Talk me off the ledge

[bluehende]

I have a very sour smell coming from my fermenter. This is a remake of a very successful blonde ale. I used 2 row with a bit of vienna. Cascade hops bittered to about 22 IBU. BIAB 5 gallon batch. I pitched a washed yeast from an IPA....US-05 about 3rd generation. The pitch did not smell heavily of hops. I had activity at about 12 hrs and it was humming along at 24. Swamp cooler covering 2/3 of the fermenter was at 60 degrees. Ambient around 65 +- 2. At day 4 1/2 fermentation seemed to be completed.

So today I notice a sour smell coming from the airlock. I have noticed something like this smell a bit from yeast starters, however this was big. I opened it up and took a gravity reading and it is within a few points of done if not done at the five day mark. Nothing looked too out of the ordinary. A bit of the dark krausen that sticks to the side of the bucket and what looks like yeast floats. Nothing fuzzy looking.

Has anyone noticed a sour smell at this point? I find it hard to believe that an infection would have soured this much in a few days. My plan is let it go the two weeks I had planned and hopefully bottle. Please tell me this is normal and it will clear up in the next week.

 

[hlm123]

When you take a gravity reading you might as well take a sample to taste to see if it's "ruined". Chances are very high that it's just yeast doing their thing, i.e., giving you carbon dioxide to breathe in.

 

[tootal]

Agreed, there's a lot of things produced by the yeast that it needs to clean back up. Let it sit another week and taste it. Might get the temp up to around 70 to help with the clean up.

 

[BBL_Brewer]

When you take a gravity reading you might as well take a sample to taste to see if it's "ruined". Chances are very high that it's just yeast doing their thing, i.e., giving you carbon dioxide to breathe in.

We breathe oxygen, not carbon dioxide. We breathe out carbon dioxide as a metabolic waste product, as does the yeast during anaerobic respiration.

OP. I wouldn't worry unless the beer tastes bad. If everything looked normal in the fermentor, you should be fine. You might want to stop reusing that yeast though if you think it might might be getting contaminated.

 

[hlm123]

We breathe oxygen, not carbon dioxide. We breathe out carbon dioxide as a metabolic waste product, as does the yeast during anaerobic respiration.

Thanks for that.

 

[bluehende]

You guys have me with one foot back in the window. I should have tasted it when I had it open. I sanitize my hydrometer and put it straight in the bucket. And to be honest the smell did not make my mind go immediately to "let's taste that". I was a research biochemist and would say the smell was definitely what I call an anaerobic smell. I have 9 days til a vacation so it has that long to clean up.

 

[hunter_le five]

JUMP! JUMP! JUMP!

 

[bluehende]

JUMP! JUMP! JUMP!

Feel the love!!!!

 

[fuzzy2133]

You guys have me with one foot back in the window. I should have tasted it when I had it open. I sanitize my hydrometer and put it straight in the bucket. And to be honest the smell did not make my mind go immediately to "let's taste that". I was a research biochemist and would say the smell was definitely what I call an anaerobic smell. I have 9 days til a vacation so it has that long to clean up.

If you have any concerns just bottle it and let us know. Plenty will volunteer to properly dispose of it for you.

 

[Setesh]

US-05 is my house strain. I haven't figured out why yet, but once in a while it gives off a sour smell and flavor that conditions out. It has taken as little as 1 week and as long as 3 to condition out, but it always goes away. The sour smell doesn't last that long, maybe a week, but the flavor is more persistent. I can only assume it is down to husbandry on my part. I will have made the same beer lots of times before and all of the sudden a batch does this sour thing, then the next batch is normal again. I use temp controlled chambers, I always oxygenate the same amount of time based on gravity, and I always use the same pitching calculator. I'm not sure what I'm doing to stress the little guys, but since the sour note conditions out I'm not too worried about it. You make it sound like it smelled pretty iffy, so maybe it's not the same thing. What I get is a clean sour smell and flavor, like lacto produces but just the slightest hint of it. This decreases over the next few weeks. When it's gone I keg the beer.

My opinion is to let it sit for a couple of weeks then try another sample. If the sour is gone then move on to packaging. If it is almost gone then wait another week. If it gets worse then it is contamination and nothing can be done.

 

[bluehende]

US-05 is my house strain. I haven't figured out why yet, but once in a while it gives off a sour smell and flavor that conditions out. It has taken as little as 1 week and as long as 3 to condition out, but it always goes away. The sour smell doesn't last that long, maybe a week, but the flavor is more persistent. I can only assume it is down to husbandry on my part. I will have made the same beer lots of times before and all of the sudden a batch does this sour thing, then the next batch is normal again. I use temp controlled chambers, I always oxygenate the same amount of time based on gravity, and I always use the same pitching calculator. I'm not sure what I'm doing to stress the little guys, but since the sour note conditions out I'm not too worried about it. You make it sound like it smelled pretty iffy, so maybe it's not the same thing. What I get is a clean sour smell and flavor, like lacto produces but just the slightest hint of it. This decreases over the next few weeks. When it's gone I keg the beer.

