Chestnut Beer

(10 gallons/38 L, all-nut)
OG = 1.067  FG = 1.012
IBU = 30  SRM = 7  ABV = 7.2% 

Ingredients

25 lbs. (11.3 kg) dehydrated chestnuts (crushed)
2 lbs. (0.9 kg) rice hulls
4 fl oz. (120 mL) 88% lactic acid
4 fl oz. (120 mL) Termamyl
2 fl oz. (60 mL) SEBAmyl
12.5 AAU East Kent Golding hops (60 min.) (2.5 oz./71 g at 5% alpha acids)
8 AAU Strisselspalt hops (15 min.) (2 oz./57 g at 4% alpha acids)
2 oz. (57 g) Strisselspalt hops (0 min.)
2 oz. (57 g) Fermaid O
0.25 oz. (7 g) diammonium phosphate (DAP)
6 packs Wyeast 1762 (Belgian Abbey Style Ale II) (or build up an equivalent size yeast starter)
Coopers Carbonation Drops 

Step by step

Crush the dehydrated chestnuts into a fine powder and then add chestnut flour and rice hulls directly to the mash tun (I chose to smoke and roast a small percent of the flour for added dimension, which is optional). Alternatively, you can buy chestnut flour if you trust the source. Add 10 gallons (38 L) of strike water at 175 °F (79 °C) to get mash to ~165 °F (74 °C). Dilute 88% lactic acid to three times as much water and add 2 Tbsp. every 10 minutes until the mash reaches 5.5–5.75 pH when measured at room temperature.

Add Termamyl at the start of the mash and hold for 30 minutes. Reduce temperature to 145 °F
(63 °C) and continue to add 2 Tbsp. of the lactic acid solution every 10 minutes until the mash reaches 5.2–5.4 pH. Then add SEBAmyl and hold for 75 minutes for the saccharification rest. Both of these enzymes can be purchased in homebrew-size quantities from glutenfreehomebrewing.com.

Lauter and sparge at 168 °F (76 °C) until there’s 12.5 gallons (47 L) of wort in the kettle. 

Boil wort for 90 minutes, adding hops as indicated. At the end of the boil, chill to 64 °F (18 °C) and transfer to the fermenter. Add 1 oz. (28 g) Fermaid O, 0.25 oz. (7 g) DAP, and the yeast. I used six individual packs of liquid yeast instead of building up a starter because I wasn’t sure how a starter made with chestnut flour would react and I did not want any fermentable beyond chestnut in the beer . . . though if you are OK using malt extract it would be a big money saver. After 24 hours, add another ounce (28 g) of Fermaid O to the fermenter. Fermentation will take 3–4 weeks to complete. 

Once done, transfer to a rye whiskey barrel for 6 weeks, if possible, or add oak cubes previously soaked in rye whiskey. Transfer to bottles, adding one Coopers Carbonation Drop to each bottle or keg and force carbonate as usual.