the craft of cultivation, Superior-style
I have a science degree. I am a smart individual. I even took advanced biology and microbiology in college.
Still, when I first learned about cultivating wild yeast, my mind was blown.
It may come as no surprise to many of you that plucking wild yeast out of thin air is not all that difficult. These single-celled organisms are everywhere, on the surfaces we come into contact with every day, in the air we breathe. Convincing the tiny creatures to do our bidding is only a matter of coaxing them to divide predictably into a usable amount.
Think about this. Have you ever read directions on how to make yogurt? Every recipe I have ever come across lists one mandatory ingredient – other yogurt. Commercial yogurt, with live and active cultures, is cited as the key to making more yogurt. The longer I think about it, the more absurd this idea becomes.
Just as the wheel wasn’t used in inventing a wheel, our gastronomically-inclined ancient ancestors didn’t have prepared yogurt on hand when the first batch of yogurt was made. It fermented spontaneously due to the unchecked growth of microorganisms doing their thing. Likely an accident, the way popular lore dictates that beer was probably developed, and even the way in which Penicillin fortuitously came into being.
Prior to the dawn of more modern brewing techniques, fermentation would start spontaneously from wild yeasts on grain or in the air. Over the centuries, many cultures took to preserving yeast in different forms; people began to save, or even exchange, the sediment at the bottom of the vessel to start future batches. Fascinating accounts exist of not only keeping wet and dried yeast in jars, but also on straw, linen, or even wooden stirring vessels placed directly into the wort.
Spontaneous fermentation refers to the process of letting natural bacteria already present on grapes, grains – or in the case of yogurt, milk – initiate the fermentation process. No extraneous addition is needed for this process to happen, simply the proper environment.
If the proper environment for cultivating yeast is in a vineyard in Napa, imagine my surprise in reading a recent article about yeast being coaxed out of the sandy shores of Lake Superior, in Keweenaw, Michigan. Microbiologist Emily Geiger is harnessing the power of spontaneous fermentation, selecting for specific yeast strains, and selling these cultures to breweries, all of whom cannot seem to get enough.
How does Geiger know which to continue developing and which to market? She brews a batch of beer with a particular strain and notes its characteristics.
I cannot help but think of our own local yeast hero. (Can I call Superior “local”? I say yes.) Allyson Rolph, of Wisconsin’s Thirsty Pagan Brewing. In fact, she was the person who initially set my head spinning about wild yeast collection. It was a few years ago, at the Gitchee Gumee Brew Fest when Rolph explained her yeast collection process, which is not unlike that of Emily Geiger.
Barrels, growlers, and firkins are inoculated with various strains that Rolph has collected. As you can imagine, some batches are incredibly successful and others are less so. It’s a complex process with more variables that even I can imagine (and I’ve traveled to Funkytown, Rolph’s nickname for her damp, subterranean barrel room). Yeast is present, but so is bacteria, plus remnants of what was previously in the wood, added with the wood itself, its accompanying microflora, and when all these factors are added together, taking time and temperature into account, it is remarkable that the pieces ever fall into place, really.
Showcasing wild-caught yeast strains was a major part of this event. In addition, other complex techniques like kettle souring, barrel-aging, and the addition of Brettanomyces and Lactobacillus added depth and complexity to the offerings.
Several beers also had fruit-added variations, including my favorite, Hartford Puppy with cherries. The fruit added a tart and earthy presence in the back of the mouth, and the entire sipping process led to layer upon layer of funky flavor, all with a beautiful finish.
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