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Imperial stout stuck fermentation?

Yeast & Fermentation
#1

So I’m 3 weeks past brew day for the NB Imperial Stout. The starting gravity reading on brew day was 1.076. Over the next few days, fermentation was quite vigorous, and thankfully I had a blowoff tube on my primary from the get go or I would have really had a mess on my hands (it was still pretty bad, and my blowoff tube is a lost cause I think). Didn’t have any inkling that there was a problem until after I racked to secondary and decided to take another gravity reading before plugging and storing. My reading was 1.030. Per the recipe it is supposed to sit for another 3 months yet in secondary before bottling.

So my question is, do I have a stuck fermentation here or will it finish off, slowly fermenting over the next 3 months. If it is stuck, what do I do about it? Just add more yeast to the secondary? Yeast starter, or could I just use a smack pack? This is my first go at a high ABV beer, so I’m in uncharted water here.

Thanks in advance.

#2

[quote=“gstock”]So I’m 3 weeks past brew day for the NB Imperial Stout. The starting gravity reading on brew day was 1.076. Over the next few days, fermentation was quite vigorous, and thankfully I had a blowoff tube on my primary from the get go or I would have really had a mess on my hands (it was still pretty bad, and my blowoff tube is a lost cause I think). Didn’t have any inkling that there was a problem until after I racked to secondary and decided to take another gravity reading before plugging and storing. My reading was 1.030. Per the recipe it is supposed to sit for another 3 months yet in secondary before bottling.

So my question is, do I have a stuck fermentation here or will it finish off, slowly fermenting over the next 3 months. If it is stuck, what do I do about it? Just add more yeast to the secondary? Yeast starter, or could I just use a smack pack? This is my first go at a high ABV beer, so I’m in uncharted water here.

Thanks in advance.[/quote]

Did the kit list a likely FG? Did you just take the one reading at 1.03? You would need at least two readings to know for sure if it has stalled.

#3

Extract, partial mash, or AG?

Is the 1.030 reading from a hydrometer or a refractometer?

#4

It’s an extract kit. I only took 1 reading with a hydrometer. I was hoping that someone else out there had a similar experience. I realize that higher alcohol beers run the risk of the yeast dying off, but I also wasn’t sure how long fermentation would take to complete…would it be (mostly) done in the typical couple of weeks and use the remaining time to smooth out, or would it literally take a few months to actually get down to a more standard FG. There was no FG listed with the recipe so I don’t know what to expect.

#5

It may not be “stuck”. It may just be “done”

1.030 seems a little high for even an extract batch. But it’s hard to tell with the dark extract and the specialty grains how unfermentable the wort is.

Keep the beer in a warmer area if you can to help the remaining yeast finish up the job.

#6

I have been storing at between 68-70 degrees, which should continue for the most part (may get slightly colder as we get into winter). If I were to pitch more yeast now, then let it sit for the recommended 3 months in secondary…what would be the pros and cons? Would I be in danger of having bottle bombs once I do eventually bottle? Would I need to be careful of autolysis and re-rack again (tertiary racking?) at some point? Or am I better off not messing around anymore and just living with what I have (1.030 FG and est. ABV of 6.04% instead of ~8% )?

#7

Oh don’t worry, there are plenty of people with this problem…

With some recent cold spells I thought temp might be an issue but that doesn’t seem to be the problem based on what you said. So I’ve got a couple more questions:

What yeast did you use and how much?
When did you rack it?

The liquid yeast packs are simply not enough yeast for a beer that size. And if you racked it early you may have just caused a halt to the fermentation.

Unfortunately there are a lot of mixed stories about restarting fermentation once it has stopped. Some successful. Some not so much. With that amount of booze already present it is tough to get going again. You could try a package of something like US-05 which I’ve heard works at times. If that doesn’t work I would just let it ride. Or if it’s too sweet you could make another stout and blend them. This would lower the ABV but improve the product if you don’t like it.

