When the average beer drinker hears the words “Ice Beer,” he or she most likely remembers when macro-brewers first introduced this concept to young drinkers in the 1990’s. For those of us who were in college at the time, “Ice Beer” represented an opportunity to consume more alcohol without spending much more money, and the brands that surged in popularity certainly reflected that fact. Canned swill like Icehouse and Natural Ice offered co-eds the most booze for their buck, but didn’t really deliver much more flavor than standard American Lagers.
20 years later, while college students still funnel beer down their throats by the dozen, home brewing enthusiasts tend to concentrate more on aroma, flavor, and mouthfeel than alcohol-to-dollar ratio. Despite any stigma it may have, however, partial or “fractional” freezing of beer is actually quite relevant to the home brewer and very easy to perform at home. There are a couple different ways to go about freezing your home brew, both of which can produce very desirable results in the finished product.
First, there is a practice that is often referred to as "Ice Stabilization,” where the brewer allows a small amount of ice particles to form in the beer (usually around 5%), and then skims them off before bringing the beer back above the freezing point. The ice particles will contain mostly water, which raises the alcohol level of the beer slightly, but also traps haze-forming particulates and assists in the fining process of the beer. The result is a beer with better clarity, better stability, and what many brewers also believe to be an improvement in flavor as well.
The second, more dramatic freezing procedure is called “Ice Distillation.” For this process, much larger amounts of beer are allowed to freeze and are then removed, drastically increasing the alcohol content of the brew and completely changing the flavor profile. Perhaps the most historically renowned example of this brewing method is the Eisbock beer style, which involves partially freezing a traditional German Doppelbock to achieve an ABV anywhere from 7-33% with much more concentrated flavor. In recent years this practice has garnered newfound attention as it has been used extensively by the Scottish craft brewery BrewDog to produce very alcoholic, flavorful beers well outside traditional style guidelines.
To “ice distill” a beer at home, try freezing approximately 10-20% of the brew, and then rack the remaining liquid off of the frozen material. Eisbocks and other ice distilled beers typically will benefit from a period of aging following the freezing process. Also, keep in mind that the more of the beer you freeze, the smaller of that frozen portion will be water, so start with a small amount and adjust as needed. Lastly, it is best not to freeze a hefty portion of a rich, malty beer as the result will be unbalanced and cloying – for the best results, back off on your specialty malt additions when brewing the base style.
Good luck and happy brewing!
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