My opinion is to let it sit for a couple of weeks then try another sample. If the sour is gone then move on to packaging. If it is almost gone then wait another week. If it gets worse then it is contamination and nothing can be done.

This is the exact thing I wanted to hear. A clean lacto smell is dead on. This is pretty strong as opposed to faint. I have no idea of the taste. I will actually taste it at 15 days and determine whether to bottle or not. If it still has some sour notes I will let it go another week while on vacation. If it is an infection it should be obvious by then. The smell and taste should get stronger as opposed to going away if I have a problem. Like you said, nothing at all different in this fermentation. Oxygenation, temp (not controlled but swamp cooled), pitch rate, wort OG were all pretty much the same. I will certainly update as we go. I can only assume the yeast are feeling the pressure I am. I had this beer at my son's rehearsal dinner and it was a huge hit. Now I have the pressure to repeat it and not disappoint the family. They are placing their orders for various family functions.

 

[Setesh]

I had this beer at my son's rehearsal dinner and it was a huge hit. Now I have the pressure to repeat it and not disappoint the family. They are placing their orders for various family functions.

Gotta love that feeling of pride! Congrats We'll wait to hear how it turns out.

 

[Heavywalker]

We breathe oxygen, not carbon dioxide. We breathe out carbon dioxide as a metabolic waste product, as does the yeast during anaerobic respiration.

It sounds like you are suggesting that the human body is incapable of inhaling CO2.

If the yeast are producing Co2 and you take a stiff from the fermentor you are most definitely breathing in CO2.

 

[bluehende]

9 days later......

I opened it up and the smell is much less. It is still there but now it does not dominate. I took a sample and tried it. I believe it has little to no sour taste. With the smell it would be hard to not taste it a little. I could be convinced that it is only in the smell. I went ahead and primed and bottled it. Hopefully the yeast in the bottle will finish off cleaning it up. I will try it in two weeks to see. If it is not pleasant yet I have patience. The July 4th crowd will have to understand that beer is a living thing and does what it wants to.

 

[j1n]

Next time do a wort stability test. You take some wort and put it in a sanitized mason jar or some type of vessel. Leave it there covered in sanitized foil for a few days (no yeast is added). If there isn't any fermentation in the jar after 72 hours @ 80 degrees then you should be good to go. The test is to measure the level of contamination in the wort. the fermentation is from the wild yeast and bacteria in the wort.

 

[pablosbrewing]

Sounds to me like it could be acetylaldehyde.

Raise temp of primary to 72F for 3 days after main fermentation is completed and the yeast will clean house.

 

[bluehende]

Sounds to me like it could be acetylaldehyde.

Raise temp of primary to 72F for 3 days after main fermentation is completed and the yeast will clean house.

I think you might be right. Green apples is not what would come first to mind with the smell. On further research a cidery taste is noted. This is close. The fact that it is getting better is further evidence. I hope this is it as it should clean up in the bottle. the big question now is why? I had pretty good control of temp. No chamber, but the swamp cooler stayed steady within a degree or two of 60. The fermentation was not a run away so shouldn't have raised the temp too much. The yeast pitch could have been slightly underpitched. I used 1/3 to 1/5 of a yeast cake from a 3% abv bigger beer. I had bubbles in 8 to 16 hrs. I hate to chalk it up to random. Hard to fix random.

 

[pablosbrewing]

I think you might be right. Green apples is not what would come first to mind with the smell. On further research a cidery taste is noted. This is close. The fact that it is getting better is further evidence. I hope this is it as it should clean up in the bottle. the big question now is why? I had pretty good control of temp. No chamber, but the swamp cooler stayed steady within a degree or two of 60. The fermentation was not a run away so shouldn't have raised the temp too much. The yeast pitch could have been slightly underpitched. I used 1/3 to 1/5 of a yeast cake from a 3% abv bigger beer. I had bubbles in 8 to 16 hrs. I hate to chalk it up to random. Hard to fix random.

For US-05, lower temps produce acetylaldehyde and diacetyl. Not really defects of the yeast, they just didn't finish their cycle. The best practice to seems to be allowing the fermenter to rise to room temp for several days in primary after active fermentation is completed.

65-68F seems to be the best fermentation temp range to shoot for. I now tend to stay in primary at least 2 weeks, 3 weeks for higher OG, so even if I wander outside that range any off flavors are getting cleaned up.

 

[bluehende]

After two weeks in the bottle the beer is good. There may be a tiny bit of the sourness left. This could also be the power of suggestion as I smelled this for quite some time. Give it a couple more weeks and it may be a hit again.

 

[johngaltsmotor]

If you need a fresh pallet of a disinterested party I'll offer my services :fro: free of charge even