Building A Brewery, Chapter 4: For the Love of Microbes


Photo via Oakhold’s Facebook page: “The ‘brewery’ part of our Farmhouse Brewery is slowly but surely making progress.”

Editor’s Note: This is the fourth in a series of journal entries in which Oakhold Farmhouse Brewery founders Levi Loesch and Caleb Levar write about the trials and tribulations of starting their mixed-fermentation brewery in Northern Minnesota. Catch up with Chapter 1: Oakhold Digs In, Chapter 2: The Right Tools For The Job, and Chapter 3: On Outside Expertise.

About a year into my Microbiology PhD work at the University of Minnesota, I began falling out of love with academia and began thinking about other applications of microbiology. This was right around the time my preliminary examination was fast approaching, but I’m sure the stress and self-doubt associated with that had nothing to do with it.

I had been homebrewing for a few years and had begun to work with mixed-cultures, focusing on combinations of Saccharomyces and Brettanomyces. Dabbling in the microbiology of beer reminded me what I love about the wonderful world of microbes and why I had chosen this profession. A bad day at the bench could be easily remedied by streaking out a culture for isolation, performing a Gram’s stain, or getting lost in the microscope.

By the end of 2011 I had collected more pure isolates and mixed-cultures than I knew what to do with. In order to save these cultures for future use, I stored many of them as glycerol protected stocks at -80°C. Some of these were commercially available, but more often I used unique beers to isolate interesting microbes that were new to me. These strains provided a glimpse into the microbial diversity present in many of our favorite beers, but Levi and I kept returning to a few mixed-cultures for use in our beers. The microbial mixes we now utilize in barrel fermented beers each have their own unique characteristics, giving us the ability to blend several different profiles into a single finished product.

Love of microbiology will be a defining feature of Oakhold Farmhouse Brewery. While we use the same core set of ingredients as all other breweries, our interest in the microbiology of mixed culture fermentation allows us to explore territory that is often overshadowed by some styles in the craft beer boom that we are currently experiencing. Instead of making yet another IPA and fighting for space on increasingly crowded shelves, we aim to stand out by exploring the complex interactions between raw materials and the microbes we use in our brewery.

Developing beer recipes

Many recipes begin with an idea of a finished product, and tweaks to the recipe over time are used to drive characteristics of the beer toward that vision. Perhaps some additional bittering hops are added, or water chemistry is adjusted, or the malt bill is altered somewhat. Recipe development at Oakhold isn’t much different, but the organisms used for fermentation are considered a key component of the recipe that can be altered.

In the case of The Vitalist, a rye saison, the grain bill has remained largely unchanged since I first brewed it in early 2012. But whereas that first brew incorporated only Saccharomyces and Brettanomyces, the culture used for this beer now contains lactic acid–producing bacteria. We saw this change as the natural evolution of the beer, as the culture we now use for this beer resulted from our first wine barrel aged treatment of the beer.

Wine barrels are not a sterile environment and the organisms present in the wine can persist to proliferate once a proper environment is once again provided. In the case of this beer, the lactic acid produced by the bacteria in the barrel added depth in the form of a tart and fruity character that complemented the oak and Brettanomyces. We saved the culture by freezing it at -80°C, and though the ratio of the microbes does change upon thawing and propagating, supplementing the mixed culture with pure cultures of Saccharomyces and Brettanomyces allows us to achieve a consistent fermentation and flavor profile in this beer.

Related Post — How yeast works: A layperson’s guide to saccharomyces

Another way to diversify our beer is by using fruit, herbs, or hops in the finished beer. As homebrewers, we had ample opportunity to get creative with re-fermentations and aging since a full wine barrel yielded more beer than we wanted to consume as a singular iteration. We would often split portions of the finished beer into carboys, add hops, fruit, or other fermentables, and a few months later we could assess the flavor and decide what we enjoyed the most. Over the years we have learned which hop varieties do well as dry hops in barrel-aged sours, what fruits (and in what forms) are best for aging, and which flavor combinations we would like to see pop up as special beers Oakhold brings to festivals in the future.

One example of a great addition has been hibiscus. In mid-2011, a good friend and mentor in the lab where I worked scheduled her thesis defense and, as the resident homebrewer, I was on the hook for producing a celebratory beer. Because this friend collected pink lab ware, I decided to brew a pink beer using a hibiscus tea for the pink color. Fermented with saison yeast and low in alcohol, it was a hit and resulted in a number of other pink beers at various lab functions over the years. Of the handful of hibiscus-infused beers we brewed, perhaps the most memorable was a version of The Vitalist aged with rose hips and dried hibiscus petals, inspired by Jolly Pumpkin’s iO Saison.

FairState_Roselle_KDK_11.14.16 (5 of 11)

Fair State Roselle // Photo by Kevin Kramer, The Growler

In late November 2014, Niko Tonks of Fair State Brewing asked Levi and me if we had other ideas for mixed-culture barrel-aged beers. We pitched hibiscus as one possible idea, and though the beer that we had envisioned wasn’t produced, hibiscus found its way into the second of the Lactobac Series beers, known now as Roselle. Though Roselle has taken on a life of its own and really isn’t recognizable as stemming from a few small batches of homebrew, this experience has provided a number of good lessons.

First, ideas and the resulting recipes may change, but common threads keep coming back and will eventually find their way into something great. Second, a dogmatic adherence to the beers a brewery opens with isn’t healthy (or profitable). When Lactobac 2 was first produced we all expected a fun, one-off beer. But the reception was overwhelming and Roselle is now one of the year-round (and canned!) offerings at Fair State. So while we are excited about the beers we currently have planned for Oakhold, we are sure that recipes will be tweaked, modified, or cast aside for new ideas when the consumer is ready for something new or shows sudden enthusiasm for a trial batch.

Next page: Building terroir

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