur.

Since this is already in a keg, you could run CO2 in through the liquid post while venting the keg.

I suppose my concern with this method would be losing any character the yeast had contributed to the beer, but that would still be better than drinking a beer that smells like eggs.

 

[dmtaylor]

All you need is time. Wait a couple more weeks, the sulfur should disappear without any special actions needed from the human.

 

[VikeMan]

I suppose my concern with this method would be losing any character the yeast had contributed to the beer, but that would still be better than drinking a beer that smells like eggs.

If you do decide to try it, use low pressure, like 3-4 PSI, and run it for maybe 30 seconds at most, while venting. If you get foaming/spitting, back off. Smell, and if necessary, try again later.

Others may have different "recipes" for this.

 

[RPh_Guy]

The fermentation threw lots of sulfur smell and after a week in "secondary" the smell isn't coming off.

I cover the causes of hydrogen sulfide and methods for removing it in detail on my wiki:
https://***************.com/wiki/Hydrogen_sulfide
Your best bet is a little bit of oxygen exposure (e.g. "aging"), or you could try some copper.

Yeast exposure has been shown to help remove it BTW.

 

[VikeMan]

Your best bet is a little bit of oxygen exposure (e.g. "aging")

I almost posted this, but couldn't bring myself to recommend intentionally adding O2 to finished beer.

 

[Jayjay1976]

...the sulfur should disappear without any special actions needed from the human.

B-But after my hop spider, the human is my favorite piece of brewing gear!

 

[day_trippr]

lol!

Anyway...I'm thinking "huge underpitch that's still finishing up".
Any gravity readings to work with here?

Cheers!

 

[Jayjay1976]

lol!

Anyway...I'm thinking "huge underpitch that's still finishing up".
Any gravity readings to work with here?

Cheers!

I agree, this is like a massive underpitch.

 

[Jocky]

All you need is time. Wait a couple more weeks, the sulfur should disappear without any special actions needed from the human.

Would you leave in the keg sealed, and is it better warm rather than cold?

I'm unsure whether there's a need to let the sulphur be released as gas or whether it attaches to yeast and drops out. Maybe a bit of both.

 

[Mute_Ant_Brew]

I will grab my gravity readings later but I'm fairly certain it wasn't an under pitch. I over built the starter to save some for later brews. Three steps.
For the gravity, and I can confirm later with my notes, I believe i started around 1.050 and was at 1.009 at transfer.

 

[dmtaylor]

Would you leave in the keg sealed, and is it better warm rather than cold?

I'm unsure whether there's a need to let the sulphur be released as gas or whether it attaches to yeast and drops out. Maybe a bit of both.

Yes, leave it in the keg. Better warm than cold. You can try purging and venting with extra CO2 but I'm not convinced it matters. I bottle all my beer and the sulfur ALWAYS goes away by itself after a few weeks.

 

[Jocky]

Yes, leave it in the keg. Better warm than cold. You can try purging and venting with extra CO2 but I'm not convinced it matters. I bottle all my beer and the sulfur ALWAYS goes away by itself after a few weeks.

Cool, thanks.

 

[Vale71]

Hydrogen sulfide doesn't get scrubbed by yeast. CO2 or N2 scrubbing is used in the industry via specialized equipment but just blowing CO2 through a keg will not be very effective and waste a lot of gas.
The good news is H2S is a reducing agent and it will bind to oxidized compounds thus removing both its own foul smell as well as the effects of oxidation on beer. I wouldn't recommend purposefully oxidizing the beer though as it's very easy to go overboard and do more damage than good. Besides that, homebrewed beer is on average already quite oxidized so there's really no need to go and make things worse. Just let the beer mature, the warmer the better (and faster), and the stench will eventually go away as the H2S concentration drops below detectability thresholds.

 

[RPh_Guy]

Hydrogen sulfide doesn't get scrubbed by yeast.

It does.
https://***************.com/wiki/Hydrogen_sulfideSee Oka et al 2008

H2S is a reducing agent and it will bind to oxidized compounds

It reacts directly with oxygen.

 

[dmtaylor]

Hydrogen sulfide is reactive with lots of stuff. That's why it will disappear all by itself given time. Source: Well I'm a chemical engineer, so.

 

[RPh_Guy]

Which compounds in beer react with H2S?

 

[dmtaylor]

Which compounds in beer react with H2S?

H2S is particularly reactive with any metals, including stainless steel as well as the often touted copper. Any trace metals in the beer will eventually react with it. I wonder if even the bottle caps in bottled beer can react with some of it. And if you keg, well, you should be good to go.

It will also react with some plastics, but I'm not sure how significant an impact this might have.

Beyond that, any surviving yeast, whether intentional or wild, will reabsorb much of the H2S over time.

