STRONG sulfur smell

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Wallachia

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Hello all,

Have a few brews under my belt, but have a problem I haven't seen before so I thought I'd post here.

My APA attempt from the weekend before last is still bubbling through the blowoff tube slowly after about 13 days. This wouldn't bother me so much, but yeast/trub cake I've pulled off the bottom and samples I've pulled from it smell STRONGLY of cabbage and sulfur, with a hint of green apple thrown in there for good measure. It's... a very off-putting odor. Which is a shame, because you can still smell the citrusy Mosaic hops behind that horrible smell.

I took a quick peek in the fermenter today with a flashlight, and nothing looks terribly out of the ordinary, normal looking yeast encrusted on the sides, still a bit of foam at the top.

Does this sound like just an unhealthy yeast pitch, an 'invisible' infection, or something else?
 
Yeast can kick out some really weird odors. What yeast strain are you using and how warm is the fermentation? Also, its best to leave the fermentor closed until its done and your ready for the next step.
 
Yeast can kick out some really weird odors. What yeast strain are you using and how warm is the fermentation? Also, its best to leave the fermentor closed until its done and your ready for the next step.

I'm using Wyeast WLP001 California Ale yeast, I made a 1 liter 1.040 OG yeast starter using a stir plate. I have kept my fermenter closed with the exception of gently opening it for a couple seconds today to see if there was a crust of mold or something (because of the strong, persistent smell).

Fermentation was actually a little lower temp than I'm comfortable with. Yeast is optimum around 68-73F according to White Labs, fermentation was sitting around 62F so I used an electric blanket (set low) and monitored the temperatures to get temperature of the fermenter around 66F to account for higher temp in the wort.
I don't have great temperature control yet, but I think I kept this one in the ballpark at least.

Should I take a gravity reading to see if it's even moving along?

EDIT: typos
 
Sounds like it could be dimethyl sulfide (DMS), which would stem from hot-side issues. If this is the case, it's already too late for this beer. In the future, make sure to boil for at least 60 minutes uncovered, 90 minutes with any significant amount of Pilsner malt in recipe. And cool the wort as quick as possible after boil end.

If it's yeast derived, then it's likely hydrogen sulfide (H2S). In which case, H2S is volatile, so letting the beer vent to atmospheric pressure (e.g. airlock) for another week or two should exhaust the remainder of the sulfur smell.

Let's hope it's the latter, not the former.

The green apple aroma is probably acetaldehyde, which is produced by the yeast. This won't diminish much if at all. The most common causes for this are fermenting at too warm of a temperature, poor yeast health, oxidation, and removing the beer from the yeast too soon.
 
Hey Tiber,

I did look around a bit at possible sources of Dimethyl Sulfide. This was a very light, very pale-malt intensive grain bill (about 13 lb pale 2 row, 1 lb munich) and I boiled for 60 minutes -- In the future, I'll step my recipes up to 90 minutes if they're this light.

I also read that there is some DMS production post-boil before cold crashing. I use a plate chiller, but I did use flameout hops with this recipe, so after flameout I had the hot wort covered for about 10-15 minutes. Do you think this could account for the sulfide production, or is it not significant enough??

As for the bit of green apple note, I can totally live with that, if the pungent simmered cabbage/old egg smell can be dissipated.

If not, I'm already plenty psychically prepared to dump this batch down the toilet and try again, this is a new recipe for me anyways; I'm more concerned about finding out what I did wrong :)
 
Hey Tiber,

I did look around a bit at possible sources of Dimethyl Sulfide. This was a very light, very pale-malt intensive grain bill (about 13 lb pale 2 row, 1 lb munich) and I boiled for 60 minutes -- In the future, I'll step my recipes up to 90 minutes if they're this light.
Probably a good idea. I boil all my beers for 90 minutes. First, I don't have to worry about DMS. Second, it adds consistency to my process. It also gives me a half hour to clean my MLT before I need to add hops to the boil.

I also read that there is some DMS production post-boil before cold crashing. I use a plate chiller, but I did use flameout hops with this recipe, so after flameout I had the hot wort covered for about 10-15 minutes. Do you think this could account for the sulfide production, or is it not significant enough??
It's possible, although I've never had issue when using whirlpool hops or doing a hop stand.

As for the bit of green apple note, I can totally live with that, if the pungent simmered cabbage/old egg smell can be dissipated.
I'd leave the fermentor vented with an airlock for another week or two and see if it dissipates. If it doesn't, then it's probably DMS and there's not a lot (at least that I know of) that you can do about it.

If not, I'm already plenty psychically prepared to dump this batch down the toilet and try again, this is a new recipe for me anyways; I'm more concerned about finding out what I did wrong :)
That's a good attitude. A small part of me dies every time I have to dump a beer. But all is not lost, so long that I learned a lesson about how to prevent future flaws!
 
Acetylaldehyde:
Chico yeast - US-05, WY-1056, WLP001 - cool temps and/or underpitching seem to increase acetylaldehyde, I stick in primary for 2-3 weeks now depending on gravity, with a rise to 70F for the last couple of days.

DMS:
  • What is your boil off rate, if it's below 8% or so that could be a cause.
  • Is it possible at all that you got 6-row (pilsner) malt?

edit: don't dump it! :)
 
'Lo,
Just a follow up in case anyone was still wondering:

I gave it another ~2.5 weeks, and the smell really didn't subside at all (it wasn't just 'sulfury', it almost burned the sinuses like brimstone, but didn't smell vinegary).

I dumped it, and I'm about to try again, having modified my recipe for account for a 90 minute boil, and using a (hopefully) stronger starter

Quick question: if I do flame-out hopping (this recipe calls for a whole 4 oz of flameout/whirlpool hops!) should I leave the boil vessel open for the ~10m of flameout hopping?
I've heard the DMS production from covering the boil kettle for that last 10m of flameout is fairly negligible, but I'm trying to nip this issue in the bud so it doesn't recur, I'd hate to throw another 7 oz of Mosaic out the window too! :)
 

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