Eisbock Freeze-Distilled Doppelbock

In the most recent BJCP style guidelines of 2021, Eisbock has can be found under Category 9 Strong European Beer which contains more strongly flavored and higher alcohol lagers from Germany and the Baltic region. Most are dark, but some pale versions are known. The Eisbock style has its own subcategory 9B -Eisbock.

Eisbock literally translates as an “ice” bock style of beer (the word “eis” is German for ice) and is a super strong beer that uses a technique of freeze distillation to concentrate the alcohol and flavors of a Bavarian bock beer.

Although an Eisbock typically has an ABV that goes well above the 7% of a traditional bock beer, it normally stops at around 12% – 15% ABV.

Any beer can use a freeze distillation process to make it stronger, whether its an ale or lager from any beer culture, but in Bavaria, home of the Eisbock, nearly all beers of this style are traditionally made using a barley-based strong lager, often a Maibock produced in the cooler winter months

Kulmbacher Eisbock Bier

A noticeable exception to the barley-based Eisbock is an ale that uses the wheat-based Weizenbock as a starting point.

One of the most famous examples of a wheat-based Eisbock is the Aventinus Eisbock made by the Schneider Weisse brewery on the banks of the Danube in Kelheim, Bavaria.

Only produced once a year, just before Christmas, the Aventius Eisbock is a freeze-distilled version of its famed Aventinus Weizenbock. With an already substantial ABV of 8.2%, the Eisbock version turns it into a formidable 12% ABV ale.

Stronger than a traditional bock (6.3% to 7.6% ABV) or even a Doppelbock (double bock) at 7% -12 % an Eisbock is the strongest beer that falls into the category of bock beers (bockbier).

The Magic of Freeze Distillation

Photo by Erin McKenna on Unsplash

The freeze distillation process works as water freezes at 32ºF (0ºC) whereas ethanol only freezes at the much lower temperature of -173.2ºF (-114.1ºC).

As the water freezes, the liquid alcohol is left behind and the finished beer is much stronger than before the distillation process.

The amount of the increase in an Eisbock’s ABV depends largely on to what extent the temperature of the beer drops below the traditional freezing point of 32ºF or ºC.

In commercial breweries, an Eisbock is traditionally chilled to approximately 25 to 28ºF (-4 to -2ºC) which results in about one-quarter of the beer’s water content freezing.

Eisbocks which are traditionally brewed in Bavaria will tend to have an ABV of 9% to 14.5%, and rarely stray much further.

The freeze distillation process has, however, been known to produce beers with an alcohol content of over 40%, the most famous example being the world’s strongest ice beer “Strength in Numbers”, which was produced by a collaboration between Shorschbrau of Germany and Brew Dog of Scotland.

The two rival breweries had competed with each other in the early years of the 21st century to produce the world’s strongest beer. Strength in Numbers was created using traditional ice distillation, reaching a final strength of 57.8% ABV.

If you are brewing an Eisbock at home you can easily calculate the approximate alcohol by volume of the finished beer with the following equation:

V1 x ABV1 / V2 = ABV2

V1 = The volume of the batch of beer before freezing.

ABV1 = The ABV (as a percentage) of the beer before freeze distillation.

V2 = The yield or volume of the drained beer after freezing has taken place.

ABV2 = The ABV of the finished Eisbock after freezing.

To help illustrate this equation, let’s use an example:

If a 5-gallon (19-L) batch of bock with 7% ABV yields 3.75 gallons (14.25 L) of finished beer after freezing, the ABV of this Eisbock is:

5 x 7% / 3.75 = 9.3% ABV

Another of those beer styles which was supposedly created by accident, the Eisbock certainly has an interesting story behind it.

Although nobody knows how much of the myth of the discovery of the first Eisbock is true, it has a certain charming quality anyway, reminiscent of the European fairytales of yesteryear.

The Origins of the Eisbock Beer Style

The legend of the Eisbock is often thought to have started by accident in the town of Kulmbach in Franconia, Bavaria.

The local Reichelbräu brewery claims on a cold winter’s night in 1890, a young brewery worker was finishing up his working day of heavy toil shoveling spent grain, moving barrels indoors, and other general cleaning tasks.

When ordered to move a barrel of barley-based bock beer from the brewery yard to a warmer place elsewhere in the brew house he failed to do so, whether through forgetfulness or just being too worn out, but the barrel of beer remained outside all night.

What harm could it do to the beer, right?

The next morning, the beer had all but frozen. Well, the water content had, anyhow. The ice inside the barrel had expanded to such a degree, the wooden staves off the barrel broke and busted off.

Later that day, when the head brewer returned to work, he found the busted open barrel and noticed that the block of ice that had been inside it encapsulated a small amount of a residual dark liquid.

Rumour has it the young brewery worker was made to drink the darker liquid as a punishment, but as the head brewer realized how much the boy was enjoying this new drink, he tried it himself, and hence the style of an Eisbock was born.

Although nobody can confirm for sure whether this myth is true or not, it’s certainly the way the story is told in the sleepy town of Kulmbach – it almost has a fairytale-like quality to it.

Riechelbräu soon took their Eisbock to the beer market and “Kulmacher Eisbock” (also referred to as “Bayerisch G’frorns” meaning Bavarian ice cream) is still one of the best-selling Eisbocks commercially available today.

Eisbock Beers in the US

Eisbocks gain their strength from being frozen near the end of conditioning and the water ice being removed.

In the resulting beer, the alcohol concentration increases to nearly 12% ABV, about twice as much as a typical German lager. Because they are still bockbiers, Eisbocks have all the characteristics of a typical strong beer. They are much maltier and smoother than even the Doppelbock biers.

