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Eisbock: Style Profile

It is amazing how rich our memories can be. Every time I think about eisbock, several moments in my life leap to mind, complete with flavors and aromas. I recall the time I was sitting at my friend Steve’s kitchen table, tasting beers and discussing the failure of judges to award a perfect score of 50 points to any beer. During our conversation, Steve poured an eisbock he had brewed nearly five years earlier. It turned out to be not only the best eisbock I had ever tasted, but also one of the best beers I had ever tasted. I exclaimed, “Now this is a 50 point beer.” It was a perfect, flawless eisbock. Steve later entered that beer into a competition and the beer took first place, but of course, no judge awarded it a perfect score. What a shame the judges could not let go of their fear of being wrong long enough to give the credit due to a perfect beer.

Eisbock is a strong, rich lager with a big malt character. It ranges in color from deep copper to dark brown. All bock beers have a lot of bready and toasty malt character, but that does not mean they are overly sweet. An eisbock should not be under-attenuated, but the low hopping rate results in a balance toward the sweet side. The alcohol present should be warming, but should also be smooth and never hot or solvent-like. The fermentation character is clean, although freeze concentration is going to emphasize what esters are present. Some examples will exhibit, through a combination of malts and alcohol, a fruity, grape or dark fruit character.

A great eisbock recipe is relatively simple, but many brewers start with a far too big and complex base. You cannot start with a doppelbock recipe and make a perfect eisbock. You must take into account the freeze concentration step, which increases all of the flavors from the base beer. If you start with an over the top malt, caramel, and alcohol character, you will end up with a beer that needs to be served in a thimble. Keep in mind that all German-style beers are easy-drinking and eisbock should be no exception.

Start your recipe with high quality continental Pilsner and Munich malts. You can use other base malts, but the light, grainy and bready taste of high quality Pilsner and Munich malt is right on target for this style. While a doppelbock should have Munich as the bulk of the grist, for eisbock you will want Pilsner to make up the majority of your grist, approximately 50 to 70% is good. Munich malt is still a large portion of the grist, ranging from 25 to 45%. How much depends a lot on the character of the Munich malt you use. Generally, the darker the Munich malt the less you will use. Of course, there are Munich malts at lower color levels that have far more flavor and aroma than lesser quality dark Munich malts. I like to use Munich in the 8 to 10 °L range for 40% of the grist. The last malt needed is some caramel malt. This is often where many new brewers go astray. Too much and the beer is cloying. Too little or too light a color, and the beer ends up more like hard candy dissolved in alcohol. You can experiment with different color levels and percentages, but 5% of a mid-color (40 to 80 °L) caramel is going to be close to ideal. You should be able to make an excellent example of the style with just those three malts. Usually, this is the point where I say that you can experiment with other malts to add more character, but in this instance, don’t. It just becomes too much, too heavy. While you want rich melanoidin flavors that specialty malts can provide, adding more will often make the beer taste meaty or brothy.

Extract brewers will need to use a Munich extract or do a partial mash with Munich malt. Most Munich malt extract is a blend of Munich and Pilsner (or other pale malts) in different percentages. Many of the Munich blends out there should work fairly well for this beer, but let flavor and freshness be your guide rather than the percentage of Munich in the blend. The only supplier of 100% Munich extract I am aware of is Weyermann. If you can get 100% Munich extract, then you can blend it with a Pilsner malt or pale malt extract to get the right proportions. However, I do not think it is worth the effort in this case.

I like to avoid any work that I do not feel improves a beer, so I prefer a single infusion mash. Perhaps, historically, a brewer would use a decoction mash when brewing most German-style beers, but I find that high quality continental malts, a single infusion mash, and excellent fermentation practices will produce a beer that is every bit as good as the best commercial examples. It is far more important to invest time and effort in fermentation, sanitation, and post fermentation handling than on decoction. If you have ensured that all of those other aspects of your process are flawless, then decoction might be something of interest. For a single-infusion mash, target a mash temperature range of 152 to 156 °F (67 to 69 °C).

