In my kitchen, there is regular talk of yeast. There’s always a sourdough starter going, and kombucha bubbles away in the big glass jar on the counter. For me, these are little culinary reminders that the air around us is filled with wild yeast, ready to be captured and put to good use.
But it wasn’t always that way.
I used to associate yeast with a small packet of brownish granules that my mother used to bake with. I have memories of her pouring the active dry yeast into a measuring cup with a little warm water and waiting until it bubbled. Later I would learn that’s called “proofing”—essentially confirming that the yeast is still alive and able to do its job in the baking process—but as a small child it was just a bubbly brew in a measuring cup that smelled a little weird.
In a processed world, maybe it’s no surprise that we have reduced yeast to a mere packet of granules. But what that little packet doesn’t tell us is that yeast is everywhere, all around us, and essential part of our everyday existence.
I pondered this recently while reading Simran Sethi’s new book Bread, Wine, Chocolate: The Slow Loss of Foods We Love, an excellent look at loss of biodiversity through something that we all know, and love, well: food. Sethi takes us on a journey around the world, one that’s not just about understanding what’s at risk, but also reminding us to rejoice in what we eat. As I found through reading, yeast happens to be an instrumental part of all of the natural world, making me think about yeast in a whole new way.
“The only foods that sprang to mind when I thought of fermentation were sauerkraut, pickles, yogurt and kimchee. Not anymore. Bread, wine, coffee, chocolate and beer—they’re all fermented.”
“Microbes, including yeast, are everything. Not just in beer, but in life. The study of yeast is the study of us,” Sethi told me over e-mail. “We evolved from and are primarily made of microbes that are invisible to the naked eye and make up the largest number of organisms on the planet.”
Part of the fungi kingdom, yeasts fall under the same classification as bacteria and algae. Yeast is essentially everywhere, from the air we breathe, to the skin of a grape, to the soil that we walk on. “Although our bodies contain about 100 trillion cells, only 10 percent of them are human. The rest are microbes, weighing in at about 3 pounds in the average adult (about the same weight as our brain). Yeasts fortify our immune system, support digestive health and protect our cells against oxidative stress. We can’t live without them,” says Sethi.
As more and more research has been put into the importance of our microbiome (the term for the trillions of microorganisms that live on and in our body), there has been a growing interest in the importance of consuming fermented foods, which are full of beneficial bacteria.
The small yellow envelopes of dry granules ubiquitous with baking in the developed world represent a tiny fraction of the diversity and flavors of wild yeasts present all around us. Photo by Dan CC BY-ND
Thanks to yeast and bacteria, humans have been fermenting food and drink for centuries. “Fermentation is transformation,” says Sethi. “It’s an incredible process and one that tends to seed our guts with really wonderful flora.” While humans didn’t always understand that process, it left them in awe. “Historically, people didn’t understand yeast. They knew something was responsible for turning a sweet, grainy precursor to beer into alcohol, but they weren’t exactly sure what it was or how it happened.”
Nowadays, we have a better understanding of how these things work—for example, we know that yeast is responsible for turning sugars to alcohol—but when we talk about fermented foods, most of us only think of a handful of things we eat, forgetting that fermentation is an essential process in many of foods (and drinks) that we love.
With a title like Bread, Wine, Chocolate, you can imagine what Sethi focused on in terms of food in her book; you can also add beer, coffee and wine to the list. “The foods I selected went through many permutations and were chosen with great care after countless hours of consideration (or, some would say, obsession). They’re all foods that stimulate, soothe and nourish us in multiple ways,” says Sethi. Her sister pointed out that her chosen foods were vices; a friend turned her attention to the fact that they also were all fermented. “The pleasure I was aware of, but I didn’t anticipate the connection to fermentation. The only foods that sprang to mind when I thought of fermentation were sauerkraut, pickles, yogurt and kimchee. Not anymore. Bread, wine, coffee, chocolate and beer—they’re all fermented.”
Wild yeasts aren’t just microorganisms with transformative powers, they are also an expression of place. It’s why a San Francisco sourdough starter taken out of its home will eventually adapt to whatever kitchen it’s in, its flavor changing and evolving. When we hear the word “terroir,” we may think of wine, but as Sethi points out in her book, terroir is really a “taste of place.”
In that sense, when we are talking about yeasts, terroir can be found in bread, beer and beyond. Unfortunately, most of us are used to the industrial versions, which do very little when it comes to expressing place. “The yeasts we buy in groceries are domesticated—as different from wild yeast as modern corn is from the teosinte grass it evolved from. But yeast actively contributes to flavor,” says Sethi. She points to the example of Lambic ales, known for their funky, sour taste; a reflection of where they are made. “Belgian brewers, for instance, have made Lambic ales with wild yeast for over 500 years—a celebration of wild yeast and the rich biodiversity of the Senne river valley, a 15-by-75-mile region south and west of Brussels. They leave wort overnight in shallow pans called coolships, exposing the liquid to yeast and bacteria of the Senne river valley.” Thanks to yeast, a glass of wine, a bottle of beer or a loaf of bread all have the potential to share with you where they come from, their taste as much a reflection of place as the artisanship that went into making them.
Whether or not we spend time in the kitchen, it’s clear that yeast deserves a little more of our attention, and gratitude. “As I write, I’m not a brewer or a baker. The only yeast I had ever thought about was from a completely different genus, Candida albicans, the one responsible for yeast infections and not something I felt particularly grateful for. But yeast is something for which we should have immense gratitude,” says Sethi. “These microbes have helped shed light on a number of basic life processes and not only contribute to the flavor of foods, but help us understand who we are.”
Anna Brones is the author of The Culinary Cyclist and Fika: The Art of the Swedish Coffee Break and runs Foodie Underground, a site about real food for real people. Wherever she is in the world, she can often be found riding a bicycle in search of excellent coffee.
Sourdough starter photo by julochka CC BY-NC