How to Brew an Eisbock – The Frozen Secrets Explained

by Steve Thanos | Last Updated: April 20, 2020

There are certain beer styles that homebrewers obsess over for long periods of time. I know I do.

Eisbock certainly is one of those white whales that homebrewer, Martin Keen has been trying to wrap his heads around for quite some time now.

He finally did it! Before we dive into the recipe, here’s a bit of history on this ever so elusive style….The Eisbock.

The Legend

The legend of the first Eisbock takes us back to the 1800s in Kulmbach, Bavaria at the Reichelbrau Brewery. After a long shift, an assistant brewer was instructed to bring in the barrel of Bock from outside. As the story goes, the assistant brewer was tired after a long day of work.

He decided it was wise to leave this task until morning since he did not want to have this barrel come crashing down upon him in the brewery. What’s a few hours anyway? What really could happen with that short time period?

What came of this, as the legend goes, is what was first thought of as a major disaster. However, it actually turned out to be a happy surprise. This once beautiful Bock Beir was now partially frozen.

One of the reasons why the Eisbock eludes many homebrewers and commercial brewers alike is due the expense, effort, and time that goes into brewing it. Also, the Bureau of Alcohol Tobacco and Firearms(ATF) has made a law against freeze distillation. However, there are reports of the ATF being aware of the craft brewers and turning a blind eye to such brewing practices. Conversely, there are no laws prohibiting 20% abv beers from hitting the shelves. This makes no sense to me either!

As I mentioned, Eisbock involves freeze distillation – brewing then freezing a beer to remove the water content and then increase the alcohol content and not to mention flavor. Begin with a normal Bock Bier recipe and brew as you normally do. In this case, a Doppelbock was brewed.

Grain Bill

Some argue that a straight up Doppelbock recipe is in order for an Eisbock. If this is the case, then look towards a heavy dose of Munich malt to carry to load here. Anywhere up to 90% Munich malt can do the trick here.

Adding a touch of Pilsner malt can contribute some nice sweet honey notes along with subtle biscuit notes that can carry this beer. Go light on the Pilsner malt here; no more than 10% of the grist.

The rest of the grain bill can be contributed by some light tossing of Crystal malt, or even CaraMunich. A touch of Carafa II for color can be added as well. I would also consider some Pale Chocolate to impart some color.

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Hop Schedule

Since this is a German beer, the hops should be primarily German Noble variety. Noble hops include Tettnanger, Saaz, Spalt, Halltertau. The hops do not really shine here. Sorry, Hop Heads! The hops are only here for a nice balance between the alcohol and malt sweetness that you will achieve from this tasty concoction.

As for hop additions, I would follow a simple schedule of 1 ounce at 60 minutes in the boil for bittering. I would then add an aroma addition at 20 minutes. Again, the sweet maltiness is what really shines here. The hops take a backseat this time.

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Yeast

German Lager strains that attenuates slightly higher is the direction you want to go for this beer. The main objective is to not end up with a beer that is overly sweet. Here are the choices:

  • Wyeast: Bohemian Lager 2124 or Bavarian Lager 2206
  • White Labs: German Lager WLP830 or German Bock Lager WLP833
  • Imperial Yeast: Harvest L17
  • Dry Yeast: Saflager S-23

No matter what yeast you choose for this brew day, a starter is a must. Check out Billy’s write up of yeast starters here or my write up of Propper Starter here. Along with a good one minute of aeration, a yeast starter gives you an added bit of insurance.

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Eisbock Homebrew Recipe

Grains

49% German Pilsner Malt 8lbs.

43% Munch II 7lbs.

6% Carafa II 4oz.

2% Caramunich III 1lb.

Hops

Perle 1.25oz 60 min.

Tettnang .05oz 20 min.

Yeast

White Labs WLP830 German Lager with a starter

Mash at 152 F(66°C) for 60 minutes

Boil for 60 minutes

Fermentation

A clean fermentation is what you are aiming for here. Any type of flaws or off-flavors will carry over to the finished concentrated beer. This will leave you very disappointed. Maintain your fermentation temperatures per the instructions with your yeast. Usually somewhere in the 50°F(10°C) range will do just fine here.

My friends over at Brülosophy would tell us that 66°F(18°C) is the magic warm-fermented lager temperature. I will leave that up to you.