Just a couple of good sources I found on Google:

https://www.ncbi.nlm.nih.gov/pubmed/18930001
https://www.morebeer.com/articles/sulfur_compounds_in_beer

 

[RPh_Guy]

H2S is particularly reactive with any metals, including stainless steel as well as the often touted copper. Any trace metals in the beer will eventually react with it. I wonder if even the bottle caps in bottled beer can react with some of it. And if you keg, well, you should be good to go.

It will also react with some plastics, but I'm not sure how significant an impact this might have.

Beyond that, any surviving yeast, whether intentional or wild, will reabsorb much of the H2S over time.

Just a couple of good sources I found on Google:

https://www.ncbi.nlm.nih.gov/pubmed/18930001
https://www.morebeer.com/articles/sulfur_compounds_in_beer

Copper has variable effects depending on when it is present. When copper is present during fermentation (e.g. after using a copper chiller), it's been shown that higher levels of hydrogen sulfide are produced. The same is true for stainless steel. It's postulated that yeast increases H2S production as a defense against heavy metal toxicity. Therefore using a copper chiller really isn't doing you any favors.
Here's an example study regarding stainless steel:
https://www.nrcresearchpress.com/doi/abs/10.1139/w99-010
I have more references if you want them, many in my article.

Copper added after fermentation (and after separation from the yeast) helps remove H2S. Stainless steel does not.

Unfortunately that article on MoreBeer contains a lot of misinformation.

 

[Mute_Ant_Brew]

TLDR: The sulfur is gone with minimal human involvement.

Just an update on the beer for anyone following along still.
I sat it in the ferm chamber at 70 this whole time after the yeast re-pitch.
Last night I checked on it and there was not any noticeable sulfur smell. A 70 degree uncarbed pour was actually fairly pleasant. It's carbing and chilling now.

I don't know if the re-pitch did anything to help but it didn't hurt anything. My guess would be the yeast that was in suspension would have been enough along with the additional aging.

I heard while listening to one of the Brewing Network podcasts that the addition of coriander can contribute to the sulphur smell during fermentation. Anyone experience that as well? This beer, being a wit, had an addition of coriander seed.

Thank you for the replies and the linked additional reading on the subject.

 

[VikeMan]

I heard while listening to one of the Brewing Network podcasts that the addition of coriander can contribute to the sulphur smell during fermentation. Anyone experience that as well?

I guess it's possible.

I just kegged a beer that used a lot of (Indian) Coriander (several ounces) in a 5 gallon batch, added at various times in the process, and I didn't note any sulfury aroma.

 

[RPh_Guy]

I don't know if the re-pitch did anything to help but it didn't hurt anything.

Opening the vessel introduced oxygen.

I heard while listening to one of the Brewing Network podcasts that the addition of coriander can contribute to the sulphur smell during fermentation. Anyone experience that as well?

Only if it's coated with a significant amount of sulfur or copper preservative.

 

[Tripod - The Real Tripod]

Yes, leave it in the keg. Better warm than cold. You can try purging and venting with extra CO2 but I'm not convinced it matters. I bottle all my beer and the sulfur ALWAYS goes away by itself after a few weeks.

Follow-up question for @dmtaylor (or anyone with experience) - I assume while we are leaving this in the keg it needs to be under at least minimal pressure...otherwise, 'undesirables' could be introduced and contaminate the keg. Just wanted to clarify that smell will 'drop' (in the sealed keg) by itself and doesn't need to actually 'vent out' (which is more of a 'scrubbing' technique).

Also - what's the preferred temperature to let this sit? @ 75* in my house, @ 63* in my fermentation chamber, or @ 100*+ in my garage?

 

[dmtaylor]

Follow-up question for @dmtaylor (or anyone with experience) - I assume while we are leaving this in the keg it needs to be under at least minimal pressure...otherwise, 'undesirables' could be introduced and contaminate the keg. Just wanted to clarify that smell will 'drop' (in the sealed keg) by itself and doesn't need to actually 'vent out' (which is more of a 'scrubbing' technique).

Also - what's the preferred temperature to let this sit? @ 75* in my house, @ 63* in my fermentation chamber, or @ 100*+ in my garage?

Good idea to keep under at least a little pressure. 63 F would be a good temperature to store it at. Even 75 F wouldn't be terrible. Not 100 F!

 

[mamajack]

I'm really thankful for this thread, in particular @dmtaylor 's article ref link above. I brew small batch and so far only ales, but I made a Cali Common with SF lager yeast having no idea that lager yeasts throw sulfur. I kept running around the house trying to find a gas leak!
It took a really long time to off gas the sulfur, even with a warmish fermentation (i like fruitiness in this one) and just 4.6% ABV, perhaps because I bottle and don't keg. The beer ultimately tasted great but it took months. I was looking for a way to scrub S02, but it seems the best remedy is patience.

 

[z-bob]

Nobody mentioned it, probably because OP's beer was in a keg, but you might try gently stirring the beer with a piece of copper tubing or #6 (etc) bare copper wire.