At most, hop character is just a background note in eisbock. This beer is about rich malt character and a fine example requires no hop character. If you do like a touch of hop character, keep it subtle and use only floral or spicy type hops. I prefer German grown Hallertau hops, but other German grown hops, such as Tettnang, Perle or Tradition, work well also. These hops, when grown outside of Germany, can still work well but you should check with your supplier first if you are not sure how closely they match the German grown hops. If you cannot get any of those hops, try to select hops with that same flowery or spicy noble hop character. Some decent substitutions are Liberty and Mt. Hood. You can also try Crystal, Ultra, and Vanguard. The big picture is that you want very low hop character and just a balancing bitterness that complements and integrates with the malt. The balance of bittering versus malt sweetness should be even or slightly on the sweet side. The bitterness to starting gravity ratio (IBU divided by the decimal portion of the specific gravity) ranges from 0.2 to 0.4, but I like to target around 0.3 when looking at the recipe before taking concentration into account. Restrict your late hops to small additions. In general, 0.25 to 0.5 oz (7 to 14 g) in the last 20 to 30 minutes of the boil for a 5-gallon (19 L) batch is the most you should use.

You can ferment eisbock with almost any lager yeast, though my favorites are White Labs WLP830 (German Lager) and Wyeast 2206 (Bavarian Lager). Different lager yeast strains will emphasize different aspects of the beer. Some will emphasize malt character, some will emphasize hop character, and some will be in-between, but all can produce an excellent eisbock with proper fermentation. It is important to note that the sweetness present in eisbock is from a low ratio of hop bitterness to residual malt sweetness, not from incomplete fermentation.

While this style is higher in alcohol than most lagers, the beer should never be hot or solvent-like. A gentle warming when you drink the beer is what you want. Anything more is a flaw. You will run into judges that do not understand this and seem to think eisbock is what they use to fuel jets at the airport. Do not fall into that trap. Instead, make efforts to educate those that think hot alcohols are good to drink. Proper control of fermentation temperature, a proper pitch of healthy yeast, and adequate nutrients is all it takes to avoid that hot alcohol problem.

When making lagers, I like to chill the wort down to 44 °F (7 °C), oxygenate, and then pitch my yeast. I let the beer slowly warm over the first 36 hours to 50 °F (10 °C) and then I hold this temperature for the remainder of fermentation. If fermentation seems sluggish at all after the first 24 hours, I am not afraid to raise the temperature a couple degrees more. The idea is to reduce the diacetyl precursor alpha-acetolactate, which the yeast creates during the early phase of fermentation. Once the growth phase of fermentation is complete, it is important that fermentation be as vigorous as possible. It may never be as robust as fermentation at ale temperatures, but it is important to have enough activity to blow off aromatic sulfurs and other unpleasant compounds. Vigorous yeast activity at the end of fermentation also improves reduction of compounds such as diacetyl. Starting fermentation colder only works well if you are pitching enough clean, healthy yeast at the start. If not, you will need to start warmer (perhaps 55 °F/13 °C) to encourage more yeast growth. Even if you start fermentation warmer, you can still raise the temperature toward the latter part of fermentation.

Since diacetyl reduction is slower at colder temperatures, a cold fermented lager may require a diacetyl rest. To perform a diacetyl rest, simply raise the temperature into the 65 to 68 °F (18 to 20 °C) range for a two-day period near the end of the fermentation. While you can do a diacetyl rest after the fermentation reaches terminal gravity, a good time for a diacetyl rest is when fermentation is 2 to 5 specific gravity points (0.5 to 1 °P) prior to reaching terminal gravity. Brewers ask how they should know when fermentation has reached that stage. My advice is to raise the fermentation temperature for a diacetyl rest as soon as you see fermentation activity significantly slowing. It will not hurt the beer and it should help the yeast reach complete attenuation as well.

