Part III - Our mixed culture fermentation
We refer to our fermentation culture as mixed, because unlike many beers which are brewed with one single strain of yeast (Wyeast American Ale Yeast 1056 or White Labs Dry English Ale 007 to name a couple) our culture is made up of hundreds of different strains of yeast and bacteria. Some are cultivated originally from the commercial propagators and others are from native plants. It includes native cultures built up from Yarrow that was harvested in the Yakima wine region and Elderflowers from the Bastyr Campus and other wild cultures gathered near the Ballard Locks. We’ve been working with some iteration of this culture for three years now. We don’t dump the culture and start over with a new commercial batch, instead we pitch from a combination of our starter and the previous batch. It took a while before our culture hit it’s stride, but now on it’s several hundredth generation, it’s singing wonders.
I thought about including how I propagated the culture, but since others have written some great articles on how to cultivate your own mixed culture, I’ll just point you toward Garrett Crowell formerly of Jester King and Michael Tonsmeire of the Mad Fermentationist.
In addition to creating beers made with a sense of place, we believe mixed culture fermentation creates greater depth to our beers. Farmhouse beers are yeast driven, meaning the dominate flavor notes of our beers are created by our yeast culture. Instead of working with one musical instrument - a single strain of yeast - to create the sound we want, we have a whole symphony - creating a harmonious musical composition with a depth unachievable with one instrument.
We’ve learned how to nudge it in different directions depending on what flavor profile we want to achieve. We like to think of ourselves as shepherds rather than controllers - giving those cultures the time they need to make great beer. We’ve created a unique flavor profile that simply cannot be replicated elsewhere.
Lastly, our beers are still alive. All of our beers will be unpasteurized and bottle conditioned. Meaning, upon bottling or kegging, we don’t filter the beer or flash pasteurize it to remove the suspended and active yeast. Instead, we add additional priming sugar and allow a second fermentation to happen in the final vessel. The existing yeast, consumes the sugar, releasing CO2 and carbonating the bottle naturally. This last fermentation period is the icing on the cake. It also means that as our beer ages in the bottle, it changes. We’ve cellared beers as long as three years in the bottle. Some reach their prime at eight weeks in the bottle, others a year, but all of them continually evolve - adding to the complexity and enjoyment of drinking these beers.
- Andrew Pogue | Co-Founder of Fair Isle Brewing