Double-Decocted Czech Dark Lager

Double-Decocted Czech Dark Lager

(5 gallons/19 L, all-grain)
OG = 1.052  FG = 1.014
IBU = 30  SRM = 27  ABV = 5%

This beer is in the style of U Fleků, the best-known Czech example of this style, and uses the mash schedule from that brewery. It is a little different from the common schedules that I use. When pulling decoctions, take about 1⁄3 of the thick part of the mash to heat in your decoction kettle. Maintain the main mash at the current rest temperature until the decoction is finished. The recipe uses a slow, traditional lagering schedule.

Ingredients
5.5 lbs. (2.5 kg) Pilsner malt
3.33 lbs. (1.5 kg) Munich malt
1.66 lbs. (750 g) Weyermann CaraMunich® Type 3 malt
8 oz. (227 g) Weyermann Carafa® Special Type 3 malt
3.8 AAU Saaz hops (first wort hop) (1 oz./28 g at 3.8% alpha acids)
3.8 AAU Saaz hops (60 min.) (1 oz./28 g at 3.8% alpha acids)
1 oz. (28 g) Saaz hops (5 min.)
Wyeast 2278 (Czech Pils), White Labs WLP800 (Pilsner Lager), or Mangrove Jack’s M84 (Bohemian Lager) yeast
3⁄4 cup corn sugar (if priming)

Step by Step
This recipe uses reverse osmosis (RO) water. Adjust all brewing water to a pH of 5.5 using phosphoric acid. Add 1 tsp. of calcium chloride to the mash.

This recipe uses a double decoction mash, with some step mashing. Use enough water to have a moderately thin mash (2 qts./lb. or 4.2 L/kg). Mash in the Pilsner and Munich malts at 99 °F (37 °C) and hold for 10 minutes. Raise the mash temperature to 127 °F (53 °C) and hold for 15 minutes. 

Pull the first decoction, resting it at 145 °F (63 °C) for 15 minutes and 163 °F (73 °C) for 15 minutes, before boiling for 15 minutes. Remix the decoction with the main mash. The mash should now be at 145 °F (63 °C). Allow the mash to rest for 15 minutes.

Pull the second decoction, heating and resting it at 163 °F (73 °C) for 15 minutes, before boiling for 15 minutes. Remix the decoction with the main mash. The mash should now be at 163 °F (73 °C). Allow the mash to rest for 15 minutes.

Add the CaraMunich® Type 3 and Carafa® Type 3 malts. Raise the mash temperature to 170 °F (77 °C), and recirculate for 20 minutes.

Sparge slowly and collect 6.5 gallons (24.5 L) of wort. Boil the wort for 90 minutes, adding hops at the times indicated in the recipe. 

Chill the wort to 50 °F (10 °C), pitch the yeast, and ferment until complete (which could take up to two weeks). Rack the beer and lager at 32 °F (0 °C) for 13 weeks.

Rack the beer, prime and bottle condition, or keg and force carbonate to 2.4 v/v.