One of the world’s rarest brews, eisbock is not like a beer at all. It is reminiscent of brandies from France, cognacs and armagnacs, but with a malty character that’s unmistakable, a roiling estery aroma, and a forever lingering finish. Eisbock develops complexity over months and even years; a great eisbock commands immense respect.
   
Eisbocks are very rarely produced because they are expensive and must be aged. For the same reasons they make an excellent beer for homebrewing. The unwillingness of larger breweries to produce it maintains the mystique, and it makes a great addition to any brewer’s beer cellar.
   
Eisbocks (ice bocks) are the strongest of the bockbier varieties, starting with a strong doppelbock as the base. They are made using an ice process by which a beer is lagered at 32° F or below during the long secondary fermentation. The water within begins to freeze in the last two or three weeks as the fermentation ceases. At this point the ice is removed, thus increasing the concentration of the finished product by 5 to 10 percent.
   
These frozen elixirs are not to be confused with the multitudes of ice beers in your local grocer’s beer case. The mass-marketed ice beers serve their purpose but are nothing like eisbocks. Although more potent than most other institutional lagers they are, in fact, not bocks at all. Most of these types of ice beers are merely cooled to freezing temperatures during conditioning. Some are allowed to actually freeze to a very slight extent then filtered, which separates the beer from the tiny ice crystals that are formed. However, even in the latter example the effect is minimal compared with the authentic product. Most ice beers, in fact, are high-gravity beers watered down at the end of the process to increase the volume.

Was It All a Mistake?
   
Any discussion of eisbock should begin with the original, Germany’s Kulmbacher Reichelbrau Bayrisch G’frorns Eisbock. This beer is the standard by which eisbock is measured. The brewery was named for one of the 1846 founders, Reichel. The brewery was one of the primary producers in Kulmbach with a distinguished line of products. But the eisbock style is said to have been born of a mistake by one of the apprentice brewers who left some of the casks of doppelbock outside. The story, of course, ends well with the potent and delicious product becoming famed and unique.
   
The name eisbock was given to the beer much in relation to the German eiswein, which is made by pressing frozen grapes so that only the most concentrated portion of sugars and flavor are released. Well, as with most bock stories no one can really prove its validity, but it makes for good conversation to accompany the brew.
   
Reichelbrau has traditionally brewed the eisbock once a year at the end of August or beginning of September. After extensive aging the beer is honored at an eisbock festival at the local town hall on the last Saturday in March.
   
Unfortunately, just as this beer was beginning to gain popularity in the rest of the world, it was discontinued in 1996. The Reichelbrau brewery bought the local competitor, EKU (Erste Kulmbacher Unionbrauerei), and the eisbock fell to the wayside in lieu of the potent EKU Kulminator 28, named for the high starting gravity of 28° Plato (1.112 specific gravity). Similarly, the 24 percent on the label of the Reichelbrau betrays the 24° Plato (1.096) of its starting gravity.
   
The Kulminator is sometimes mistaken for an eisbock, and understandably so. The numbers for the beer place it squarely in the category for an eisbock. Furthermore, the beer undergoes a nine-month lagering process at 28° to 32° F, which  forms ice at the top of the beer during the last few weeks. However, the brewery dispels the notion that this beer is an eisbock and claims the amount of ice left behind is minimal.
   
The ice removed is supposed to clear the beer rather than concentrate it, but the difference is hard to see. It could be, though, that the brewery, in deciding to forego the original eisbock and stay with the Kulminator 28 doppelbock, wanted to preserve the integrity of the name eisbock. And in doing so the brewery may have simply chosen not to use the term in conjunction with the already well-established beer. It really seems to be a technicality, and perhaps EKU Kulminator 28 can be considered an eisbock just as easily as it can a doppelbock.
   
Those lucky enough have some of the 1995 and the final 1996 Reichelbrau vintage in their cellars. If not, get it if you can. The 1996 vintage produced 46,080 bottles, a total of 1,920 cases.
   
