Sour Blonde 9.1.1 - Spontaneously Fermented

I have been brewing Sour Blonde beer semi-inspired by Belgian Lambic for the last 9 years or so.  This is my latest iteration on the project.  I will be doing a spontaneous fermentation for this batch which involves letting the beer be inoculated by whatever organisms are naturally floating in the air.  This is a practice used by the Belgian Lambic producers and has a long history of producing beers with a strong and complex flavor profile.  I have used this practice once before (Sour Blonde 5.1.1) with mixed results.

These beers are made during cool weather which has been found to be important to limiting the amount of spoilage microbes get into the beer.  They also leverage fairly high hopping rates with aged hops to limit the impacts lactobacillus can have on the beer (as this is hindered by hops and would create acidity too quickly which would hinder the effects of the other microbes) but also not impart high levels of bitterness.  I have waited until December to make the beer to wait for a cold period (although I've chosen an unseasonably warm and damp day for brewing - low 60s and foggy) and have used 3 oz of aged hops for the beer.  My previous attempt at spontaneous fermentation used a small amount of high Alpha Acid hops which I had thought were sufficiently aged but ended up adding quite a bit of bitterness that is only now fading (beer was made in 2017)

The beer is leveraging a small cereal mash with raw wheat in addition to some additional flaked wheat to be used in the main mash.  These beers traditionally use wheat and feature a wort rich in unconverted starches which allow for nutrients to remain in the wort after the simple sugars have been consumed by the wild yeasts and bacteria active early in the fermentation

This was intended to be a 10 gal batch but my efficiency was better than expected so it's going to be more like a 12 gal batch.  I'm shooting for a 1.045 gravity in anticipation of high attenuation which would give me about 5% ABV.  My other beers are a bit higher alcohol so a lower alcohol beer like this could make a valuable blending ingredient.

Anyhow, I plan to blend up some new Lambic style beers here in the next month or so and intent to empty one fermenter in the process which I'll use for this beer and then I'll use the other half to top up the others and add some fresher yeast and nutrients to the mix.

Recipe Details:

• Grain:
• 10 lb Pilsner
• 4 lb Flaked Wheat
• 1 lb Munich
• 4 oz Acid Malt
• Cereal Mash:
• 4 lb raw wheat
• 1 lb Pilsner
• Hops:
• 3 oz of Homegrown Aged Cascade at 60 min
• Yeast:
• Spontaneous Fermentation
• Water:
• 13 gal spring water
• 1 tsp CaCl
• 1 tsp Gypsum

Process Details:

• Batch Size:
• 11 gal (Target 10 gal)
• Mash:
• 150 F for 60 min
• Boil:
• 60 min
• Fermentation Temperature:
• Ambient Basement Temperature
• Primary Duration:
• 1 month
• Secondary Duration:
• 1-3 years

Results:

• OG:
• 1.047 (Target 1.045)
• Efficiency:
• 78% (Target 69%)
• FG:
• TBD (Target 1.04)
• Apparent Attenuation:
• TBD (Target 91%)
• ABV:
• TBD (Target 5.38%)

Brewing Notes:

• 12/2/23 - Did an appreciated cereal mash on the stove top by slowly ramping the mash up to a light boil over the course of a couple hrs.  Then left it sitting over night to cool down
• 12/3/23 - Brewday - 12:00 PM to 4:00 PM- including setup and cleanup
• Heated 10 gal of spring water up to 175 F
• Heated the cereal mash back up to near boiling
• Milled my grain.  Added CaCl and Gypsum to it at this point so I wouldn't forget

• Added 6 gal to the Mash Tun and cycled through the RIMS until the temperature had settled to 160 F
•   Added grain to the mash and stirred well to eliminate dough balls.  Added the cereal mash
• Let the mash sit for 10 min to settle
• Cycled the mash at 152 F for 50 min min
• Heated 8 gal of spring water up to 180 F for sparge
• Drained the mash into the boil kettle doing a manual fly sparge until I'd collected 12 gal
• Started heating the kettle after collecting about 3 gal.  Had it at a boil about 10 min after then end of the sparge
• Added the bittering hops as soon as the hot break subsided a bit

• Boiled for 60 min (boiled off 2 gal as expected)
• At the very end of the boil I removed the hops and transported the 10 gal of boiling wort to my raspberry beds  to cool.  I spilled a quart or two during this move.  I'm going to leave the beer out overnight to cool.
• Measured the gravity of the beer at 1.060.  I really want it to be at 1.045 so I'm going to have to add some water (will figure out how much tomorrow)

• 12/4/23
• Carried the boil kettle into the garage (didn't spill any on this trip)
• Transferred the contents into 2 fermenters.  Got 8 gal

• The kettle loses some water cooling like this with the time to steam so the gravity is now at 1.064.  So, I got about 78% efficiency on this batch
• Added 3 gal of spring water to get to 1.047 which is close enough to my target.  This is 11 gal of wort.
• Setup the fermenters with mostly covered lids in my sour beer room which, I assume, is full of microbes that might aid in this process

• 12/8/23 - There is a bit of foam forming on the beer this morning which is a good sign of initial fermentation

• 12/11/23 - The beer has a fruity aroma and the foam hasn't really progressed very much
• 12/14/23 - Growing some mold and a bit of a pellicle.  I've scooped out the mold.  It has some aroma that I'm familiar with from past beers so I'm not that concerned.  Tasted a bit and it is still pretty sweet

• 12/25/23 - Not much change to the beers.  Still growing this yellow slimy mold.  They still smell pretty good so I'm going to let it continue.

• 12/29/23 - One of them is forming some foam which I'm hoping is a sign of some active fermentation

• 2/25/24 - Transferred Fermenter #2 into fermenter #1 (which were each about half full.  Transferred 6 gal of this batch into fermenter 2 which had the yeast cake in it still