Mash and fermentation temps for a RIS

Kershner_Ale · 01-29-2012, 06:19 AM

Wondering if folks can help me out. I've been researching various recipes for a russian imperial stout and it appears the mash temps and fermentation temps I'm finding are all over the board. I want to brew a RIS that has lots of residual malty sweetness so I was planning on mashing in the 155 F range. I've also read you want some diacetyl in a RIS to help balance with the other flavors, so I was thinking of fermenting on the warm side (68 F or so). Am I off on my thinking here? I noticed the Tricentennial Stout recipe in Brewing Classic Styles suggests a 149 F mash temp for 90 min and a fermentation temp of 70 F for Irish Ale yeast. But this same recipe lists FG at 1.037. How do they get such a high FG with a long mash temp? I realize Irish Ale does not attenuate like US-05 or similar yeasts but doesn't 1.037 seem especially high? Jamil's Czar's Revenge recipe calls for a 154 F mash temp and a 67 F ferm temp with a high attenuating yeast (California Ale, US-05) but still lists FG at 1.030. What other variables am I missing that contribute to a good malty residual sweetness?

**smokinghole** · 01-29-2012, 11:36 AM

http://www.brewersassociation.org/pages/publications/the-new-brewer/online-extras/show?title=style-spotlight-imperial-russian-stout

Check that out.

You're missing the fact that these typically have a long boil. So when you boil down 10 gal of wort all the complex sugars that are nonfermentable by yeast are being concentrated in your wort. Say you started at a preboil gravity of 1.070 and ended up at 1.140. This is theoretical mind you not factual numbers. Say the 1.070 would have fermented down to 1.015 for you. Then the 1.140 will ferment down to approximately 1.030. You have all the same sugars in the same beer but the volume is half so it will basically double the residual sugars that remain. I don't know what you're recipe is like, but I advise to keep your specialty grains to less than 25% of the recipe. Its been my experience that once you go much past the 25% you start running into abnormally nigh FGs even with lowish mash temps. I mashed my last clean RIS at 149 and it ended up at 1.032. My most recent iteration I mashed at 158 because I was giving it the Wyeast 9097 Old Ale blend. At transfer to secondary that gave me a 1.046.

**theonetrueruss** · 01-29-2012, 01:28 PM

Just a thought, but the high FG may also have to do with the alcohol tolerance of the yeast. Once you hit 10%abv a lot of beer yeast start to give out. It really depends on the yeast though.

**smokinghole** · 01-29-2012, 01:43 PM

That's very true. My scenario is based on using yeast that can go to 15% though.

**BrewKnurd** · 01-29-2012, 01:55 PM

smokinghole: agreed that many recipes have a long boil, but neither of the recipes listed by the OP do, so that's not what he's missing in this case.

Kershner: Darker malts generally lead to less fermentable wort. And obviously RIS uses lots and lots of dark malt.

www.scientificsocieties.org/jib/papers/2005/G-2005-0330-275.pdf

**smokinghole** · 01-29-2012, 02:33 PM

Exactly. I guess I was alluding to that with out saying it. When you use as much dark malt as used in high gravity stouts then boil the volume down to hit a high gravity you're increasing their effect. I don't know those recipes so I don't know if they have a 60 min or 120 min boil. I boil the hell out of my recipes to get decent efficiency.

**barryshomebrew** · 01-29-2012, 05:28 PM

Haha, I thought this was awesome.

"The beer was generally matured in oak vats. It is said that Russian Stout for the domestic market was taken out of bond and rolled around the yard each month to "simulate the effect of the treatment it would have received in transit to the Baltic."

"Honey, I'm going out to walk the beer. Cya later!"

Kershner_Ale · 01-29-2012, 05:44 PM

Thanks guys, that helps clarify things. I planned on a 90 minute boil and using Wyeast 1728 Scottish Ale yeast.

The recipe I'm using is Midnight Sun Brewing Company's Berserker Stout recipe (10 gallon version):
7.00 lbs. Alexander LME - Pale
24.50 lbs. Pale Malt(2-row)
2.00 lbs. Special B Malt
1.50 lbs. Chocolate Malt50
1.00 lbs. Black Patent Malt
1.00 lbs. Flaked Barley
0.75 lbs. Munich Malt(2-row)
0.50 lbs. TF Torrefied Wheat
1.00 Lbs brown sugar
1.50 Lbs Dark Molasses
0.50 Lbs maple Syrup
5 oz. Northern Brewer (9% alpha, 60 min)
3.5 oz. Fuggle (4.5% alpha, 10 min)

What I don't have is their mash / fermentation schedule, thus part of the reason for my original inquiry.

**GuldTuborg** · 01-29-2012, 09:11 PM

Quote:

Originally Posted by Kershner_Ale

What I don't have is their mash / fermentation schedule, thus part of the reason for my original inquiry.

What is the OG and FG of the original?

Kershner_Ale · 01-29-2012, 10:57 PM

Quote:

Originally Posted by GuldTuborg

What is the OG and FG of the original?

Not sure, all I have is the ProMash calc sheet from my homebrew club. Club prez got the recipe from one of MSBC's brewers. Estimated O.G. is 1.108 on the sheet. The club brewed this recipe last spring and served it a few weeks ago at our club meeting, had been aging in whiskey and brandy barrels (1/2 batch split between both barrels) for several months. I tried both, very tasty but I'd only be guessing at F.G. based on my taste.