Acorn Oud Bruin

(5.5 gallons/21 L, all-grain)
OG = 1.046 FG = 1.010 IBU = ~2 SRM = 18 ABV = 4.7%

Ingredients

6 lbs. (2.7 kg) Briess Pilsen malt
2.5 lbs. (1.1 kg) Weyermann Munich I malt (6 °L)
1.5 lbs. (0.7 kg) flaked rye
0.5 lb. (0.23 kg) Dingemans Special B malt
0.25 lb. (113 g) Weyermann Carafa® Special II malt
0.625 oz. (18 g) Willamette hops (aged) (60 min.)
1⁄2 Whirlfloc tablet (50 min.) East Coast Yeast ECY23 (Oud Brune) yeast
2 cups (0.46 L) fermented acorns
3⁄4 cup corn sugar (if priming)

Step by Step

Begin the acorn fermentation process about 1 year prior to brew day. Dry out acorns for one week on baking sheets or other suitable surface. Place the acorns that are free of defections into ball jars and cover, burping the ball jar(s) every week or so. Store in a cool, dark place for 8-12 months. Heat 5-gallons (19-L) water to target mash temperature of 157 °F (69 °C) for 30 minutes. Run off into kettle. Sparge to collect 7.5 gallons (28.4 L) of wort. Boil for 90 minutes, adding hops and Whirlfloc as noted. Chill to 66 °F (19 °C). Aerate the wort and pitch the suggested blend, or a blend of English ale and Lactobacillus of your choice. Allow the fermentation to warm to 68 °F (20 °C) until fermentation appears complete. Place the fermented acorns on a piece of aluminum foil and tap each with a hammer to split. Add acorns including shells to the fermenter either loose or bagged and weighted. Leave at the same temperature, tasting weekly until the desired flavor is achieved. Either keg or bottle the beer to achieve 2.3 volumes of CO₂.