Russian Imperial Stout attentuation issue

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SteBeardface

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Hi guys,

I recently brewed the Brew Your Own Old Rasputin clone (link) with reasonable success from start to finish, just ended up diluting it a little as I over sparged by a few litres and didn't boil off some before adding the hops.

That aside... I pitched a nice big starter of White Labs Dusseldorf Alt Ale to the 22L of wort, SG - 1.076. After a couple weeks, the gravity was 1.026. I warmed it 20 °C, but this hasn't changed the gravity over the last few days. I gave it a stir last night to suspend the yeast, but I'm pretty sure it has stopped/stuck. Attentuation is roughly 66%, I believe, which is within range for the yeast, but I was expecting an FG closer to 1.018 (supposed to be 1.022, but it is more dilute than the recipe shows.)

Question is, would it be possible to push this any further at all? I was thinking about pitching a packet of US-05 last night, but I'm not sure how it would cope in an already fairly alcoholic environment with no oxygen to feed off, let alone the question of whether it actually help.

As usual, your help is greatly appreciated!
 
I would expect US05 would shift it downwards OK. If you have saved any from skimming or trub for re-use, that might help the issue of alcohol tolerance. Otherwise doing a 1L starter using DME (~ 100g?) with the dry yeast and pitching the whole lot after 2-3 days might also work well.
 
Attenuation will depend on yeast strain, grainbill, mash temperature and mash length. There's quite a bit of crystal and roasted malts in that recipe so I'd expect it to finish a bit high, but then there's also a fair amount of sugar too..which might average that out :) If you mashed high then it might well have finished.

If you are worried about the effect of alcohol on rehyrdrating the yeast then just rehydrate it in warm water as they instruct, then add some of your beer to it in a couple of steps to get it to the same temperature of your beer then chuck it in. USo5 has very low O2 requirements and dry yeast doesn't need it anyway, assuming you pitch enough. I think re-oxygenating your beer at this point would be a bad idea.
 
That's a strange yeast choice for an imperial stout, the attenuation range from White Labs is 65 - 72%, whereas the recipe you linked shows 79% attenuation. I reckon US05 will push it down a bit even if you just chucked it straight in.
 
Rarely have I seen advice to pitch a second yeast into a situation like this ever do anything significant. Unless that is the second pitch is some kind of wild strain. I think nutrients are needed to help the new strain establish itself.
 
foxbat said:
Rarely have I seen advice to pitch a second yeast into a situation like this ever do anything significant. Unless that is the second pitch is some kind of wild strain. I think nutrients are needed to help the new strain establish itself.
Click to expand...
Think it was Experimental Brewing who discussed this, for the new strain to take hold you would need to pitch a massive amount of yeast as there's not much left for it to grown from so you'd be best matching the "cell count" for that stage of fermentation which would be 4 - 5 times a standard pitch. Don't think there's much evidence to support it but makes sense.

I just ran a 1.076 OG, 68c mash and WLP 036 Alt through a calculator and the predicted FG is 1.025 so spot on for what you've got. The recipe suggests Engish ESB strains which are more attenuative and would have got you down further. How's it taste? I don't know if trying to get it down further is worth the hassle as it's really hard to do.

Edit: Just noticed I was reading the wrong recipe, interesting that WY 1007 and WLP 036 are meant to be the same strain, Wyeast list a much higher attenuation of 73 - 77% and the author of that article tends to use Wyeast yeast based on his other article series.
 
Last edited:
68 degree mash would definitely contribute.
4wiw, I kegged an imperial stout last week that went from 1.095 to 1.015 fermented with us05.
 
Loads of replies! Thanks guys! :)

By the sound of it, the yeast of choice wasn't the best. In all honesty, I picked it over the Wyeast for a change as I had not used White Labs stuff before, so maybe this wasn't the best idea in the end.

I haven't tasted it yet, but the smell is amazing! I think I might just leave it and get it bottled. It's coming out at 6.6% ish, which is not an imperial stout in the slightest, but it's as everyone keeps saying - if it's nice, who cares!

I wouldn't mind trying this again in the future, though I might just go straight in for US-05 for the sake of ease. Got a few other brews to get done beforehand, all recipes with dried yeast, so I don't foresee issues with these (touch wood...)
 
As others have said, it's pretty hard to rescue a brew once the yeast has chewed all the simple sugars - wine yeasts can help if the original yeast has died before eating all the simple sugars, but not if the simple sugars have already gone. And even beer yeasts need a bit of simple sugar to help them get going. You could start messing about with Brett etc but if you enjoy it as it is then I would just leave it, perhaps use some for blending/ageing.

WLP540 is a useful yeast for beers like RIS as it's a British yeast (so has more character than eg US-05) but has adapted to higher ABVs, allegedly at Rochefort.

RIS is another "style" that's based on just one original beer, the Barclay/Courage one, Ron Pattinson has written quite a bit about it (including recipes) at eg
http://barclayperkins.blogspot.com/search/label/Russian Stout
http://barclayperkins.blogspot.com/search/label/Imperial Stout

There's tips on high-gravity fermentation here.
 
Zephyr259 said:
Think it was Experimental Brewing who discussed this, for the new strain to take hold you would need to pitch a massive amount of yeast as there's not much left for it to grown from so you'd be best matching the "cell count" for that stage of fermentation which would be 4 - 5 times a standard pitch. Don't think there's much evidence to support it but makes sense.
Click to expand...

I used Danstar English Ale yeast for a Sarah Hughes Ruby Mild (this was at the end of 2016, when it first became available). After 0nly 3 days it had stuck at 1.020. I added US05 to get it down to 1.010, but it was not a dry sachet, but a 250ml bottle of re-used trub that got chucked in, without much ceremony. That sort of adds weight to the "cell count" theory on adding a second yeast after the first one has more or less done.
 
From what I can gather, I reckon it was the choice of yeast that was wrong, which is my fault for not putting in the research. The starter may not have been the best either as the yeast packet was actually quite old (Apr 2019, 8 months past packaging date when pitched to starter).

I have decided to shove the stout in a pressure barrel and I'll prime with brown sugar for that extra flavour and forget about it for a good few months. At least if it decides to push on at all, there won't be any bottle bombs!

I think I'll give it another go at some point, use the Wyeast suggestion and be sure to use it as fresh as it can be. Until then, I think I'll get my Jaipur clone on the go...
 

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