Imperial Darkness - Issues?

[TestTickle]

I have been a big fan of Imperial Darkness for awhile. I use it for pretty much every dark-ish to dark beer that I brew. It starts and finishes pretty quick (?) and attenuates well.

Here's my problem. I have had a few bottle conditioned/aged brews in the past year that ended up over-carbed. The one thing they all had in common was that I used Darkness. I mostly keg, but still bottle when I am out of space in the keezer, when I want to age beer or when I brew something I don't want taking up a tap. I brewed a Scottish Ale back in September that was fantastic after a couple of months in the bottle, but I chilled and drank one today and it was over-carbed. Not a gusher, just over-carbed. I had the same thing happen with an imperial stout recently as well. They still tasted fantastic, just over-carbed. Milk stout....same thing. Most of the other brews I have made with Darkness were kegged....so obviously no issues there.

My first thought was sanitation, but I'm always mindful of that, and with no off flavors and the fact that it doesn't happen with other yeast (like the Barleywine I did last year or the stupid pumpkin spice beer I did because someone asked me to...and never drank it. Both with US-05), I have all but ruled out sanitation. I've been brewing and bottling for years, and have always had perfectly carbed beers. Just in case there are questions, I use a bottling bucket and prime accordingly. Storage temp is always consistent. Fermentation is temp controlled and within the yeast's recommended range. Literally everything is the same except for this yeast.

For heavier beers, I normally let it ride for about three weeks before bottling. It seems to be attenuating as expected (right on the money for the Scottish Ale and porters, slightly less for the stouts) but I am wondering if maybe it's lagging at some point and then coming back to finish consuming additional sugars while bottle conditioning.

Anyone ever experience this with Darkness?

 

[3 Dawg Night]

Might be a good split-batch experiment. Ferment half with Imperial Darkness and half with a similar yeast. See if the final beers are different in carbonation.

 

[Dgallo]

Fresh packs every time?

 

[monkeymath]

I've never used Darkness, but I did face the same problem with WLP002.
I then discovered that I like WY1469 better anyways, so I've never bothered to investigate or solve the issue.

 

[TestTickle]

Fresh packs every time?

I overbuild starters with all of my liquid yeast and save some for the next starter. I usually do about a handful of starters before starting over with a new pack. I'd have to look, but I believe the latest pack purchased in October and I was planning on adding some to my next order anyway. The Russian Imperial Stout was brewed with a starter from a previous pack. I considered the possibility of some contamination in my starters, but it's just odd that after years of doing starters this way that this is the only issue I have ever had with over-carbonation (ok, there was one long ago...but different yeast and chalked up to rookie carelessness). Plus, I would expect at least some off flavors, but the beers are delicious.

As for the carbonation, I opened one of the Scottish ales Thursday night, and I would estimate the carb level being around 2.8-ish to maybe 3. Not undrinkable by any means (I know a few homebrewers who carb higher and enjoy it), but as a guy who likes most beers in the 2.3 to 2.4 range, it's just a bit too much fizz for me to enjoy it the way I normally do. From talking with others who have experienced infected brews, I would have expected some gushers if that were the case, but I can't say that I have ever experienced infections before so perhaps I'm wrong.

I'm also still testing some of the milk stout that was overcarbed. I had some bottles that were chilled after about a month in the bottle, and they were perfect. I restocked with a few more after another month or two and those were overbarbed. I added a few more when I posted my OP, but think I may have mixed them up with the original ones I chilled because I have had two that were perfect. So in this case, if I did only have a few that were overcarbed, I can at least narrow it down to either insufficiently mixed priming solution into the beer when bottling (unlikely....again years of bottling and this has never been an issue) or a bug that was picked up with just those bottles...that all just happened to be together in the fridge? I don't know man, I might just be losing my mind.

I gifted a six pack of the overcarbed Russian Imperial Stout to a friend several months ago before I realized that there was an issue and he thought it was the greatest stout ever, so to each their own I suppose.

I've never used Darkness, but I did face the same problem with WLP002.
I then discovered that I like WY1469 better anyways, so I've never bothered to investigate or solve the issue.

Funny, I used to use S-04 and then WLP002 for all of my stouts and never had this particular issue. I did have issues with underattenuation (especially with S-04) which is why I switched to Darkness.

I'll just start with a fresh pack and go from there. Maybe in my old(er) age, I'm just getting too overconfident and careless with my processes and need to take a step back to the days when I showered and bathed in Star San before I touched anything. It's just weird that it seems to be this one particular yeast. I have about 8 different slurries on hand, although I keg most of the brews made with them, but never a problem with my bottled Hefe's, Belgians, barleywines, etc.

 

[Dgallo]

it's just odd that after years of doing starters this way that this is the only issue I have ever had with over-carbonation (ok, there was one long ago...but different yeast and chalked up to rookie carelessness). Plus, I would expect at least some off flavors, but the beers are delicious.

Is it possible that it “infected” with a brewers yeast that is positive for the STA-1 gene? Something like a saison yeast or sacc trios strain from a previous batch you brewed. This could cause the over attenuation but would explain no off flavors being present. It would also explain why it was all beers using darkness as they have all been brewed from the same over built starter.

Since it’s the same yeast strain from the same original overbuilt starter, it definitely leads me to believe it has something to do with the yeast itself

 

[TestTickle]

Is it possible that it “infected” with a brewers yeast that is positive for the STA-1 gene? Something like a saison yeast or sacc trios strain from a previous batch you brewed. This could cause the over attenuation but would explain no off flavors being present. It would also explain why it was all beers using darkness as they have all been brewed from the same over built starter.

Since it’s the same yeast strain from the same original overbuilt starter, it definitely leads me to believe it has something to do with the yeast itself

The head scratching is actually because it has happened with two different overbuilt starters (that info was buried in the first paragraph of my long winded post). I suppose there’s the possibility of both of the starters picked up some contaminant, and I’d be more likely to believe that if this happened with any of the other hundreds of starters I’ve done with other yeast. I use any of four fermenters, all stainless except one plastic that I rarely use anymore. Regardless, that’s kind of what I am going with…starting with a new pack and going back to my overly anal sanitation practices. I also recently bottled another batch of RIS and am brewing a smoked porter today with the same starter, so that could provide me with more info depending on how it turns out.

 

[Dgallo]

The head scratching is actually because it has happened with two different overbuilt starters (that info was buried in the first paragraph of my long winded post). I suppose there’s the possibility of both of the starters picked up some contaminant, and I’d be more likely to believe that if this happened with any of the other hundreds of starters I’ve done with other yeast. I use any of four fermenters, all stainless except one plastic that I rarely use anymore. Regardless, that’s kind of what I am going with…starting with a new pack and going back to my overly anal sanitation practices. I also recently bottled another batch of RIS and am brewing a smoked porter today with the same starter, so that could provide me with more info depending on how it turns out.

Is the stout the only beer you’ve bottled conditioned in that time frame? If you already mentioned this in a previous post.

 

[TestTickle]

Is the stout the only beer you’ve bottled conditioned in that time frame? If you already mentioned this in a previous post.

No. I may have been all over the place here.

RIS - Brewed mid to late 2021 with yeast starter from pack #1.
Scottish ale - brewed mid to late 2021 with yeast from pack #1
Milk stout - brewed late 2021 with yeast starter from new pack (#2)
Smoked porter - brewed late 2021 with starter from pack #2

All but the porter were overcarbed, but it was a smaller batch and didn’t last as long. We may have drank it before the issue became apparent (or maybe there was no issue?)