First things first though, make sure to take hydrometer readings before racking.
:cheers:

#8

I made an imp stout extract kit from a competitor last year and it finished at 1030 after 3 weeks. That kit came with a package of champagne yeast to use when bottling. I racked into a glass carboy and added the champagne yeast. I left it for about 9 months and it was at 1024. I then aged most of it with bourbon and oak but bottled a few regulars. Both came out great. A little sweet still, but a crowd pleaser 18 months later.
My guess was that I probably did not pitch enough yeast and I know that I didn’t properly oxygenate the wort (it was my 4th batch). I luckily didn’t get any strange flavors that I hear about from the champagne yeast.

#9

This is simply not a true statement. The yeast will multiply to a level that they need to be at for fermentation. 1 yeast cell will ferment a 5 gallon batch of 1.100 beer/mead/wine.

You can help them along by making a starter. Or let nature take it’s own course.

Will the beer be better with a starter? Only the consumer’s palate can make that decision.

#10

If you want your beer to taste good you should use proper pitchingrates. For an Ale that is about 750000 cells per ml per plato. Taking this into account a single vial or a packet of Dry yeast is nowhere near enough yeast for an optimal fermentation.

Sure sometimes it ferments out anyway but you will probably get off flavours due to yeast stress or it may just not finish. It all depends on how healthy the yeast is.

Edit: And if you want to restart fermentation a starter is the only way to go. Pitching Dry yeast into a stalled fermentation Most of the time does nothing.

http://otterbo.wordpress.com <-- Öl o hembryggning!
#11

[quote=“Nighthawk”][quote=“inhousebrew”]

The liquid yeast packs are simply not enough yeast for a beer that size. And if you racked it early you may have just caused a halt to the fermentation.
[/quote]

This is simply not a true statement. The yeast will multiply to a level that they need to be at for fermentation. 1 yeast cell will ferment a 5 gallon batch of 1.100 beer/mead/wine.

You can help them along by making a starter. Or let nature take it’s own course.

Will the beer be better with a starter? Only the consumer’s palate can make that decision.[/quote]

I probably should have tossed in an “IMO” for that statement or rephrased it because of course you are correct. But IMO after making a host of crappy high gravity extract brews that turned out terrible with one smack pack my palate is telling me one pack is simply not good enough to get the job done properly. Can’t tell you how many terrible bottles of big beer I slurped down before learning about yeast.

#12

Originally I used Wyeast 1728 Scottish Ale smack pack. Apparent attenuation: 69–73%. Flocculation: high. Optimum temp: 55°-70° F. I also made a yeast starter approximately 36 hours prior to adding it to the RIS wort. I am thinking that I am going to make another starter and add it to the secondary. Probably just using the same yeast strain, but if anyone has any recommendations, I’d take them at this point. Thoughts?

#13

[quote=“inhousebrew”][quote=“Nighthawk”][quote=“inhousebrew”]

The liquid yeast packs are simply not enough yeast for a beer that size. And if you racked it early you may have just caused a halt to the fermentation.
[/quote]

This is simply not a true statement. The yeast will multiply to a level that they need to be at for fermentation. 1 yeast cell will ferment a 5 gallon batch of 1.100 beer/mead/wine.

You can help them along by making a starter. Or let nature take it’s own course.

Will the beer be better with a starter? Only the consumer’s palate can make that decision.[/quote]

I probably should have tossed in an “IMO” for that statement or rephrased it because of course you are correct. But IMO after making a host of crappy high gravity extract brews that turned out terrible with one smack pack my palate is telling me one pack is simply not good enough to get the job done properly. Can’t tell you how many terrible bottles of big beer I slurped down before learning about yeast.[/quote]

This is a statement I can back. You have done your testing and found that there is a difference for you.

In a study done at BYO, they found their test to be inconclusive if there was a difference in FG and taste.

This may change with different yeast strains also.

#14

Extract kits often finish with very high gravity, especially when using dark extract, which typically contains a lot of crystal malt as part of the manufacturing process.

I would add at least a half pound of cane sugar to jack up the alcohol, and to perhaps lower the final gravity a little as well (after the added sugar ferments).

I also like the idea of adding a pack of champagne yeast. If you add more Scottish yeast, even with a big starter, it won’t help at all. This yeast does not attenuate very well so it would be a wasted effort. But champagne yeast is cheap. It couldn’t hurt, and it might help quite a bit.

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