Imperial Stout Techniques

[jmccraney]

Hi guys love your show, long time listener first time caller. (or whatever the equivalent is a forum).

I'm preparing to brew my first imperial stout and am trying to get a handle on all the techniques I may need to make a kickass stout. I've heard it said that big beers are tougher, so I would like to figure out what I need to do make this beer come out right. I'll be using the Old Rasputin Clone recipe from BYO (extract) as I love the original but of course recipe suggestions from people who have brewed this are welcome as well.

So to get started, I'll list off some things I anticipate doing differently from my last few batches:

• Pitching yeast slurry harvested from my last batch, a pale ale brewed with Wyeast 1056. Yes, I will be using Mr. Malty's calculator to determine the proper amount.
• Oxygenate with pure oxygen for 30 sec. For the lower gravity beers this wasn't as big a deal, so I just splashed the wort thoroughly, but I'm sure the yeast could use the help here.
• Bulk condition in secondary for about 2 weeks.

In addition here are a couple specific questions:

• Will this aging be sufficient: 2 weeks in primary (or until gravity stabilizes and bubbling slows, whichever comes last), 2 weeks in secondary (or until I get around to bottling), 3 weeks in bottle (or until carbonated)? The recipe on BYO claims the aging in secondary is not necessary, but I've read up to 6 months can be helpful. Any recommendations or general guidelines?
• Will there be any difficulties with carbonation? I.e. should I pitch more yeast (and when)? Or will it take extra time to carbonate?
• When is it necessary to use high gravity yeast? I know 1056 has a tolerance up to about 10% as per the Wyeast website, but what are good guidelines for when and how to use high gravity yeasts?

I understand that 1.090 OG, this recipe is not particularly high gravity, so some of these issues may not arise, but I'm sure I will be brewing more stouts when I move to all grain, so I would love to gather a set of best practices. And hopefully other readers can benefit as well. Thanks in advance!

 

[MachineShopBrewing]

Fermentation temp will be important. You want to keep it under 68.

Also, just ferment it until it is done and the package the beer. There is no need to bulk age. You can age it in the bottles just fine and it saves you a transfer that could introduce oxygen which is your biggest enemy on a beer like this(all beer really) Fermentation with 1056 should take 2-3 weeks to complete and drop clear.

1056 is fine for this beer.

I understand that 1.090 OG, this recipe is not particularly high gravity

1.090 is really high gravity. In normal speak, anything over 1.050-1.060 is considered high gravity. In homebrewing circles things are a little skewed. But, to yeast, anything over 5-6% is considered strong and measures should be taken to ensure a good fermentation and proper health.

 

[orangemen5]

I would bulk age this beer. I've think it ages better and more consistently bulk aging than bottle aging. I just brewed a old ale and RIS both 1.091 and plan to bulk age 3-6 months then bottle condition for another couple months.

 

[RmikeVT]

Please please please listen to the people that posted before me! When I first started brewing I brewed a monster extract belgian tripel, pitched WL5xx right out of the tube, thankfully I aerated so it attenuated fine, but it fermented too warm, and I transfered to a secondary with a ton of head space and left it there for about 5 months.

Guess what, I got beer that tasted like sherry with rubbing alcohol dumped in it. Oxidized beer w/ fussels. Pretty Gross, to date it has been 1 or 2 undrinkable batches out of 30+ batches of beer (The other got some infection due to poorly sanitized racking equipment -- I used old star san -- didn't realize that was bad).

Make a big starter, if you can't do that pitch 1.5-2 packs of US-05, aerate your wort, and keep the temps between 65-68. I use a ghetto swamp cooler. I have an igloo cube that I fill with water and put my FV in, I regulate the temp with frozen 1L water bottles.

 

[SpeedYellow]

1056 can ferment this 1.090 piece of cake. 7 days if you use the proper size starter. You'll want fermentation temps (the beer, not the ambient) of low 60s if you want a clean profile. Imperial stouts do change quite a bit over time, I like 8-12+ weeks myself. But I prefer sweet imp stouts balanced with high hops, and sometimes additions like coffee and chocolate. Each of those factors calls for longer aging. And carbonation can take a long time. Heck, even if you force carb it can take 3-4 weeks!

Everything with imp stouts takes a while. That's part of the joy.

 

[jmccraney]

Fermentation temp will be important. You want to keep it under 68.

Always. Any reason why this would be more important on a big beer?

There is no need to bulk age. You can age it in the bottles just fine and it saves you a transfer that could introduce oxygen which is your biggest enemy on a beer like this.

vs.

I would bulk age this beer. I think it ages better and more consistently bulk aging than bottle aging.

Hmm... what I'm getting from this is that if I just want a couple extra weeks on it, carboy vs bottle is not a big deal and I should just bottle it to minimize oxidation. However, if I were to age it for an extended period of time (i.e. over a month) I would likely get more consistent results from bulk aging. That is of course assuming proper sanitation, and minimal aeration and headspace. I think for this batch I'll just stick with extended bottle conditioning, but this is good to know.

 

[zachattack]

Always. Any reason why this would be more important on a big beer?

Yes. Big beers will often have much more violent fermentations, which means the temperature can get out of hand if you aren't keeping an eye on it. And in a bigger beer, there's a greater potential for fusel alcohols since there's more sugar being eaten by the yeast.