In Germany, you will find this beer is exemplified by G’frorns, which are brewed in the northern Bavarian Kulmbacher AG, (the reputed brewery of origin of the Eisbock style).

These beers are best when sipped in a brandy snifter like Sherry, Port, or Madeira. Eisbocks can be made as a lager with barley, like the Reichelbräu G’frorns, or as an ale with wheat, called Weizen-Eisbock.

The Weizen-Eisbock that is most often available in North America is Schneider Aventinus Eisbock, which has a 12% ABV.

Many craft brewers, both home-based and commercial have enjoyed experimenting with the Eisbock beer style and other freeze-distilled beers, with some of the finished beers reaching over 40% ABV.

Unfortunately here in the US, it is very rare to find many commercially brewed Eisbocks due to alcohol laws that put freeze-distillation or fractional freezing on par with other forms of distillation.

According to Ruling 94-3 of the Bureau of Alcohol Tobacco and Firearms (ATF), the process of freezing a beer to remove more than 0.5% of its original volume is illegal without a license.

It seems crazy that in this day and age you can brew a beer to 20% ABV with no problems but freeze-distilling a base beer to make a finished beer of 12% is still not allowed!

However, some craft breweries in the US have produced limited-release Eisbergs including the exemplary Colorado Team Brew “Warning Sign”, Mammoth Brewing’s “Fire & Eisbock” and Jack’s Abby “Bourbon Barrel Aged Eis Maker.”

It seems it may be illegal to brew these freeze-distilled beers but the ATF is turning a blind eye.

Oh, and a quick and important note – please don’t confuse these Bavarian beer specialties, such as the Eisbock, with the US craze for “ice” beers which saw almost every macro brewery and even some of the larger commercial brewers producing “ice” beers in the mid-1990s.

While the freezing process may be similar, for beer fans the results were worlds apart, by comparison.

The word ‘ice’ was used by the big brewers mainly as a marketing gimmick that would allow them to feature impressive advertisements featuring exploding blocks of ice with bottles of “ice” beer suspended inside.

The big beers like Molson Ice, Bud Ice, and Labatts Ice basically took their already dull and lifeless beers and froze them to just below freezing point to remove very small amounts of water, supposedly creating an even smoother, but still dull and lifeless, beer.

By comparison, the result of freezing a traditional specialty beer like a bock creates a much smoother, deeper, and more complex beer with a nice warming alcohol effect.

Style Guidelines

Although much of the information below comes from the latest BJCP guidelines, if you are revising for exams it is always advisable to check out the BJCP website to check if any updates have been made to the style guidelines.

Overall Impression

The BJCP describes the Eisbock as a strong, full-bodied, rich, and malty, dark lager from Germany. With a viscous quality and stronger flavors, even referred to as concentrated, it should have a smooth and warming alcohol taste rather than burning.


An Eisbock is most often a deep copper to dark brown color, sometimes with attractive ruby highlights. Good clarity is the norm, although Eisbocks which use a basic wheat beer, a Weizenbock, may have a slight haze associated with the style.

Head retention will normally be moderate to poor as you would expect from such a strong ABV beer. The head will normally be off-white to a deep ivory color.


A rich and intense malt profile is balanced by a strong alcohol presence. The malt will often have bready or toasty qualities, with some caramel or faint waft of chocolate, often with notes of dark fruits such as plums or grapes.

There should be no hop aroma present and the alcohol aroma shouldn’t be too harsh or solventy. A clean fermentation profile is evident in the aromas.


Sweet, malty flavors are backed up by a significant alcohol presence. The malt may have Maillard products, toasty qualities, some caramel, and occasionally the slightest waft of a chocolate flavor.

Dark fruit esters may be derived from the significant malt content. A hop bitterness is slight with just enough to offset the malt sweetness and avoid a cloying beer.

No hop flavors are normally detected, with the alcohol helping to balance the stronger malt presence. The finish will be a rich malt with some dryness from the alcohol. An Eisbock shouldn’t be too sticky, syrupy, or cloyingly sweet.


Full to very full-bodied with a low carbonation level. there should be a significant alcoholic warmth without too much of a sharp burn. Very smooth and silky without harsh flavors from alcohol, bitterness, or other concentrated ingredients.

Characteristic Ingredients

Traditionally the same as a Doppelbock, with Pils, Vienna, and Munich malts commonly used. Occasionally a dark malt will be added to fine-tune the color. Being a German beer it tends to use German hops like noble hops and clean German lager yeast.

Wheat malts will be the base malt for an Eisbock which uses wheat beer as its base beer before freeze distilling.

Vital Statistics

IBU25 - 35
SRM17 - 30
OG1.078 - 1.120
FG1.020 - 1.035
ABV9% - 14%

Brewing Tips:

To brew a good Eisbock bier, you can’t just brew a strong Doppelbock and then concentrate it by freezing. The resulting beer would be way too sweet and cloying with super strong caramel and bready malt flavors.

When you brew a Doppelbock that is on the upper end of the style in alcohol content, the resulting beer may turn out to taste like sweet cleaning fluid.

According to Jamil in Brewing Classic Styles 80 Winning Recipes Anyone Can Brew, you must reduce the caramel and Munich malts and use yeast which attenuates well for the beer to come out balanced.

It’s best to keep the water loss around 10% and never more than 25% in order to keep the alcohol smooth, and not harsh or burning.

It is key to first brew a Doppelbock that is in balance with subtle flavors. Once the beer is freeze-distilled, any flaws will become abundantly evident.

You will most likely need a long conditioning period for the alcohol and flavors to mellow. Follow these guidelines and you should be able to make a great Eisbock.

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