Brambic – Spontaneously Fermented Wild Homebrew

Against what may or may not be good logic, I’ve begun a new sour beer project. My goal is to successfully create a delicious sour beer fermented only from airborne yeast and bacteria. There is something beautiful about the idea of successfully producing a delicious sour beer that reflects the micro-flora present where I live. I love the tangible connection that can be made with world-renowned Lambic brewers who continue to brew traditional spontaneously fermented beers (as well as American craft brewers like Allagash, Jester King, and Russian River). I am keeping this project as wild as possible; I will not be culturing yeast from fruit, grains, bottle dregs, or any other source, rather only what I can capture across the cool evening breeze.

Brooklyn wild cultures.

Brooklyn wild. What fermentive creatures lurk in our Gowanus air?

The Internet is full of stories both of success and failure when it comes to truly spontaneous beer. Whenever I attempt a technique that includes a high probability for failure, I try to set as many variables in my favor as possible to get a successful end result. There are no guarantees for success in a project like this, but taking a few simple measures can greatly increase your odds. Using this logic, I decided that running multiple samples and testing their qualities before pitching into a full 2.75 gallon batch of beer was the way to go. This was especially important given the fact that I live an dense urban environment with little vegetation and no fruit bearing trees that could be attractive homes for wild yeast.

My Process

_DSC1962Initially I prepared (3) 8 oz. samples of sanitary 1.030 OG wort and placed them boiling hot into pint sized mason jars. I added 0.3 ml of 88% lactic acid to each sample in order to acidify each below pH 4.5. My goal is to inhibit pathogens from growing in the wort as well as non-pathogenic bacteria that can produce objectionable flavors. Since I would be tasting the wort, I wanted to minimize terrible tasting samples as well as ones that could potentially make me sick.

Each of the three samples were placed around my apartment. One was located on the roof of my building, one in front of an open window at the rear of my apartment, and one in front of an open window at the front of my apartment. Each were covered with a couple layers of cheese cloth to prevent any insects from entering the sample and then left to cool for approximately 24-hours. After 24-hours I fitted each jar with a lid and airlock to create an anaerobic environment, providing control of another variable and putting selective pressure on the organisms growing in the wort.

I completed this experiment in the late fall, which according to American Sour Beers offers the best probability for culturing yeast and bacteria that will have a positive fermentation character.

After approximately one-month, I completed a sensory analysis of each sample (smell and taste). In hindsight, I should have also taken pH and gravity measurements.

_DSC2024Sample A – In Front of Window – Small filmy pellicle. Cabbage, some baby diaper. No apparent alcohol flavor.

Sample B – Outside on Roof – Small filmy pellicle. A couple spots of white fluffy mold. Some alcohol on nose. Light rubbery phenol.

Sample C – In Front of Window – Small filmy pellicle. Cabbage. Some oniony aromas. Pretty sweet, low alcohol.

Encouraged by the initial results, I stepped each into a three new 300-ml sanitary starters. Each were allowed to ferment for another month under airlock.

Sample A – Very sweet. Didn’t appear to ferment much. Clean.

Sample B – Quite sour. Some definite plastic-like phenolics and slight alcohol. Some pleasing barnyard notes.

Sample C – Reminiscent of pickle juice. The most sour. Definite alcohol on nose. Not very pleasant.

After the second round of fermentation, I decided that Sample B (the sample pulled from my roof) was the most pleasing (or least offensive). I pitched it into a fresh 1200 ml starter (also under airlock) and made preparation to brew a full 2.75 gallon batch. For my recipe, I decided on a simple golden grain bill to act as a clean slate for the culture to express itself.

2014 Brambic Recipe

_DSC2036Size: 3.25 gal
Efficiency: 75%
Attenuation: 90% (estimated)

Original Gravity: 1.049 SG
Terminal Gravity: 1.005 SG (estimated)
Color: 3.33 SRM
Alcohol: 5.71% ABV (estimated)
Bitterness: 0.0 IBU

4.0 lb (64.6%) Dingemans Belgian Pils
2 lb (32.3%) Briess Flaked Wheat
3 oz (3.0%) Weyermann Acidulated Malt

Mash Regiment:
A turbid mash regiment (basically a thin decoction) was completed through the steps below. A Ferulic acid rest was completed to encourage the formation of 4-vinyl guaicol which Brettanomyces can theoretically convert into 4 ethyl-guiacol which produces some of the ‘funky’ aromas and flavors that Brettanomyces is known for. A short Beta rest was followed by a very high Alpha rest to encourage a dextrinous wort and protracted secondary Brettanomyces fermentation.

113 °F – Ferulic Acid Rest – 10min
136 °F – Protein Rest – 5min
150 °F – Beta Rest – 20min
162 °F – Alpha Rest – 30min
168 °F – Mashout Rest – 5min

Water Treatment:
Extremely Soft NYC Water
4g Gypsum (to mash)
4g Calcium Chloride (to mash)

1.25 oz AGED Cascade (0% AA) – 90 m

Kettle Additions:
0.5 ea Whirlfloc Tablets (Irish moss) –  15 m
0.5 tsp Wyeast Nutrient – 10 m

1200ml Brambic Spontaneous Culture
Fermented at ambient temperatures (70°F or so)

The beer will be allowed to ferment for at least a year until packaging.

6 thoughts on “Brambic – Spontaneously Fermented Wild Homebrew

  1. Many thanks for this article. I am very interested by this technik and want to test it at home.
    Are you sure it is mandatory to add lactic acid ? Or maybe I can add something more natural ? My idea is really to do a pure homemade beer.

    Did you retaste it after a couple of month or not yet ?

    • Yes, I would definitely pre-acidify the wort. Since my intent was to taste the various samples, acidifying the wort gave me some confidence that I wouldn’t be tasting anything that could make me sick.

      I’ve tasted the beer a year in and it is still … not great. It’s an experiment where I am mainly sitting and waiting on it. My anticipation (based on the experience of people like Allagash) is that the cultures can take anywhere from a year to several to get something tasty.

      • Interesting, thanks for your experimentation.
        When you tasted it, did you try to mesure the specific gravity ?
        Are the cultures slower than the one that we put artificially in the beer ? And what if you try to do a “Gueuze” by re-doing a fermentation in a bottle ?
        Anyway, even if your first test is not tasty it makes me confident that it is working even if we can read everywhere (in french sites at least) that this kind of beer can be done only in Belgium.

        • Yes, when I tasted it I also checked pH and SG. The attenuation isn’t quite where I wanted it to be — 1.026, but it is my hope that it will drop further. Depending on what you get in your culture, your attenuation and the speed at which it ferments will certainly vary.

          While I’m not sure that this will turn out for me, I am confident based on what pro-brewers here have done that it is possible. While it may be different than what is produced in Belgium, there is no reason that success can’t be achieved at any local; it may be different, but I bet tasty beer is possible.

    • Hi Robbie,

      Unfortunately, the beer winded up with somewhat of a DMS problem. I ended up dumping without packaging. I have however continued to prop the cultures, and have used with great success — particularly when co-pitching with outher mixed cultures that I have in my library.



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