Stuck imperial stout

[thegrantickle]

Hi squad

I have an imperial stout which has stuck in fermentation.

OG - 1.145 15/11
SG - 1.1 21/11
SG - 1.094 26/11
SG - 1.094 05/12

It is roughly a 20L batch. However I have a bit of a plan which might work but wanted to run it by folk.

- this is the first 20L of what will be a double batch run of total 40L
- i brewed 20L at a time cause that’s what my maximum boil kettle capacity is
- the stout is to be racked onto coconut/cacao nibs/vanilla beans/tonka beans in a secondary bucket which is 60L volume
- the original plan was to brew another 20L and then rack this on top of the first batch once it had finished fermenting in primary

- if I rack the first batch onto the coconut etc now
- brew the second batch
- ensure the second batch has plenty oxygen (I think this might have been issue
- rack it on top of the first (stuck) batch
- the lively second batch should restart fermentation from sugar left in the other batch till they’re both fermented out

Anything wrong with this plan/ that I’m missing?

 

[Caramel Ox]

My advice would be to resolve your batch 1 issues before you do anything on batch 2. How much yeast did you pitch? What temperature is the beer at?

 

[thegrantickle]

I pitched 2 packs of WHC Bond (22g total). Started it off at 16C and no pressure, brought it up to 20C and fermented under about 10psi after about 4-5 days.

It’s in a stable temp controlled fermentation fridge.

 

[Caramel Ox]

Ok the Brewfather pitching rate calculator suggests 5 packets for that OG.

Is there a lot of sugar in it or is it all malt?

 

[thegrantickle]

Ok the Brewfather pitching rate calculator suggests 5 packets for that OG.

Is there a lot of sugar in it or is it all malt?

Bloody hell. There is 1kg sugar in it. There is also 1.5kg lactose in it. So was expecting to finish around 1.056.

I have another 2 packs sitting there I was planning to use for the second batch. Could get a starter going with some DME, get it lively and pitch that in? Thoughts?

 

[Sadfield]

In the second batch, I would suggest adding the sugar after primary fermentation. And then the lactose just before packaging.

FG of 1.056? Sorry, I've no advice for the resulting diabetes.

 

[thegrantickle]

In the second batch, I would suggest adding the sugar after primary fermentation. And then the lactose just before packaging.

FG of 1.056? Sorry, I've no advice for the resulting diabetes.

Not bad ideas. Noted.

1.056 smashed full of lactose tho.

 

[Caramel Ox]

If you can make a starter then you can use just 1 packet more. Take off the fermenter pressure and you may be able to get it going again.

You could rework the second batch recipe to compensate for a higher FG on batch 1, so it is closer to the intended when combined?

 

[foxy]

Hi squad

I have an imperial stout which has stuck in fermentation.

OG - 1.145 15/11
SG - 1.1 21/11
SG - 1.094 26/11
SG - 1.094 05/12

It is roughly a 20L batch. However I have a bit of a plan which might work but wanted to run it by folk.

- this is the first 20L of what will be a double batch run of total 40L
- i brewed 20L at a time cause that’s what my maximum boil kettle capacity is
- the stout is to be racked onto coconut/cacao nibs/vanilla beans/tonka beans in a secondary bucket which is 60L volume
- the original plan was to brew another 20L and then rack this on top of the first batch once it had finished fermenting in primary

- if I rack the first batch onto the coconut etc now
- brew the second batch
- ensure the second batch has plenty oxygen (I think this might have been issue
- rack it on top of the first (stuck) batch
- the lively second batch should restart fermentation from sugar left in the other batch till they’re both fermented out

Anything wrong with this plan/ that I’m missing?

I reckon with all that lactose, and that is a lot for 20 litres you are done. What was the grain bill?

 

[Sadfield]

No where near done.

Lactose will add 340 gravity points per kg per liter, so c26 gravity points in 20L.

94-26=68. 1.068 from a starting 1.119 if you take lactose out of the equation. Currently at 40% attenuation from a yeast more than capable of fermenting an Imperial Stout.

 

[foxy]

No where near done.

Lactose will add 340 gravity points per kg per liter, so c26 gravity points in 20L.

94-26=68. 1.068 from a starting 1.119 if you take lactose out of the equation.

It depends on his grain bill. He will have other non-fermentable grains in the bill, and if he is as heavy-handed, as with the lactose, he could well end up finishing high.

 

[thegrantickle]

Grain bill:

It is a big, sweet, thick beer. I have brewed it before, but with a different yeast. It is a recipe based on one from a commercial brewery.

 

[Northern_Brewer]

In the second batch, I would suggest adding the sugar after primary fermentation. And then the lactose just before packaging.

