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How One Seattle Baker Uses Infused 'Yeast Water' To Leaven Bread

Courtesy of Rika Manabe
Junko MIne kneads dough using fermented yeast water.

When Junko Mine gets ready to bake, she starts with a big glass jar.

She fills it with water, then adds something for flavor: maybe a few raspberries, some Douglas fir needles or a whole apple, skin and all.

She seals the jar tightly, then waits. For five to seven days.

Inside the jar, things start to happen.

“You see bubbles. You see the carbonation,” Mine says.

As the days pass, the bubbles build. A jar of raisin water once built up so much pressure that when Mine finally opened it, it might as well have been champagne.

“Raisins flew all over — on the couch, the table! I had to clean,” she says.

Credit Courtesy of Rika Manabe
Courtesy of Rika Manabe
Fruit-infused jars of yeast water rest in the sunlight.

What Mine ends up with in these jars, other than the occasional threat of an explosive mess, is wild yeast. Like a sourdough starter, this method makes uses of the naturally occurring yeast in the air (yeast surrounds us, though we don’t see it). Over the days, the airborne yeast begins to colonize inside the jar. It feeds on the sugars of the fruit or plants and turns them into alcohol and carbon dioxide, eventually creating bubbles that signal fermentation. It becomes what Mine calls “yeast water.”

“It’s like beer or wine. And then I use that yeast water to make bread,” Mine says.

Some ingredients take longer to ferment depending on the sugar content of the jar and the temperature of the room, says Mine, but most require about a week's time before it can properly leaven bread. She then uses the resulting yeast water as a substitute for yeast and at least part of the liquid that a recipe might call for. If a recipe calls for two cups of water, for example, she might use one cup of plain water and substitute the second with yeast water.

Credit Courtesy of Rika Manabe
Courtesy of Rika Manabe
Junko Mine gathers ingredients for yeast water.

Figuring out the exact measurements of the substitution takes a bit of tinkering, says Mine, but wild yeast affords a unique way to enjoy seasonal flavors. 

“Depending on what you use, you get a different flavor. When I made bread with wild rose, it had a hint of rose aroma. Or when I made yeast from cherry blossom petals, it had a really strong cherry blossom smell,” she says.

But why go through the trouble of fermenting and waiting instead of adding the desired flavor directly to the dough? It’s a question Mine gets asked often.

Credit Courtesy of Rika Manabe
Courtesy of Rika Manabe
Junko Mine's wild-yeast loaves rest on a table.

“My friend said, ‘Why do you want to make yeast? You can just make a blend, like strawberry juice, and put it inside the bread dough.’ But I said, ‘It’s not the same to me. I like the hint of taste. It’s a different flavor,”’ she says, adding the method also yields a loaf with a chewy inside and a crusty outside.

Mine, a professional baker, admits the process is labor-intensive. Unlike a sourdough starter, which can live infinitely as long as it’s fed fresh flour and water, these wild yeast starters aren’t immortal. Once Mine uses the water, she refills the same jar just once and ferments again before tossing the remains and starting anew. Any more brews and the flavor gets too diluted, she says.

Finding A Teacher Of The Esoteric Art

Mine hasn’t always been a scenic-route baker. It all started when she came across a photo of a jar of wild yeast, the water dyed the bright hue of the flavoring agent.  

“The color was so beautiful. I said, ‘What is this?’” she says. “It was like a really vivid red and purple. I’d never seen [yeast] like this.”

She learned the baker, Taro Hashiguchi, only uses wild yeast derived from the fruits, herbs and flowers his own father grows in the garden, and as a result, only opens for business two days a week. Still, people from all over Japan go to buy his bread at his shop, Taro-ya, just outside of Tokyo.

Mine was immediately intrigued. She wrote the baker a letter, asking him for a lesson in the art of wild yeast baking.

“And he said, ‘I want to help you. I don’t know what I can do, but I want to show you what I do,’” she says.

So off to Japan she went for a three-day apprenticeship filled with yeast waters of various types, from yuzu to strawberries, to osmanthus flowers. And since she went wild, she hasn’t looked back.

“I used to use dry yeast to make bread, but I don’t want to anymore,” she says. “Right now, I’m making persimmon [yeast water].”

Exploring The Look — And The Sound — Of Yeast

Mine has come to appreciate yeast as more than just a leaven. Somewhere in between the hundreds of hours spent watching and waiting for fermentation, yeast itself has swelled into an art subject beyond her kitchen. As she puts it, Mine wants to “make music from the bread.”

The baker wants to sequence the DNA of her starters, then make music by assigning a key to each of the four bases of a DNA strand. To this end, she’s found a mentor in geneticist Aimee Dudley, who uses wild yeast to study human disease at the Pacific Northwest Diabetes Institute. Dudley has taught Mine to isolate the yeast off of, say, the flower petal or the fruit.

“She’s this really Renaissance kind of person,” says Dudley of Mine.

Mine’s ultimate hope is to share with others how she now sees yeast. In addition to baking with wild yeast in some commercial capacity, she also wants to build an art exhibit with yeast as the focus. The exhibit would showcase videos and images of wild yeast to the music of their DNA sequence.

Do Try This At Home

Mine encourages curious home bakers to experiment with wild yeast. For the hesitant, an easy first step might be to use a fermented drink instead of trying to make yeast water from scratch.

“What I do, like making yeast water from fruits or herb, it’s kind of difficult. Some people say, ‘I’ve done that before, but it didn’t work,’” she says. “I’ve made bread with kombucha, and the outcome was wonderful. Maybe for a beginner, they could start with kombucha or some other fermented beverage, like beer.”