The Niagara Falls Brewing Co., a division of the Criveller Co. in Canada, is one of the only breweries in the world to produce the style on a regular basis. Subsequently, it has gained a certain amount of recognition in doing so. Beer writer Stephen Beaumont holds an annual Niagara Falls Brewing Eisbock vertical tasting, which is described in his World of Beer journal. The 1993 and 1996 are said to be the best of the last decade, with a warning of contamination in the 1994.
   
The Hair of the Dog brewery in Portland, Ore., has a beer called Eve, which is touted as an eisbock but is not produced commercially.
   
As a style by the numbers, the 1998 World Beer Cup guidelines list eisbocks as “German style eisbock” with original gravity of 1.092 to 1.116 (23° to 29° Plato), alcohol by volume of 8.6 percent to 14.4 percent, bitterness of 26 to 33 IBUs, and color of 18° to 50° SRM.
   
However, the strength and numbers of a bock do not make it an automatic eisbock, nor is this the only area to examine.

Malts and Mashing Techniques
   
Essentially, the first goal is to brew a strong bockbier to start the ball rolling. This means that you should follow the normal procedures for water treatment and grain selection. Due to the excellent technology in the malthouse, most two-row and six-row malt varieties are low in protein with high diastatic power, lending them to single-infusion mashes at 149° to 154° F. The mash should be allowed to convert for about an hour or until a starch conversion test indicates negative.
   
Pale malts consist of a mixture of pilsner and Munich, while specialty grains include cara-Munich 20° Lovibond and 60° Lovibond, carapils, and pale chocolate 170° Lovibond.
   
Kulmbacher Reichelbrau uses five malts, but pinning down the exact types and amounts is difficult. It most likely includes a heavy base of Munich, carapils, some tradi­tional light German crystal (like the 20° Lovibond), some dark German crystal (from 80° to 120° Lovibond), and chocolate malt.
   
The EKU is made, oddly, of entirely pale malt varieties.
   
Sparge at 168° to 172° F to yield 168° F water in the grain bed during runoff to deactivate the enzymes.
   
All of the recipes listed here are formulated for a 90-minute boil with the exception of the extract versions, which may be boiled just 60 minutes because the syrup has been boiled previously. If for some reason you are not getting the extraction you need and the beer is lower than your target gravity each time, you may wish to consider
boiling longer. Keep the hop schedule the same.
   
The Reichelbrau has an original gravity (before concentration) of about 22° Plato (1.088). The Niagara is considerably less at a reported 15.3° Plato (1.061).

Hop Varieties
   
As with all bockbiers, use the traditional hops required and get whole flowers if possible. Hops are extremely important to the flavor and character of the beer, even in beers like these in which hops are not the focus. The quality will still show through if you are true to your beer.
   
Try German Northern Brewer or Perle for the bittering hops, with Hallertauer and Saaz for flavoring and finishing. Remem­ber that the hop contribution to these beers should be for balance.

Yeast Selection and Primary Fermentation
   
Yeast selection will be the same as if you were choosing a variety for any strong bockbier. Look for a type that gives authentic flavor and is capable of fermenting in high-gravity environments. The attenuation will also be a concern, as you will want the beer to finish in the 1.012 to 1.020 range (3° to 5° Plato) because you are eventually going to concentrate the sugar content. This could mean an attenuation of around 80 percent. But stick with traditional types such as Wyeast 2206 (Bavarian lager) or 2124 (Bohemian lager) or comparable strains, adding more if needed at key points in fermentation and lagering.
   
For the primary fermentation follow the Reichelbrau and EKU schedules of 10 to 14 days and 17 to 21 days respectively at typical lager temperatures. The Reichelbrau clone should be about 7° Plato (1.028) when it goes into the cold secondary and the EKU clone should be about 8° Plato (1.032) when transferring.

Concentration and Bottle Conditioning
   
Now that the beer has reached the target gravity and primary
fermentation is complete, it is time to concentrate the finished beer. The theory behind the process is simple. You are making the beer stronger by partially freezing it and removing the ice. The alcohol remains, because its freezing point (-173° F) is far below that of water. In addition to pure alcoholic strength, the residual sugars and complex fruit and Maillard (roasted) type grain flavors are enhanced.
   
