Scaling up a stout to an imperial stout

Beer Recipes
1

While I’m not a huge fan of imperial stouts I’d like to give one a try. I thought it might be fun to scale up the oatmeal stout recipe from Brewing Classic Styles and take a few liberties with it. What I’m not sure about is scaling specialty grains. If I double the grain bill do I really want to double all of the dark grains? I think with this I will take Gordon Strong’s advice and cold steep the dark grains in an attempt to reduce harshness from them.

Here’s what I’ve got so far:
BeerSmith 2 Recipe Printout - http://www.beersmith.com
Recipe: Argument From Authority
Brewer: Steve
Asst Brewer:
Style: Imperial Stout
TYPE: All Grain
Taste: (30.0)

Recipe Specifications

Boil Size: 8.00 gal
Post Boil Volume: 6.50 gal
Batch Size (fermenter): 5.50 gal 
Bottling Volume: 5.10 gal
Estimated OG: 1.106 SG (1.091 if 60% efficient)
Estimated FG: 1.029 SG  1.025 SG  (1.022 if 60% efficent)
Estimated Color: 54.9 SRM
Estimated IBU: 74.3 IBUs
Brewhouse Efficiency: 70.00 %
Est Mash Efficiency: 79.5 %
Boil Time: 90 Minutes

Ingredients:

Amt                  Name                                    Type          #        %/IBU       
16 lbs                Pale Malt, Maris Otter (3.0 SRM)        Grain        1        69.6 %       
2 lbs                Oats, Flaked, Toasted (1.0 SRM)          Grain        2        8.7 %       
1 lbs 8.0 oz          Victory Malt (or biscuit) (Briess) (28.0 Grain        4        6.5 %       
1 lbs                Caramel/Crystal Malt - 80L (80.0 SRM)    Grain        6        4.3 %

Cold Steep and add at 10 minutes:
1 lbs 8.0 oz          Chocolate Malt (350.0 SRM)              Grain        3        6.5 %       
1 lbs                Black Barley (Stout) (500.0 SRM)        Grain        5        4.3 %

28.00 g              Northern Brewer [8.50 %] - First Wort 90 Hop          7        22.3 IBUs   
42.00 g              Magnum [12.10 %] - Boil 60.0 min        Hop          8        40.5 IBUs   
11.00 Items          Fermcap-S (Boil 60.0 mins)              Other        9        -           
28.00 g              Northern Brewer [8.50 %] - Boil 20.0 min Hop          10      11.5 IBUs   
1.00 tsp              Irish Moss (Boil 15.0 mins)              Fining        11      -           
5.50 tsp              Yeast Nutrient (Boil 15.0 mins)          Other        12      -           
2.0 pkg              Dry English Ale Yeast (White Labs #WLP007)    Yeast        13      -           
  *** use 2 vials in a 1.5L starter with stir plate, per Mr Malty calculator
2.00 oz              Oak Chips Soaked in Irish Whiskey (Secon Flavor        15      -

Mash Schedule: My Mash/Sparge
Total Grain Weight: 23 lbs

Name              Description                            Step Temperat Step Time   
Mash In          Add 7.37 gal of water at 167.7 F        154.0 F      90 min

Sparge: Batch sparge with 2 steps (Drain mash tun, , 3.49gal) of 168.0 F water
Notes:

Created with BeerSmith 2 - http://www.beersmith.com

2

I think the recipe sounds good.  In my experience with a beer that big my efficiency usually drops.  I usually calculate 60% efficiency with a beer that big.  Also, I’m assuming you will be making a starter.  Even 2 vials of yeast will not be enough for this beer.  Other than that I say “go for it”!

Cheers,
Brandon

3

With a beer this big you would be much better off brewing a regular gravity beer (1.050 or so) and harvesting the yeast for this batch.

The grain bill looks fine to me.

4

The 2 vials were for a starter according to Mr Malty.

-Sent from the future.

5

Followup question: with an FG of 1.029 is this going to be like syrup? The biggest problem I have with imperial stouts I’ve tried is they are too sweet for my taste. Should I use a more attenuative yeast like WLP007 (Dry English Ale)?

6

I prefer WLP007 in big beers like this, as well as my Irish Stout and Irish Red.  I like the recipe, btw.

7

I think 1.029 will taste sweet, but maybe not like syrup.

I have a quad fermenting right now with a similar OG to your recipe that stalled at about 1.025 and it was very sweet.  Too sweet, for me.  But I like my beers strong and dry.

My old ale also starts around the same OG and tends to finish around 1.015.  Definitely not overly sweet at that FG.

The alcohol should offset some of the sweetness, but I’d go for something a bit more attenuative.

8

If you want a drier version of a RIS, you can go lower but I wouldn’t shoot for below 1.025 or so. It needs that residual sweetness or it feels thin and bland (my biggest problem when brewing RIS is actually over-attenuation).

1 lb of black barley is a LOT. Investigate dehusked to reduce astringency, especially since you’re shooting to dry it out a bit more than usual. Replacing 75% of the dark roasted grains will reduce astringency but give you just enough bite to balance out the sweetness (along w/ the hops and alcohol). The hop bitterness will fade, the astringency wont.

9

Thanks everyone for the input.  I’ve edited my original post and changed the yeast to WLP007.

Looks like WLP007 will bring it down to 1.025 (assuming my efficiency doesn’t drop, I looked at 60% and it’s still quite a big beer with no additional grain or adjuncts).

As for the astringency I’m going to cold steep the dark grains and add them late in the boil. This should, according to Gordon Strong, reduce the astringency.

Also, I’m not going to soak the oak in whiskey. I will add the oak then, per Denny’s article last month, I’ll get the right amount of whiskey to add prior to bottling by adding some to samples then scaling up.

I re-listened to the Jamil show on imperial stouts and the one on oak aging today and I think I’m on the right track. The only thing I won’t be doing that was suggested is repitching from a previous beer. I’ll just have to create a decent starter and aerate the heck out of it.

10

I wouldn’t be surprised if WLP007 takes you below 1.025.  I routinely get 78-80% attenuation with this yeast, no matter the size of the beer.

11

You could also add some sugar or candy syrup to get your FG down a bit.

12

I would mash cooler personally.  Anytime I’m making a BIG beer like this, and I’m pushing the limits of attenuation, I go for 149 F, and let the yeast go as far as they will. There will still be plenty of body left with 75%+ attenuation from 1.100.

13

I’m at work right now but when I get home I’ll work in these suggestions.

-Sent from the future.

14

So, according to Beersmith if I lower the mash temp to 150F then my FG should be 1.020 (1.017 @ 60% efficiency).

I think I’ll try that and if I miss my pre-boil gravity then I’ll add sugar to bring it up.

15

I would add DME as opposed to sugar if I miss my efficiency/OG, but that is just me. But, in a beer that big it may not matter.

16

Well my concern is more getting the FG down and not having it too syrupy.  That’s why I was thinking of using sugar. Or would it matter?

-Sent from the future.

17

Man this brew day sucked. How does 53% efficiency sound? Ran out of DME on the 2nd runnings and used sugar. So the stout OG was only 1.081 and the brown ale (second runnings) was 1.040.  Oh well, it will make beer. Never doing parti-gyle again, though…or maybe I’ll torture myself every father’s day until I get this right! Hmm…nah!