After the success of the step mash I used on my last brew (Vienna Lager), I decided to really go for it and do a double decoction this week. Brewing a Munich Dunkel, I wanted a very malty brew, with a rich creamy head and a full body, on the sweet side. Decoction mashing is probably the pinnacle of difficulty in the brewhouse, and the most time-consuming. Depending on how many steps you are willing to take, this brew could add an hour or two to your brew day. I opted for a double-decoction, the compromise between a single step and a complicated triple process.
A double decoction involves a low temperature protein rest, then removing and boiling a portion of the mash which, when put back in, raises the whole mash to saccharification temperature; after a rest, another portion of the mash is pulled out, boiled, and returned, raising the mash to the point of dextrinization and stopping the enzymes. Or so I am told. I just follow directions!
Dunkel (“dark”) is one of the two main year-round styles of beer in Bavaria, the other being Hell (“light”). Both styles emphasize malt over hops, although a noble hop bitterness and some aroma are appropriate. The lager yeasts used in Bavaria generally ferment clean, leaving no real yeast profile, although many do produce a lot of sulfur during the initial stages of fermentation. I poured the Dunkel’s wort directly into the fermenter from which I had just racked the Vienna, thus using in effect a very large active slurry.
Double D Dunkel
5 gallons, all grain
- 5 lbs. Weyermann Bohemian Pilsner malt
- 3 lbs. dark Munich malt
- 1/2 lb. brown malt
- 1/2 lb. dark (145°L) crystal malt
- 1/4 lb. melanoidin malt
- 1 oz. black malt
- 1 oz. chocolate malt
- 1-1/2 oz. Styrian Goldings hop pellets (@4.5% aa)
- 1/2 oz. Hallertau hop pellets (@3% aa)
- White Labs Old Bavarian Lager yeast (WLP920)
- 3/4 cup corn sugar (for priming)
Crush grains. Heat 14 quarts water to 125°F. Mash in and hold 5 minutes at 115°F. Remove about 1/3 of the mash (6 quarts) and heat to 150°F (leave rest of mash in mash tun at 115°F). Hold kettle 20 minutes, then heat gradually to 200°F. Continue heating quickly to boiling, boil 15 minutes.
Add kettle contents back to main mash, mix in well. Mash temperature should be around 150°F. Hold 20 minutes.
Remove around 2/5 of the mash (7 quarts), heat to 150°F slowly, then quickly bring up to boiling. Boil 15 minutes. Meanwhile, heat 15 quarts water to 170° ( for sparging). Return the kettle contents to main mash, mix in well. Mash temperature should be about 165°F. Hold 10 minutes, then begin runoff and sparge, collecting 24 quarts of sweet wort.
Bring to a boil, add 1 oz. Styrian Goldings pellets, boil 45 minutes. Add 1/2 oz. Styrian Goldings, boil 15 minutes. Add 1/2 Hallertau pellets, boil 15 minutes and remove from heat. Chill to 80°F, take a hydrometer reading, and pour into a sanitized fermenter, splashing well to aerate.
Pitch yeast, seal and ferment warm (60 – 62°F) for three to four days, then move to a cooler spot (52 – 55°F) for four to six days. Rack to secondary, condition cold (35 – 38°F) for three to four weeks. Prime with corn sugar, bottle, age warm for three days then move to cold storage for four to six weeks.
Notes on process: This was the first time I can remember where I had to wait for the mash water to COOL down – I left the kettle on the woodstove overnight, thinking I would get a head start. In fact, the water was at 150° and it took half an hour to cool to 125°F.