Much care must be taken with this process, however. As the alcohol and malt flavors are concen­trated, so are the undesirable ester (fruity, solvent-like) and aldehyde (green apple) compounds, as well as fusel oil alcohols (spicy, fruity, wine-like). Products such as cider and wines are not recommended for this process because of these reasons. Fusel alcohols are more toxic than ethanol. High and low (heads and tails) fusel alcohols from cider are particularly dangerous.
   
The aging should be a slow process, not something that happens overnight. There are several reasons for this, primarily the reduction of volatiles that were not driven off during the relatively cool fermentation and the overall marriage of flavors.
   
Kulmbach Reichelbrau and the EKU Kulminator 28 are given a secondary at 28° to 32° F for as many as six months. During this time the gravity drops another four degrees Plato (roughly 16 specific gravity points) and fermentation essentially stalls or moves extremely slowly. The beer then begins to freeze.
   
At home a simple chest freezer and a Cornelius keg will do the trick. Some other very inventive methods of freezing the beer include sepa­rating it into smaller containers to fit into a standard freezer and even putting the beer right into a snowbank in the middle of winter. Again, you will want to pay particular attention to the temperature and the rate of freezing to prevent damage to your kegs and excessive ice formation in your beer. It is reasonable even to remove some of the ice as it forms to be safe.
   
Remember, even though the beer is cold, it is important to remain sanitary. Also, be sure to measure the volume of ice (melt the ice and measure the amount of liquid) you remove so that you are able to calculate the final strength of the eisbock. Once the top of the beer is frozen you can just as easily siphon or, in the case of a Cornelius keg, push the beer with CO2.
   
The long aging process will not only concentrate your beer but will help immensely to clarify it. In fact there may not be enough active yeast left to adequately bottle condition the beer. (If a sample of the beer is crystal clear, there is not enough yeast.) In this case simply add a fresh pack (one smack pack, not stepped up) of yeast before bottling, being careful not to introduce any excess air to the product during bottling. Usually, this step is unnecessary.
   
As with any bottle conditioning method, the yeast will metabolize what oxygen is in the beer, if any, but the yeast should not have to have access to a full-blown fermentation. These beers are finishing high in gravity and the bottles will explode if care is not taken.
   
To calculate the strength of the final beer, use this formula:

C = Volume (start)/Volume (final)

   
C is the concentration factor that is multiplied by the original gravity (before icing) to yield an “effective original gravity.” The final gravity can then be calculated as well, and the values run through an alcohol-by-volume formula to figure your octane. Of course a hydrometer reading will work, too. Warm the sample to room temperature and measure. To figure alcohol content use OG-FG x .1275. For example:

OG 1.096 (24° Plato) - FG 1.020
(5° Plato) = 1.076 or 19° Plato. So
76 x .1275 = 9.69 percent by volume.

Brewing or Distilling?
   
As far as legality goes, there have long been conflicting reports as to whether this process is distillation or not and subsequently requires a separate license. Such exercises can be exceedingly tiresome, so straight from the source: According to the BATF Federal Code of Regulations, remove the water and it is concentration; remove the alcohol and it is considered distillation.

Eis-PA?
   
Since concentrating doppelbocks by this ice process gives them more depth and character, doesn’t it make sense that you could do the same with other styles? The answer is yes, to a certain extent. Other styles are really good as “eis” beers, but for the most part the types that are best suited are the darker, malty varieties such as stouts and also big IPAs. In fact eis-IPAs are really good. However, it takes quite a while for the hop character to soften and, as with other strong ales, for the flavors to integrate and become more harmonious on the palate. But it would make an intense Christmas ale.

Gastronomic Experience
   
There really is nothing quite like eisbock, not even the strong ales that are so very worldly. It is a unique pairing beer because of its exponential flavoring and potency. Eisbocks are a great deal like port. The younger vintages are sweet and brash with an immature fruitiness. But those with age carry themselves in a stately manner, showing smooth, vinous alcohol character, warming esters, espresso, and nicely balanced sugars. Indeed, eisbocks will sometimes exhibit character just like wines: plum, oak, and smoke to name a few.
   
