How to Brew an Eisbock: Thawing the Cold Magic Secrets of Germany’s Strongest Brew

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.

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.

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.

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

Directions

1. Mash at 152 F(66°C) for 60 minutes
2. Boil for 60 minutes

Save this for Later

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. Ferment part of it until frozen and package the other half.

It certainly would be a fun project to do with a few brew buddies.

Frequently Asked Questions

How to make ice beer?

To make ice beer, one would typically start by brewing a strong lager or ale, and once the beer has undergone primary fermentation, it’s subjected to a process known as freeze distillation.

This entails freezing the beer and removing the ice that forms, which concentrates the alcohol and flavor in the remaining liquid. The process can be repeated multiple times to achieve the desired concentration.

The resulting beer is known as an Eisbock in Germany, where this technique originated. The key aspect of making ice beer is the freeze distillation process which concentrates the beer’s alcohol and flavor.

What is Bock beer?

Bock beer is a strong lager that originated from the German town of Einbeck but became popular and further developed in Munich.

It’s characterized by its malty sweetness, minimal hop bitterness, and a robust body. The color can range from light amber to deep brown, depending on the specific style of Bock being brewed.

There are several types of Bock beers, including Traditional Bock, Maibock, Doppelbock, and Eisbock, each with its unique attributes and brewing requirements.

What kind of beer is Bock?

Bock is a category of German lager, with its sub-styles varying in color, strength, and flavor. It’s known for its malty character, minimal hop presence, and a hearty body.

The various types of Bock beers include Traditional Bock, Maibock, Doppelbock, and Eisbock, with Eisbock being made using a process of freeze distillation to concentrate its flavors and alcohol content.

Can you freeze a lager to make Eisbock?

Yes, you can freeze a lager to make Eisbock. The process involves brewing a strong lager and then freezing it post-fermentation.

By removing the ice that forms, you are left with a concentrated liquid known as Eisbock, which has a higher alcohol content and a more robust flavor profile compared to the original lager. This process of freeze distillation is essential in creating Eisbock or ice beer.

Is freeze distillation legal and safe for making Eisbocks?

The legality and safety of freeze distillation can vary by jurisdiction. Some regions may have regulations against freeze distillation due to its ability to significantly increase the alcohol content of the beer.

It’s advisable to check the local laws and regulations concerning alcohol production and freeze distillation before attempting to make Eisbocks or any other type of ice beer.

As for safety, when done correctly, freeze distillation is a relatively safe process, however, ensuring that the equipment used is clean and well-maintained is crucial to prevent contamination and ensure a safe brewing experience.