If your yeast strain instructs for a diacetyl rest, please do so. I have had horrible experiences of not doing one and I still regret it today. Simply raise your temperature to 68°F(20°C) for about three days and this will remove much of the undesirable diacetyl.

Concentration

The freezing process is done for two reasons; first, for stronger alcohol content and secondly, for a more complex flavor profile by removing water content. Once you have performed your diacetyl rest, bring your beer down to lagering temperatures.

This can be achieved by bringing your temperature to 28-30°F(-1°C); as Martin explains in the video.

After your beer has been Ice will begin to form on top of the beer. You will need to either remove the ice from the top or remove the beer from the bottom, such as using a bucket with a spigot. A keg is probably the best vessel to use in this case.

This way here you do not have to worry about that pesky oxidation problem that we have all been concerned with lately. The whole lagering stage can take up towards a month to complete. Here is where your patience really pays off.

Style Profile

Here’s what the BJCP has to say about this style:

  • Appearance

Color is reddish copper to dark brown. Impeccable clarity. Head is off-white to ivory in color. Moderate to poor head retention.

  • Aroma

Strong alcohol but not too harsh. Strong dark fruit esters from the malt and no hop aroma.

  • Mouthfeel

Low carbonation with a full body. Warm alcohol warming, but should not be hot, harsh, or bitter.

  • Taste

Sweet malt taste, but not cloying. Taste of roast, caramel, chocolate and dark fruit. No harshness from the alcohol. No hop flavor. Bitterness only contributes to balance the alcohol and the large malt taste. Alcohol can contribute to a perceived dryness at the finish.

  • Food Pairings

Pairs well with meat, especially game birds such as smoked duck or peasant. Also works well with venison and slow cooked pork. Pairs well with gouda or limburger cheese; as well as German chocolate cake.

I have never brewed this style before. If you are so inclined to give this a try, I suggest splitting a batch of a Doppelbock. Ferement part of it until frozen and package the other half. It certainly would be a fun project to do with a few brew buddies.

Be sure to get you a brew partner the way that Martin looks at Hernan

Video Transcript: Today, we are brewing the beer that has always alluded us, the one that got away the Eisbock. We finally did it.

Boom!

Hi, I’m Martin Keen. I’m taking the Homebrew Challenge to brew 99 beers. I have with me. Hernan. Hernan, can you explain what is an Eisbock? So Eisbock we are doing today we’re going to start with a Doppelbock recipe. We’ll be cooling it down to nearly freezing and then we’re gonna concentrate and get the Eisbock out of the fermentor.

Yeah. So what we’ll end up with is a much more, I don’t wanna say distilled, but a much concentrated beer. Uh, then we start with “Rule of the water”. Yeah. Who wants the water? We’re just keeping the alcohol, the good stuff.

For these recipe we’re going to use 8lbs. of Germans Pilsner and 7 pounds of dark Munich Malt.

Yeah. And then on top of that, base malt, we’re going to add a couple of specialty malts, mainly for color, also for that sort of toasty roasty-ness that we want from the beer.

So that’s 1 pound of Caramunich III and 4 ounces of Carafa II.

So while we are mashing, we thought it would be fun to try a commercial example of this beer. And I was really excited that just a one day I stumbled across a commercial Eisbock and I’ve never seen one before and I think they’re easy to find. Have you ever come across one of these?

No, first time. Yep. So this is a, this is from Germany. It is 12 cents. I have no idea how old it was. It looks like muddy water. It looks up muddy water. It smells a bit like port to me. Something you know, some very, Oh yeah. It doesn’t smell like beer, let’s put it that way. Whew. Cruelty. That’s intense. Wow. Strong flavor, is very strong and he’s good, good, strong, good. It’s, it’s not nothing, it’s just too much.

I couldn’t imagine drinking a whole bottle by myself of this. It’s a desert beer.. Yeah, like sipping desert. We are brewing four and a half gallons of this thing. I mean, yeah, I’d be happy to if we get to something of this character. All right, back to work man, back to work.

All right, so let’s talk about the hops for this beer. We are going for an IBU of 30. The way we’re going to get there is with some German Nobel hops.

So I have here at 1.25 ounces of Perle hops.

Those go in at 60 minutes and then a 20 minutes I will add half an ounce of Tettnang, and in fact it’s time to put the perle in now.

The yeast for this beer is just like the previous duffel bot we made.