100% to these suggestions (well, I'd add the sugar towards the end of primary fermentation, not after it's completely done, add it whilst the yeast is still in its groove rather than starved and shut down) - even without the added sugars any yeast is going to struggle with the osmotic pressure from the wort sugars. High sugar concentrations are almost as stressful to yeast as high alcohol concentrations, so you want to minimise the amount of sugar they see at any one time (and eg a mix of 5% alcohol and 1.070 sugar is less stressful than 10% alcohol or 1.120 sugar on their own)

And personally I'm not a big fan of lactose. Given that you're struggling for attenuation, I'd be tempted to just skip the lactose in part II now that you're fighting to rescue the batch, it seems a bit pointless to struggle to attenuate and then undo the hard work by dumping lactose in it.

fermented under about 10psi after about 4-5 days.

Not sure what you're trying to achieve with pressure fermentation here, other than making double-sure that the yeast doesn't get enough oxygen?

But yeah, oxygen is always good in these cases. This is a useful primer for high-gravity happiness :

https://quaff.org/wp-content/uploads/2012/11/HighGravityFermentation-1.ppt

A useful group of yeasts for this kind of beer is the alleged-Rochefort family, dregs from Rochefort beers (most complex), WLP540, BE-256 etc - they're British yeasts from the Whitbread family (so related to Bond) but adapted to higher ABVs.

But yeah, broadly your least worst option at this stage is to mix Part II wort with the part-fermented beer from Part I, add extra yeast and do everything you can to make the yeast happy, and hope...

 

[Sadfield]

I did wonder if getting the second part underway and top cropping back into the first would be a good idea.

 

[peterpiper]

1.145 OG so you're maybe aiming for 17% ABV.

With very high OG, you need to oxygenate a lot, and hit it with a lot of healthy yeast. Aiming for 15-20 million cells per ml.

For the 1.125 ( equivalent total) OG, Award stout I did early this year:

1) prepare a 1 gallon starter, made with DME (OG 1040) 2 days earlier. I used Nottingham yeast. Chill in fridge the night before brewday. On brewday pour off liquid, and use yeast slurry for the brew. For enough yeast cells for 20L at that OG, you want 300-460ml of yeast slurry (assuming slurry contains typical 40% solids).

2) Use a sterile fish tank bubbler for first 12hours (unless you can blast from an oxygen cylinder).

3) Krausen is likely to be over double the batch volume! So max 10L in a 25L bin. I'd not realised this, so ended up splitting batch, and mopping floor at 4am.

4) Start adding suger additions, once fermentation slows down, 200g at a time, maybe every day or two.

Don't use leftover yeast for a subsequent batch. It will be a stressed yeast,that probably won't cope. The lowish OG starter, gives a healthy, un-stressed yeast.

I racked off, then let the Award stout settle for around 10 days before botteling & kegging. Then realised I should have kept back some of the alcohol tolerant yeast, for bottle priming.
Ended up, using CBC1 bottling yeast, which worked fine.

Left to mature, on whisky barrel oak staves (off Amnzn). Cut to 1cm strips, to increase surface area, and so one or two strips could go in each bottle. These were steeped in cheap (Lidl) whisky, for a few weeks, to rejuvinate before use.
Plan to start on keg this Christmas. Bottles are wax sealed, so hopefully can mature for a few more years, but some will be going as gifts this year.

 

[foxy]

Grain bill:

View attachment 106510

It is a big, sweet, thick beer. I have brewed it before, but with a different yeast. It is a recipe based on one from a commercial brewery.

So, 13.5 kg of grain mashed in a 20-litre pot wouldn't work. How did you mash your grains?

 

[thegrantickle]

So… I made a stepped up starter from my remaining 2 packets of dry yeast. 2L @ 1.036 then 2L @1.050 and got a decent amount of yeast slurry. Pitched it this morning and it has restarted fermentation pretty vigorously - happy days. Hopefully it will finish out without issue now.

 

[foxy]

So… I made a stepped up starter from my remaining 2 packets of dry yeast. 2L @ 1.036 then 2L @1.050 and got a decent amount of yeast slurry. Pitched it this morning and it has restarted fermentation pretty vigorously - happy days. Hopefully it will finish out without issue now.

Why make a starter with dry yeast? Just pitch the number of packets needed. Dr Chris White suggests not to make a starter from dry yeast in the book Yeast. Making a starter from dry yeast depletes the cell reserves that are already in the dry yeast.
I am still curious to know how you mashed the grain?

 

[thegrantickle]

Just took a gravity reading - made it down to 1.088 so it is moving in the right direction. Still appears to be plenty of yeast in suspension doing its thing