Mash Temp Advice - Big 1135 Imperial Stout

I’m planning on brewing a big Imperial Stout this Saturday. Recipe is below. I know there are a lot of specialty malts, but I was going for a Firestone Walker Parabola’ish beer, (minus the bourbon barrel aging) so I wanted to use all the malts that are listed on the FW/Parabola website description.

That being said, it’s going to be a huge beer, 1.135 OG. I’m looking for a chewy/lots of mouth feel beer to sip in the dead of Winter. Parabola, Speedway Stout, Big Black Voodoo Daddy, Big John, style.

I’m planning on doing a single infusion mash with batch sparge. I was originally thinking 153 mash temp for 90 minutes and then sparge with 190 degree strike water. However, will I have enough fermentable sugars at that high a sparge temp for such a huge beer? Definitely want to give the yeast some help.

Any input is appreciated.

Fermentables
Fermentable Amount Use PPG
Maris Otter Pale (UK) 20.0 lb 53 % Mash 38
Munich Dark (DE)
4.0 lb 10 % Mash 35
Chocolate (UK)
2.0 lb 5 % Mash 31
Flaked Oats
2.0 lb 5 % 37
Golden Naked Oats (UK) 2.0 lb 5 % 33
Crisp Roasted Barley 2.0 lb 5 % 34
Caramel/Crystal 40L (US) 1.25 lb 3 % Mash 34
Caramel/Crystal 120L (US)
1.25 lb 3 % Mash 32
CaraHell (DE)
1.0 lb 2 % Mash 35
Carafa III 1.0 lb 2 % 34
Black Malt (US)
1.0 lb 2 % Mash 32
Hops
Hop Amount Time Use Form AA
Columbus (US)
3.5 oz 60 min Boil Pellet 15.0%
Hallertau (DE)
1.0 oz 10 min Boil Pellet 4.5%
Hallertau (DE)
2.0 oz 1 min Boil Pellet 4.5%
Yeasts
Name Lab/Product Attenuation
Dry English Ale Yeast
White Labs WLP007 73.0%
Predicted Stats
Batch Size
6.5 gal
Boil Time
90 min
Efficiency
65.0%
1.135 OG 1.037 FG 75 IBU 12.9% ABV 103 SRM 0.56 IBU/OG

153 is pretty much right in the middle of the beta/alpha amalyse enzyme activation range, where you are going to have a not too dry, not too wet beer.

"Chewy" mouthfeel is obtained through a combination of both high mash temps and protein-rich malts. I would mash closer to 155, and you have enough of the protein-rich malts in your current grain bill to thicken up the mouthfeel.

190 is too high for sparge water. The science behind sparge temp is you want to have a high enough temp to stop enzymatic activity, which starts at about 168. However, tooo high of sparge temps combined with low PH will start to release tannins from the grain husks. This starts at about 190F with PH under about 5.0. Your mash PH will be lower than average just due to the high % of darker malts, which are lower in base PH.

All that to say, you shouldn't sparge at 190F. It should be closer to 168-175.

Good luck!

IMO, large grainbills are better suited to lower mash temps since they already contain more of the unfermentables than do smaller grainbills. HUGE grainbills are the extreme side of that. You are dealing with a HUGE grainbill with 3.5 lbs of crystal and 6 lbs of roasted grains; there will be a lot of unfermentables regardless of how you mash this. Not to mention you need to give the yeast plenty of easy-eating sugars otherwise it'll crap out when the sugars start getting more complex and the ABV starts getting stressful. My opinion is no higher than 150F, possibly closer to 148F would be a good mash temp for a beer of this caliber. I might even step it up to 156-158 after 45-60 minutes at the lower temp since I have been finding it helps contribute to the fermentability of the brew while retaining some of those residual sweet notes.

HTH!

Welp, those are two quite contrasting responses.....

Guess I'll wait for more thoughts on this.

As far as the 190 Sparge temp, I've looked into this quite a bit and a lot of people have discussed weather the strike water should be 170 or the sparge temp grain bed should be 170. I found a good discussion of this in the link below. If I'm dumping 3 gallons of 190 degree water into a 150 degree grain bed it'll level at at 170, no?

https://www.homebrewtalk.com/f36/batch-sparge-strike-temperature-100793/

IMO and what I would do myself is a 150 step for 60 min, 156 for 15 min, mash out for 15.
Grain bill has a lot of crystal type grain, mash too high and you will be drinking soda style beer.
My 2 cents !

AngryMonk said:

IMO and what I would do myself is a 150 step for 60 min, 156 for 15 min, mash out for 15.
Grain bill has a lot of crystal type grain, mash too high and you will be drinking soda style beer.
My 2 cents !

Click to expand...

Is there a calculator that will tell me the volume and temperature of water to bring the 2nd step up to 156? What temperature should I mash out at?

+1 to stpug. You need enough base malt (lintner 120+) to convert all those dark grains. Not sure 53% base malt and 47% low-to-no fermentable malts will get you there, especially at high mash temps. If you can get your base malt up to 60-65% and mash at 152 or lower you'll still have mouthfeel with better fermentability. Even so, you will need a massive starter of some high attenuation yeast. You may even need to throw some wlp099 or champagne yeast at it after a couple of weeks of fermentation.

Oh, and there are a number of good infusion calculators out there. There is a good one built into BeerSmith.

As one brewer mentioned, 153F is the happy medium temp for enzymes. Mash pH has to be in the happy medium, too.. Here's the thing, will conversion at 153F produce the style of beer being brewed?
Some things to consider. Beta thermally denatures quickly at 153F. When beta denatures, alpha continues to work. Alpha produces non-fermentable sugar. Mashing at 155F will thermally denature beta faster than at 153F. Alpha will be active longer.
Mash pH has an affect on enzymatic action, a few points outside optimum, enzymes stall.

Though crystal will help form foam and head, too much has an adverse affect on the same. Its a thing called lipoxygenase, and fatty acids.

Tannins aren't stripped at high temp and low pH. If that happened, decoction mash wouldn't be boiled. Mash can be boiled without releasing tannin if pH is below 5.8, better at 5.5. Brewers that fly sparge cease sparging once mash pH reaches 5.8.

Depending on what a brewer calls high temp mashing. High temp mashing produces wort that won't have what it takes for yeast to reproduce. Fermentation is shortened. The final product will be low alcohol. It's part of a method that can be used to make non/low alcohol beer.

Marris might be hard pressed to convert dark munich, maybe there's enough marris to do it. Refer to the malt spec sheet to see what the diastatic power is. If it isn't on the spec sheet, e-mail the producer and ask for it. Add the recipe and mash schedule in the e-mail and see what they think, before you brew it. Or, just go for it and see what happens.