It’s 2308, which is Munich lager. Add this at 50 Fahrenheit.

So I think that was the easy part done. Uh, we will let the beer ferment, uh, cold crash it, move it into a keg and that point, turn it into an ice beer.

Now its clean up time.

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We Cleaned up!

So it’s been about seven weeks since brew day. That beer, once it got done was cold, crashed and then transferred into a keg where it’s been sat at 35 Fahrenheit for weeks. This morning I moved that keg into this chest freezer here, which is set to -3 Fahrenheit.

So I think this is the part that’s really a bit of a balancing act because while we want to freeze the beer to condense it, I don’t want to completely freeze the kegs and I think comes out and that is exactly what happened the first time I tried to brew an Eisbock.

Now I read online that about 10 hours is optimal to get this thing where we want it to be. So this has been in here for 10 hours now. Is it ready? Is there enough ice built up without freezing the whole thing? Well I think the best way to find out is to give it a shake. Can you hear that? It sounds really slushy.

Think it might be ready.

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Yeah, I’m going to give this a shot. I think this is close and I don’t want to completely over freeze this. So what I have prepared is a keg to move the beer into. I filled this with starsan and and then pumped all the starsan out. So this is now a sanitized empty keg.

Just need to purge it as well. So I will now connect, um, a liquid post from the Eisbock keg into this fresh one and start transferring.

Well, I think we’re getting pretty close to done here. This is, uh, about halfway full. We started with 4 gallons. Uh, this one, when I shake it now I can feel there’s ice there, but not hearing any slushy sounds now. So I think that’s all of the Eisbock concentrate that I’m going to get.

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Tastes like “Beery” water, which I guess it was about right because we really want all the alcohol and the flavor in that other keg. Not bad though.

I don’t know if I’ve ever been so excited for a tasting as this one. This has been years in the making. So at this point, normally I share some fermentation notes about like what the ABV is of this beer. Well a, it was an 8% beer before we froze it. So, um, I think maybe sort of 11%, we’ll see how well yeah, to me the biggest thing I noticed was that significantly darker than the Doppelbock that we had last week.

All right man. Let’s go for it. Let’s go for the taste. Our first ever Eisbock. Cheers. If the other one was liquid bread, this is less liquid bread. More just more like straight up bread. Well it definitely is richer, right? Yeah. Yeah. Um, nothing overpowering.

It’s rich, um, rich beer, but it doesn’t feel heavy when, when you’re drinking it. Somewhere, Kind of a sticky, come on at the end and then there’s all the caramel-y profiles in between.

I wonder what this will taste like with a bit of age on it because already it is quite complex and thick and tasty. Yes, baby’s going to get better. It needs to age. Theres still some strong sweetness to it. Not overpowering, but um, that is only going to get better.

So this is what is left of the beer after it was frozen. This is what was frozen and is now thawed out. So I was expecting this to look super watery. Lighter. Yeah. But it’s dark as anything. It looks watery, but let’s get a, let’s get a glass. All right. Don’t try this at home.

I actually did try it and frozen for them and it was just the last year. It was very, yeah, it was, it was like a, a watery slushie with a slight beer favor. So we’ll see what it’s like warmed up against the light. Yeah, I can totally see through. Yes. So that’s a really good sign.

Yeah. But it’s a sign that we pulled out the good stuff. Um, Oh, it doesn’t smell great either. Oh yeah. No, I’m not sure I want to try this. I’ll let you try it. Thank you. Cheers.

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Well, it doesn’t taste bad. It doesn’t really taste, it doesn’t smell good, I’ll tell you that. No, no. It tastes like nothing, nothing. These, yeah, bye-bye Porter. I’ll drink this all winter. This is the taste of success. Cheers, cheers mate!

Eisbock Recipe Recap:

  • 8 lbs Pilsner; German
  • 7 lbs Munich II
  • 1 lbs Caramunich III
  • 4.0 oz Carafa II
  • 1.25 oz Perle Pellets – Boil 60.0 min
  • 0.50 oz Tettnang Pellets – Boil 20.0 min
  • 1.0 pkg German Lager White Labs #WLP830

Home Brew Equipment:

I am the former President of my homebrew club, Plainfield Ale and Lager Enthusiasts (PALE) in the western suburbs of Chicago, IL. I brew on my BIAB system with my incredibly patient and understanding wife, adorable 9 year old daughter, and 12 year old brew dog.