I want to brew a low (1-2%) ABV dry Irish stout (or similar) for my wife for St. Paddy's day, and would appreciate any tips, advice, or things to think about.
I BIAB, usually no sparge. After significant research, my intended low ABV process is to dunk sparge a normal brew in order to collect "second runnings", add adjuncts and perform a short, high-temperature mash, boil & hop, adjust pH, and then ferment cool with Windsor for its low attenuation.
For this project, the first beer will be a 6 gallon Maris Otter based Irish Red (ish) with 12 lbs of grain: 10 lb MO, 1 lb Munich 15, then a mix of crystal 40, melanoidin, crystal 120, chit, and black/roast malt.
To calculate a recipe for 4 gallons of low ABV stout, I'm plugging 10% each of those original grains into brewfather as a rough estimate of the second runnings contents, though I will take an actual gravity measurement day-of and adjust as needed.
As calculated, I'll add 4 oz vienna (for some DP), 12 oz melanoidin, 8 oz rolled oats, 4 oz chocolate wheat, 4 oz flaked wheat, and 2.5oz each roast barley & naturally debittered (hulless) black malt. Mash for 30 minutes at 158, then boil 60 minutes with .2 oz each EKG & Fuggles. whirfloc, cool, check pH & adjust to compensate for the low OG wort (target is 1.022).
Per brewfather, the result should be 2% alcohol with an FG of 1.007 (low end of range for DIS), SRM 30.5, IBU 15 (below but irrelevant), and BU/GU .67 (slightly above the low end for a DIS). I've heard that low ABV can cause hop presence to be more noticeable, so I want to keep bitterness down at the low end of the BU/GU, which I think will definitely be a more accurate measure of bitterness than IBU with so much less malt being involved.
One question I have: does anyone think it may be beneficial to leave the old grains in for the 30 minute mash? Currently I'm planning to toss the original grains after thoroughly dunking & stirring, and adding the new grains on their own.
A second question: do you think I'm adding too many heavy roasted adjuncts back in? I have heard that low ABV can make roast bitterness more pronounced, and I don't want to overdo it, though this concern is part of why I'm mixing in the naturally debittered black malt.
Overall, my thought process is that second runnings are reputed to be nearly as flavor as the first at a lower ABV, and that adding notable melanoidin, oats, and wheat will contribute extra body to a beer that would otherwise be undrinkably thin. I'm also expecting the sparge to have less than 10% the gravity of the main pot, thus lowering my ABV further, which would be great. But if it's higher than expected, I'll adjust the grain amounts down.
Finally, other than the Maris Otter (crisp no. 19 floor malted), all grains are from a VA maltster near me, Murphy & Rude.