Counter Culture: When Yeast Gives Rise to More Than Bread


By Maren Tarro

— The relationship between humans and microorganisms is a complicated one often containing all the elements of a Lifetime made-for-TV screenplay: Love, hate, fascination, fear, acceptance, cooperation, exploitation and, of course, murder. This entire spectrum can be viewed in a single commercial break which might include Jamie Lee Curtis singing the bowel-boosting praises of probiotics, the Most Interesting Man in the World admitting even he partakes in the occasional bubbly brew, and then Clorox sharing its diabolical version of white power complete with plans to eliminate entire classes of microorganisms. Oh, the drama!

The Burden of Our Ancestors
During one such string of ads I began to contemplate the inherent dichotomy in our relationship with this seemingly infinite population of organisms. Treated as a single group, our willing association with microorganisms appears similar to risky sexual behaviors with exclamations of ecstasy over raw milk cheeses sounding not unlike the excitement of climax sans condom. (Not surprising when you consider the sensory—physical and emotional—involvement eating comprises: “It just tastes better” is closely tied to “it just feels better.”) But a closer look reveals that while microorganisms can pose many dangers to us, the risks we take when inviting fungi and bacteria into our homes and bodies are calculated risks, with the greatest burden taken on by those who came thousands of years before us.

It’s unknown when exactly humans began to intentionally incorporate the use of microorganisms into their lives. (I say intentionally because we’ve always relied on a variety of flora for many purposes, including digestive and immune support.) It’s possible to imagine yeast was a likely early riser as bread dates back at least 30,000 years. Granted, those first breads were unleavened loaves equivalent to today’s pitas and tortillas, but yeasts were present on the grains used in these early breads. It’s not difficult to suppose that a bit of leftover dough, overlooked or saved for another meal in its clay pot by an ancient baker, would have been thrown in the fire when rediscovered the next day. The slightly risen perhaps noticeably tangy result may have lead the baker to experiment further by allowing the ground grain and water mixture to sit for longer time periods, inadvertently gifting the world with sourdough.

The mechanisms of this happy accident and similar others remained a mystery until the 1800’s when Louis Pasteur and his contemporaries began to understand the role microorganisms play in our lives, both positive and negative. For thousands of years before microscopes, humans were relying on some microorganisms to create and preserve food while being at the mercy of others that infected their food and bodies. One grain fungus a friend, another a foe—and the same with bacteria. The whole while our ancestors were looking toward the heavens for a few higher, larger entities doling out life and death,  those unseen beings were actually among them and in numbers greater than they could imagine. Perhaps the one thing our late relatives were onto was the disputes and battles waged among those imperceptible presences, and the alliances they formed with each other and us.

Fuzzy Failure
At this point I decided to compliment my musings with a tangible prop and so headed to the kitchen to do what sourdough aficionados round the world do: grow wild yeast. Of course, if one wants to observe yeast in action those little packets procured from the supermarket will certainly do, but I was looking for something more experiential and rooted in the past, something less convenient and predictable. I wanted the joy and triumph found in the success of ignorance and luck.

Into a clean jar I mixed equal amounts flour and water, covered it with a dish towel, and set it in a warm spot on the counter. The next day the mixture was slightly bubbly when I removed the towel to “feed” it. I began to feel the stirrings of triumph—until the next day. In only 24 hours my culture had gone from sure thing to fuzzy black failure. After a few minutes contemplating the moldy mess I began to see the setback in a positive light. After all, if coaxing wild yeast from a little flour and water was a certainty, then leavened bread would have graced civilization much earlier. I even felt a sort of kinship with those ancient dough slingers.

After scrupulously cleaning the jar to rid it of spores and other lurking trespassers, I started over, again with equal parts flour and water, with much better results—until the fourth day when the black mold reappeared.
It occurred to me that waiting for my own happy accident might not be the best approach. Surely ancient humans didn’t solely rely on things just happening, however magical they may have considered those happenings. In fact, we have proof they valued and collected knowledge, first through orally passing down information, then pictographs (which in Egypt depict the earliest evidence of bakers maintaining sourdough starters) and, eventually, through written words. Instead of grabbing a torch and scouring pyramid walls for clues or a recipe, I visited our modern version of collective wisdom: Google. And there I discovered a trove of science, myth and even a bit of supernatural belief, the perusing of which felt a little like deciphering the hallowed walls of Giza.

It turns out one does not simply grow yeast. Like a gardener preparing his plot by ridding it of weeds and invaders, so, too, must specific circumstances occur for yeast to flourish. I wasn’t trying to grow yeast; I was trying to create an environment with all the necessary conditions for yeast to grow. I had provided food in the form of flour, hydration with water and the correct temperature to encourage them to reproduce with abandon, but yeast aren’t the only fans of warm, wet dens with ample eats. All manner of fungi and bacteria are happy to take up residence in these conditions.

Yeast, for sourdough Candida milleri, prefers a slightly acidic environment which is intolerable to other microorganisms. To achieve this we need a little help from their friend Lactobacillus sanfranciscensis. This lactic-acid producing bacterium not only lowers the pH to a yeast-friendly level, eliminating competition from other microbes, but in the process breaks sugars down into glucose, a favorite food for yeast. This symbiotic relationship between a yeast and a bacterium results not only in happy microbes but also in a tangy, leavened bread that resists mold and is loved in its many forms by many cultures.

The Sourdough Lifeline
This is where I stopped rolling my eyes at ancient humans attributing natural, scientifically explainable occurrences to gods and magic. Here is where I began to grasp the place bread (and wine and cheese) holds in our history and in our lives still today. For all these things to come together without the aid of understanding microbiology and to be recognized as good and useful is a kind of magic, a gift or bestowal that helped humans stumble forward toward a more sophisticated civilization. We continue to produce sourdough when commercial fast-acting yeasts not reliant on fermentation are readily available and nearly foolproof. This is not only a testament to sourdough simply tasting damn good, but a rare and, perhaps, hungered for, connection to our beginnings. And those beginnings were their own happy, improbably successful accident. A sourdough starter was once a lifeline, guarded and cared for, whose continuation assured there would be a next loaf of bread. Starters were, and still are, shared with family and friends, and held with such affection, many are given names. Sourdough, in its way, is humbling.

Armed with centuries of wisdom, I once again headed to the kitchen. Using organic, whole grain flour and orange juice instead of water (a quick way to achieve the necessary acidity), and nestling the jar on a heating pad (Candida milleri is happiest around 78 degrees) I was finally successful in creating a sourdough starter that produces dense, tangy loaves. She resides on a corner of my meager counter space, bubbling and growing, practical and profound. I call her Candice.