With this in mind you will want to pair according to the age of the beer. The newer vintages of up to three years will go well with rich desserts and decadent chocolates, candied fruits, and roasted nuts. The medium-aged vintages, say three to six years, will begin to dry out a bit, lending themselves to hearty entrees a bit more. Food such as broiled meats, fruit glazes, rich pan sauces, and smoked fowl are good complements. And eisbocks that have aged six years or more really start to develop character — if they have not fallen prey to some sort of contamination. The well-aged beers are excellent as drink to complement your meals and for special-occasion toasts, and eisbocks of any age go well with cigars.

Reichelbrau Doppelbock Base
(5 gallons, all grain)
   
This strong dopplebock will work perfectly as a base for your eisbock but is good on its own as well. It should yield an original gravity of at least 1.088 (22° Plato).

Ingredients:
• 11 lbs. pale Munich malt
• 1 lb. carapils or dextrin type malt
• 1.5 lbs. crystal malt, 20° Lovibond
• 2 lbs. crystal malt, 80° Lovibond
• 1 lb. chocolate malt
• 0.75 oz. Perle hops (7.3% alpha) for 90 min.
• 1 oz. Hallertauer hops (3.7% alpha); 0.5 oz. for 30 min.,0.5 oz. at end of boil
• Wyeast 2206 (Bavarian Lager), at least 1 pt. of starter

Step by Step:
   
Mash grains in 5.25 gal. water in a single infusion at 150° F for 60 min. Sparge with 168° to 170° F water to collect 5.5 gal. of wort.
   
Total boil time is 90 min. At start of boil, add Perle hops and boil for 60 min. Add 0.5 oz. Hallertauer hops and boil for 30 min. more. Add last 0.5 oz. Hallertauer hops and whirlpool. Chill to 45° F and pitch yeast starter. Oxygenate/aerate well.
   
Ferment at 45° F for four days, allowing the temperature to rise to 50° F on the fourth day. Continue to ferment for six to 10 more days or until the beer has reached 1.028 (7° Plato).
   
At this point the beer is ready to lager for the ice concentration.     Cool the beer to 28° to 32° F, fermenting down to about 3° Plato (1.012), and let the beer form ice on the top. This will take a few weeks. If fermentation ceases, you may have to jump-start it with some actively fermenting slurry as the Reichelbrau brewery does. Once the beer has reached 1.012 (3° Plato), bottle and age at least four weeks in a cool place until it is completely clear.
   
The amount of ice removed is up to you. The Reichelbrau Eisbock has about 7 percent taken, which is fairly low, but the original gravity of this beer is high to begin with. The higher the levels of alcohol and sugar, the longer the beer will age. But it will require a longer matu­ration time. Priming sugar should not be necessary because the final gravity is at least the post-fermentation 3° Plato after concentration. However, if there is not sufficient yeast in the beer, you may have to add a fresh packet before bottling.

Reichelbrau Doppelbock Base
(5 gallons, extract with grain)

Ingredients:
• 11 lbs. light malt syrup
• 1 lb. carapils or dextrin type malt
• 1.5 lbs. crystal malt, 20° Lovibond
• 2 lbs. crystal malt, 80° Lovibond
• 1 lb. chocolate malt
• 1 oz. Perle hops (7.3% alpha) for 60 min.
• 1 oz. Hallertauer hops (3.7% alpha): 0.5 oz. for 30 min., 0.5 oz. at end of boil
• Wyeast 2206 (Bavarian Lager), at least 1 pt. of starter

Step by Step:
   
Start with 5 gal. of water. Crush and steep the grains (in a nylon sack) at 150° F for 30 min. Drain the sack well and rinse the grain with enough 168° F water to make a total of 5.5 gal. Total boil is 60 min. Stir in syrup. At start of boil, add Perle hops and boil for 30 min. Add 0.5 oz. Hallertauer hops and boil for 30 min. more. Add last 0.5 oz. Hallertauer hops and whirlpool. Chill to 45° F and pitch yeast starter. Oxygenate/aerate really well.
   