It seems that nearly every beer style improves with some period of cold conditioning and this style is no exception. Traditional lager conditioning utilizes a slow temperature reduction before fermentation reaches terminal gravity. The purpose of the slow cooling rate is to avoid sending the yeast into dormancy and to prevent them from excreting a greater amount of compounds that lead to fruity character in the beer. After a few days, the beer reaches a temperature close to 40 °F (4 °C) and the brewer transfers the beer into lagering tanks. If you want to use this technique, you will need precise temperature control so that fermentation slowly continues and the yeast remains active.

Personally, I do not expect lagering to reduce undesirable fermentation compounds. I prefer to hold the beer at warmer temperatures if I expect the yeast to accomplish any change in the beer. The yeast is far more active and able to reduce fermentation byproducts at higher temperatures. Once I am certain the yeast has completed every job needed, I slowly lower the beer temperature and then use a period of cold storage near freezing. This time in storage allows very fine particulates to settle out and the beer flavors to mature. In any case, great lagers take time, so do not rush things.

Once the beer has finished fermentation, let it lager for one month at near-freezing temperatures. Then transfer the beer to a Cornelius keg or similar container that can be flushed with CO2 and can withstand the freezing process without cracking. Put the beer in the freezer, checking every 30 minutes by shaking the container. Once ice crystals form, you will hear them sloshing against the side of the keg. Initially, the sound of the ice crystals will be faint, but as more ice forms, the sound will increase. Pull the beer out of the freezer when the beer sounds slushy. What you are shooting for is the point where approximately 20% of the beer has turned to ice. The first few times you might freeze too much or too little, but experience will eventually let you get the process down pretty close to 20%. Use CO2 pressure to transfer the liquid portion from the keg to another container, leaving behind the ice. You can melt and measure the ice left behind to help determine the strength of the beer post-concentration. If you are lower than intended, you can freeze the beer again. If you are higher, you can always add sterile, distilled, de-aerated water to dilute it.

If you remove anywhere in the general range of 10 to 30% concentration, call it good enough and try to adjust your process next time. I know some brewers who shoot for as much as 50% water removal, but most of those beers I have tasted were heavy, syrupy, alcoholic and not great examples of the style. It is best not to freeze concentrate the beer by more than 25%.

EISBOCK
by the numbers
OG: 1.078–1.120 (18.9–28.1 °P)
FG: 1.020–1.035 (5.1–8.8 °P)
SRM: 18–30
IBU: 25–35
ABV: 9–14%

Steve’s 50 Eisbock

(4 gallons/15 L, all-grain)
OG = 1.090 (21.6 °P)  FG = 1.021 (5.3 °P)
IBU = 27 SRM = 15 ABV = 9.2% (10.6% ABV after concentration)

Ingredients
10.4 lbs. (4.7 kg) Best Malz Pilsen (or similar continental Pilsner) malt 2 °L
7.3 lbs. (3.3 kg) Munich malt (8 °L)
0.9 lb. (400 g) Weyermann CaraMunich® III malt (57 °L)
4.8 AAU Magnum hops (60 min.) (0.4 oz./12 g at 13.5 alpha acids)
1.6 AAU Hallertau hops (30 min.) (0.4 oz./12 g 4.0% alpha acids)
White Labs WLP830 (German Lager) or Wyeast 2206 (Bavarian Lager)

Step by Step
Mill the grains and dough-in targeting a mash of around 1.5 quarts (1.4 L) of water to one pound (0.45 kg) of grain (a liquor-to-grist ratio of about 3:1 by weight) and a temperature of 155 °F (68 °C). Hold the mash at 155 °F (68 °C) until enzymatic conversion is complete. Infuse the mash with near-boiling water while stirring or with a recirculating mash system raise the temperature to mash out at 168 °F (76 °C). Sparge slowly with 170 °F (77 °C) water, collecting wort until the pre-boil kettle volume is around 6.5 gallons (25 L) and the gravity is 1.070 (17 °P).

