Another Extreme Beer

News broke this week of another entry into the race to create the strongest and most extreme beer on the commercial market. Scottish brewer BrewDog, currently the largest independent brewery in Scotland, recently announced the release of a 32% ABV imperial stout aged in whisky casks quizzically named Tactical Nuclear Penguin.

Aside from bragging rights used in marketing, high-gravity extreme beers are quite an accomplishment and a testament to the skill of a brewer. Alcohol is a toxic substance (hence the root word for intoxication), especially to microorganisms. Even though their entire existence is spent converting sugar to alcohol and carbon dioxide, most yeast strains cannot survive as their environment approaches 10% to 12% alcohol by volume.

So how are such high-gravity beers made? The first step is in the choice of yeast used, and some brewers have developed their own robust yeast strains in their house laboratories. Even so, these specialized species cannot achieve the record-setting levels of 25% ABV or above without a lot of prodding from the brewer.

Such a batch begins with making a very large starter, which is a type of mini-brew used just to increase the cell count of the yeast before introducing it to the wort. Homebrewers will commonly make a starter out of nothing but sugar, yeast and water, allowing it to grow for hours or days before brewing. The greater number of yeast cells that can begin fermentation immediately when introduced forgoes a lot of other problems as well.

The second consideration is to use highly fermentable grains, that is, grains with abundant starch content that can be fully converted and fully attenuated by the yeast. Likewise, fermentation is given another starting boost by highly oxygenating the wort once the yeast has been pitched, generally by agitation or even bubbling pure oxygen through the liquid.

Fermentation will naturally proceed quite vigorously at first and will begin to slow after a certain point, eventually coming to a halt once the consumable sugar content has been depleted. For that reason, brewers of high-gravity beers will continuously make small additions of sugar to feed the yeast and keep it alive and active, sometimes for weeks or months.

Eventually, any ale or lager yeast will reach its limit of survivability as the alcohol levels continue to rise. Thus, brewers will sometimes switch to other strains of yeast in later stages to finish off the fermentation to the target levels. Champagne yeast is a favorite alternative, as it is highly tolerant to alcohol and neutral in flavor.

However, BrewDog used none of these methods in brewing their record-setting beer, instead relying on a bit of a brewing cheat. Although water freezes at 0°C, ethanol does not freeze until −114°C. By freezing the wort after fermentation, the water content will freeze into a solid block of ice that can be easily removed, leaving behind the unfrozen alcohol in a much stronger beverage.

This method of freezing and removing the water is used in producing the German beer style eisbock, strong beers of about 16% ABV so named after this process. BrewDog did not actually brew a 32% beer but instead made a 10% imperial stout that was held at −20°C for three weeks. The result may be the same in the final product but the achievement is far less impressive than actually coaxing and manipulating yeast to perform far beyond their limits.

Extreme Beers

Brewing lends itself to experimentation in the same way as cooking up a recipe in a kitchen. Ingredients can be used or featured based on their individual strengths and flavors, their seasonal availability or to the taste of the chef. And as always, limits and prescribed recipes exist only to be pushed, challenged and extended.

The American craft brewing scene has an element of rogue extreme beers galloping along its fringes. What is meant by “extreme beers” are certain craft beers that push the limits of style guidelines, palatability or alcoholic strength. These are almost by definition experimental products, some little more than commercial test batches that have been formally released.

The descriptor "extreme” is taken to mean beyond simply the stronger versions of more traditional styles. Strong IPAs and imperial stouts may creep into the 10% ABV range but extreme beers routinely double this. Yet it is not necessarily the gravity that defines an extreme beer but some attribute taken to excess beyond any contemporary product or stylistic guideline.

By their very nature, extreme beers can be expensive and calorie-laden. Anywhere from twice to ten times the ingredients of a normal batch of beer can be used to produce just a single batch of these beers. This makes their prices soar, and small batch runs yield limited availability that is only compounded by rabid fans and consumers.

Because extreme beers are such a financial commitment on the part of the brewer, only a few brewers have the means to even attempt these rarities. Likewise, only a subset of the craft beer consuming market is willing to invest in these beers, yet somehow demand remains very high nationwide. Some present commercial examples include:

Three Floyds Dark Lord Russian Imperial Stout. This is a dark imperial stout that pushes the limits of viscosity. At 13% ABV, this stout is as thick as sorghum and has elements of coffees, chocolates and ports. A special day is set aside each April for its annual release that draws pilgrims to the brewery in Indiana from across the United States.

Dogfish Head World Wide Stout. This is another Russian imperial stout that has traded places back and forth with the Utopia in years past for the world record of the highest gravity commercial beer. Generally around 18% ABV, this is another heavy stout with components of roasted coffee, merlot, dark fruits and licorice.

Samuel Adams Triple Bock. Batches of this extreme beer were brewed only in 1994, 1995 and 1997, yet bottles can still be found in retailers around the country. An experimental (and somewhat controversial) extension of the doppelbock style, the Triple Bock reached 17.5% ABV and has been described as everything from a heavily malted ale to an unpalatable blend of soy sauce and wine.

Dogfish Head 120 Minute IPA. Supposedly a continuation of their sixty- and ninety-minute hopping process from the beers of the same names, this is less a strong IPA and more of a hoppy American barleywine. Recent batches have clocked in at 21% ABV, and this beer is designed to age in the cellar for decades or longer. Trust me when I say this beer greatly improves with even just a little age.

Samuel Adams Utopia. The most extreme of commercial beers, this beer requires several different yeast strains to reach its final gravity of 27% ABV. Sold in a very distinctive gold vessel modeled after a full-sized mash tun, a single bottle can retail for as much as $125. Remarkably, the beer remains smooth and drinkable without becoming whiskey-hot with the highest alcohol level ever recorded for a commercial beer.