Follow the same fermentation and lagering schedule outlined in the all-grain recipe.

EKU 28 Type Dopplebock
(5 gallons, all-grain)
   
This recipe uses entirely pale malts, just as the EKU, but do not worry. This beer has plenty of malty character and a surprising amount of color. Its 28° Plato (1.112) makes it a big beer no matter how you look at it.

Ingredients:
• 15 lbs. pale Munich malt, 10° Lovibond
• 3 lbs. pilsner malt
• 1 lb. carapils or dextrin type malt
• 0.75 oz. German Northern Brewer hops (8.5% alpha) for 90 min.
• 1.25 oz. Hallertauer hops (3.7% alpha): 0.75 oz. for 30 min., 0.5 oz. at end of boil
• Wyeast 2206 (Bavarian Lager), at least 1 pt. of starter

Step by Step:
   
If your mash tun is big enough, mash grains in 6 gal. water in a single infusion at 150° F for 60 min. Sparge with 168° to 170° F water to collect 5.5 gal. of wort. Final runoff gravity will be quite high, allowing for a small beer if desired. If your mash tun is too small, simply mash twice and combine the runoff wort from both before boiling. Keep the first wort above 140° F while waiting so that bacteria will not grow in it, possibly creating off-flavors.
   
Total boil is 90 min. At start of boil, add Northern Brewer hops and boil for 90 min. Add 0.75 oz. Hallertauer hops and boil for 30 min. more. Add last 0.5 oz. Hallertauer hops and whirlpool. Chill to 45° F and pitch yeast starter.
   
Ferment at 45° F for seven days, allowing the temperature to rise to 50° F on the seventh day. Continue to ferment for 10 to 14 more days or until the beer has reached 1.032 (8° Plato). At this point you can lager the beer for the ice concentration.
   
Cool the beer to 28° to 32° F, fermenting down to about 1.016 to 1.020 (4° to 5° Plato), and let the beer form ice on the top. This
will take several weeks. If fermen­tation ceases, you may have to kraeusen with some actively fermenting slurry. Once the beer has reached 1.016 to 1.020 (4° to 5° Plato), bottle, and age at least four weeks in a cool place until the beer is completely clear. Obviously this is a strong beer, so 5 percent ice removal should be plenty. Then again, some homebrewers are completely crazed and would enjoy a beer of 15 to 20 percent alcohol by volume.
   
Priming sugar should not be necessary as the final gravity is at least the post-fermentation 1.016 to 1.020 (4° to 5° Plato) after concentration. However, if there is not sufficient live yeast in the beer, you may have to add a fresh packet before bottling.
   
A beer this strong will really test the attenuative ability of your yeast. There will be a lot of residual sugar, but this is perfectly in style for the EKU.

EKU 28 Type Dopplebock
(5 gallons, extract with grain)

Ingredients:
• 18 lbs. light malt syrup
• 1 lb. carapils or dextrin type malt
• 1 oz. German Northern Brewer hops (8.5% alpha) for 60 min.
• 1.25 oz. Hallertauer hops (3.7% alpha): 0.75 oz. for 30 min., 0.5 oz. at end of boil
• Wyeast 2206 (Bavarian Lager), at least 1 pt. of starter

Step by Step:
   
Start with 5 gal. of water. Crush and steep the grains ( in a nylon sack) at 150° F for 30 min. Drain the sack well and rinse the grain with enough 168° F water to make a total of 5.5 gal. Boil time is 60 min. Stir in syrup. At start of boil, add German Northern Brewer hops and boil for 30 min. Add 0.75 oz. Hallertauer hops and boil for 30 min. more. Add last 0.5 oz. Hallertauer hops and whirlpool. Chill to 45° F and pitch yeast starter. Oxygenate/aerate really well.
   
Follow the same fermentation and lagering schedule outlined in the all grain recipe.

Mikoli Weaver is head brewer at Woodland Brewing Co., Seattle.