Remember that beer temperature can be 5 or even 10 degrees above ambient during the first few days of fermentation. A water bath can help keep it from going nuts, just keep an eye on it.

For big beers it can help to ferment low initially to prevent fusels, then warm it up towards the end to make sure it attenuates. So you could hold it at 62 for 5-7 days, then when it starts to slow down crank it up to 70 and hold it there for the remainder.

 

[TrickyDick]

Not a IS brew, but what say you about the Belgians, who are reported to pitch low and let free rise to upwards of 80 for many styles?


TD

 

[zachattack]

That's the same idea, but they're also looking to maximum yeast character in most cases, so they warm it up a lot sooner. But pitching low is to minimize fusels, and then letting it rise is to ensure attenuation and make sure the yeast are cranking out plenty of delicious esters. Obviously the temperature and schedule is highly dependent on the strain of yeast. I doubt the Chico yeast would give you many desirable esters.

 

[thood6]

Always. Any reason why this would be more important on a big beer?

vs.

Hmm... what I'm getting from this is that if I just want a couple extra weeks on it, carboy vs bottle is not a big deal and I should just bottle it to minimize oxidation. However, if I were to age it for an extended period of time (i.e. over a month) I would likely get more consistent results from bulk aging. That is of course assuming proper sanitation, and minimal aeration and headspace. I think for this batch I'll just stick with extended bottle conditioning, but this is good to know.

I would go with an extended primary and then bottle. Something like 5-6 weeks.

 

[RmikeVT]

I would go with an extended primary and then bottle. Something like 5-6 weeks.

I plan brewing a RIS next weekend to be consumed Next Winter. My Schedule is as follows

1) Pitch ~400 Billion Cells (Yeast Calc) of WLP001 into 1.090 Stout and keep ferm temps between 60-65. Letting it get upt to ~68* towards end of fermentation.

2) Give it one month on Yeast, transfer to secondary onto 2oz medium toast french oak cubes (no spirits) and possibly some vanilla beans for 6 weeks.

3) Bottle, add some yeast energizer at bottling, I added a pinch the last time I bottled a big beer and it was carbed up in a week.

4) Bottle condition for 6 months.

 

[TBBrewer]

I like using a few packets of us-05 for my RIS as it keeps the cost down from using liquid yeast and is an easy replacement for 001 or 1056. You have so many big flavors going on that you will never know the difference. You could also pitch on washed yeast or a slurry from a previous batch. Just make sure to properly rehydrate the dry yeast if you are going this route.

 

[cgg]

My experience leads me to this:

1. Primary - 4 weeks
2. Transfer to 2ndary - age 1 month
3. bottle and leave it alone for as long as I can stand it - 6 months plus is best

1056 slurry will be fine, and I've never needed to add yeast at bottling.
Have fun!

 

[SpeedYellow]

Those of you saying to age for 6 months-- is that based on experience or just a plan of attack? Seems a bit unnecessary for a 1.090 stout to me. The last 1.094 stout I made (with 1056) definitely needed 3 months, but not 6.

 

[TBBrewer]

Those of you saying to age for 6 months-- is that based on experience or just a plan of attack? Seems a bit unnecessary for a 1.090 stout to me. The last 1.094 stout I made (with 1056) definitely needed 3 months, but not 6.

I just tasted a 1.09 impy I did and it tasted great at the 3 month mark. I would say 3 is adequate with proper yeast pitch and brewing techniques.

 

[jmccraney]

Yes. Big beers will often have much more violent fermentations, which means the temperature can get out of hand if you aren't keeping an eye on it. And in a bigger beer, there's a greater potential for fusel alcohols since there's more sugar being eaten by the yeast.

Ah, well put.

That's the same idea, but they're also looking to maximum yeast character in most cases, so they warm it up a lot sooner. But pitching low is to minimize fusels, and then letting it rise is to ensure attenuation and make sure the yeast are cranking out plenty of delicious esters.

To clarify, you're saying that fusel alcohols are produced primarily at the beginning of fermentation? You seem to know your stuff, any recommendations on a good, comprehensive book on yeast behavior? I've got the basics, but I'm sure there are more subtleties than I'm aware if.

Thanks to everyone for the input on aging. As the recipe claims no aging is necessary (and to prevent oxidation and infection) I will skip secondary and rely on an extended primary and bottle aging. I have read that in 5 gal fermenters, autolysis starts to become a real possibility (though not a guarantee) at around 6 weeks, so I plan on bottling at 3-4 weeks, then waiting 4-5 weeks for carbonation. At nearly 2 months from brew day, I anticipate this beer being more than palatable. Of course time will only improve things, so I'll make sure to brew enough to keep myself distracted so I can stretch the bottles out over the course of the year. Can't wait to see how it develops!

 

[looneybomber]

Those of you saying to age for 6 months-- is that based on experience or just a plan of attack? Seems a bit unnecessary for a 1.090 stout to me. The last 1.094 stout I made (with 1056) definitely needed 3 months, but not 6.

I've never made a <1.10 stout, but of the stouts I've brewed, they were drinkable at 3mo, but good at 6mo and got excellent at 9mo. After 1yr, they're still in that "excellent" range.