The total wort boil time is 90 minutes, which helps reduce the S-Methyl methionine (SMM) present in the lightly kilned Pilsner malt and results in less Dimethyl Sulfide (DMS) in the finished beer. Add the first hop addition with 60 minutes remaining in the boil. Add the second hop addition 30 minutes later. Add Irish moss or other kettle finings with 15 minutes left in the boil. Chill the wort to 50 °F (10 °C) and aerate thoroughly. The proper pitch rate is around 600 billion cells, which is six packages of liquid yeast or two packages of liquid yeast in a 10-liter starter. You should consider making a smaller beer first and repitching the yeast from that beer into this one instead of making such a large starter.

Ferment around 50 °F (10 °C) until the yeast drops clear. With healthy yeast, fermentation should be complete in two weeks or less, but do not rush it. Cold fermented lagers take longer to ferment than ales or lagers fermented at warmer temperatures. If desired, perform a diacetyl rest during the last few days of active fermentation.

Once the beer has finished fermentation, let it lager for one month at near-freezing temperatures. Transfer the beer to a Cornelius keg or similar container that can be flushed with CO2 and can withstand the freezing process without cracking. Freeze concentrate the beer by 20%. Transfer the still liquid portion to another container, leaving behind the ice portion. It will be best to force carbonate this beer versus trying to bottle condition it. Target a carbonation level of two volumes. A month or more of cold conditioning at near freezing temperatures will improve the beer. Serve at 43 to 46 °F (6 to 8 °C).

Steve’s 50 Eisbock

(4 gallons/15 L, extract with grains)
OG = 1.090 (21.5 °P)  FG = 1.021 (5.3 °P)
IBU = 27 SRM = 17 ABV = 9.2% (10.6% ABV after concentration)

Ingredients
12.3 lb. (5.6 kg) Munich blend LME (9 °L)
0.9 lb (400 g) Weyermann CaraMunich® III Malt (57 °L)
4.8 AAU Magnum hops (60 min.) (0.4 oz./12 g at 13.5 alpha acids)
1.6 AAU Hallertau hops (30 min.) (0.4 oz./12 g 4.0% alpha acids)
White Labs WLP830 (German Lager) or Wyeast 2206 (Bavarian Lager)

Step by Step
I have used a number of Munich blend extracts and most will do an admirable job of brewing eisbock. Always choose the freshest extract that fits the beer style instead of focusing on the brand name. If you cannot get fresh liquid malt extract, use an appropriate amount of dried malt extract instead.

Place the milled CaraMunich® loosely in a grain bag. Steep the bag in about 1 gallon (~4 liters) of water at roughly 170 °F (77 °C) for about 30 minutes. Lift the grain bag out of the steeping liquid and rinse with warm water. Allow the bags to drip into the kettle. Do not squeeze the bags. Add the malt extract and enough water to make a pre-boil volume of 5.9 gallons (22.3 liters) and a gravity of 1.076 (18.4 °P). Stir thoroughly to help dissolve the extract and bring to a boil.

Once the wort is boiling, add hops at times indicated. Add Irish moss or other kettle finings with 15 minutes left in the boil. Chill the wort to 50 °F (10 °C) and aerate thoroughly. The proper pitch rate is around 600 billion cells, which is six packages of liquid yeast or two packages of liquid yeast in a 10-liter starter. You should consider making a smaller beer first and repitching the yeast from that beer into this one instead of making such a large starter.

Ferment around 50 °F (10 °C) until the yeast drops clear. With healthy yeast, fermentation should be complete in two weeks or less, but do not rush it. Cold fermented lagers take longer to ferment than ales or lagers fermented at warmer temperatures. If desired, perform a diacetyl rest during the last few days of active fermentation.

Once the beer has finished fermentation, let it lager for one month at near-freezing temperatures. Transfer the beer to a Cornelius keg or similar container that can be flushed with CO2 and can withstand the freezing process without cracking. Freeze concentrate the beer by 20%. Transfer the still liquid portion to another container, leaving behind the ice portion. It will be best to force carbonate this beer versus trying to bottle condition it. Target a carbonation level of two volumes. A month or more of cold conditioning at near freezing temperatures will improve the beer. Serve at 43 to 46 °F (6 to 8 °C).

Issue: July-August 2013