Farmhouse Mild (Batch 05): Recipe

This is the fifth iteration of Farmhouse Mild, and presented a good opportunity to try out a new yeast blend, which I always love.  In this case, it was GigaYeast Farmhouse Sour (GB121), which is new enough that it's not even on GigaYeast's website.  Instead, I had to take the description from Farmhouse Brewing Supply's website, which says that this is "a blend of Belgian ale yeast, Brett and lactic acid bacteria-- sweet, sour and a little funky."  This is my first product from them, and it sounds quite promising.  Hopefully the IBU in this one don't interfere too much with the lacto performance.

The other half of this batch is with an evolving blend that I've been using, Ambrosia Blend 05, which is a mixture of Yeast Bay Wallonian Farmhouse, East Coast Yeast Farmhouse Brett (Pure Strain) (ECY03-B), and Ambrosia Blend 002 (East Coast Yeast Saison Blend (ECY08), Brett C., and Brett Trois).

For the grist, I went with my typical mixture of a few different grains, including several adjuncts.  I started fairly late in the day, so ended up using some wheat and rye, foregoing the oats and raw spelt that I've used in the past.  (I want to try a cereal mash the next time I use raw spelt, and I was nearly out of oats.)  For hops, standard 60-minute addition for a bit of bitterness and for flameout, as always, I went with a decent amount of fragrant American hops.  In this case, Simcoe.

The recipe for the full batch is as follows:

Batch Number: 90

Brew Date: July 6, 2014

Bottle/Keg Date:

Batch Size: 10 Gallon

OG: 1.042 (estimated); 1.040 (measured)

FG: 1.003 (estimate); 1.005 (GigaYeast);

Fermentation Temperature: 72*F

IBU: 24

ABV: 5.2% (est.)

SRM: 4.0

Mash: Single infusion for 60 minutes at 152 F.

Boil: 60 minute

Fermentables

10lb 6oz French Pilsner

2lb Wheat, Flaked

1lb Vienna Malt

1lb Rye Malt

1lb White Wheat Malt

12oz Acidulated Malt

Salts & Water

8.0g Calcium Chloride (all added directly to the kettle)

4.0g Gypsum (all added directly to the kettle)

Resulting water profile (based on BrewCipher) is as follows:

Mash pH (est.): 5.42  (measurement swung from 5.4 to 5.5)

Calcium: 94

Magnesium: 12

Sodium: 7

Chloride: 88

Sulfate: 70

I used lactic acid to adjust the pH of the sparge water, adding 5mL to the 8.75 gallons of water used for the sparge.

Hops

1oz Nugget (13.3 AAU), pellet, at 60 minutes

4oz Simcoe (13.0 AAU), pellet, at flameout

Other

2 tsp. Wyeast Yeast Nutrient at 10 minutes

Yeast

5 Gallons: GigaYeast Farmhouse Sour (GB121) (Generation 1)

5 Gallons: Ambrosia Blend 05 (Generation 2)

For the GigaYeast portion, I simply pitched the pack, which was quite fresh (June 25, 2014).

For the Ambrosia Blend 05 portion, I calculated that I needed 85mL of slurry from the Demeter Vert cake.  Roughly 1.8 billion cells/mL based on the calculating from my previous slurry post.  Viability should be near 96% harvesting today according to yeastcalculator.com, so take starting volume of 154 billion cells to get to 148 viable cells.  154/1.8 = 85.

Notes

07.06.2014: Chilled to 70*F and pitched into a water bath that should sit at 70-72*F based on the setting (72*F) and differential (2*F).  Each bucket received 30 seconds of pure oxygen through a stone.

07.07.2014: At 24 hours, water bath is at 74*F, likely because it was over 90*F outside. Temperature should come back down a bit over night back toward 72*F.

07.09.2014: At 2.5 days, beer sitting at 70*F. Controller still set at 72*F with a 2*F differential.

07.27.2014: GigaYeast Farmhouse Sour portion measures 1.005 as final gravity, using the BrewCipher refractometer conversion.  10 Plato originally, and now measuring 3.75 Plato, converting to 1.0047 FG.

Same gravity readings for the Ambrosia Blend 05 portion.

The GigaYeast portion was blended into a new batch of Science & Art #3, with this one consisting of 4.5 gallons of Farmhouse Mild, one gallon of Citrine (dreg portion of Blend 05), and one gallon of Demeter Passion (from 5 bottles)

The Ambrosia Blend 05 portion was put into a keg.  Oddly, tasted normal at the beginning of the day, but after transferring to the keg and sitting for a few hours, I noticed some diacetyl.  That's happened with this one before, and ended up being why I added the lemon guavas to Farmhouse Mild (Lemon Guava), as those gave some additional sugars to get the Brett going again, which allowed it to clean up diacetyl presumably created by pedio that's infected plenty in the brewery (originally introduced through Crooked Stave dregs, which seem to have a pedio strain that really kicks up diacetyl).

If this one ends up showing signs of diacetyl after two weeks on its own in the keg (I intentionally transferred a decent amount of the cake to have Brett in suspension), then I'll consider adding in some fruit, or maybe even bottling and priming with some fruit juice.  It may take a bit of time, but the Brett should be able to clean up pedio's mess.

08.24.2014: For the portion that had some issues with diacetyl, I transferred it back to a carboy on top of the juice from 8 pounds of watermelon.  I also added some fresh yeast from Demeter Automne, hoping to capture enough Brett to clean things up.

11.16.2014: Tasting notes for the watermelon portion can be found here.