San Antonio Couple Pairs Science, Sustainability with Search for Local Yeasts

For their third date, Texas Cultures Laboratories founders Mara and Rob Green spent a week camping in Colorado Bend. Last month, they got married there. Such excursions have become a centerpiece of their relationship and the engine of their professional passion: hunting down the microorganisms that will fuel the future of Texas craft beer.

Trained as a theologian and biologist, respectively, at the University of the Incarnate Word, Mara and Rob started Texas Cultures in 2016. During a conversation at their home/laboratory in Olmos Park Terrace, Rob cited a chat from his time working at the Granary ‘Cue & Brew as the genesis of this yeast quest.

“As the exact conversation would go, I one day asked Alex [Rattay, then-head brewer at the Granary] about the origin of barleywine yeast,” Rob said. “As he explained its English roots, I wondered if all beers could possess their own terroir — and where are all the American yeasts?”

To answer those questions, the Greens began blending their love of the outdoors with their passion for science, sustainability and the promise of truly singular yeasts for Texas brewers.

Rather than capturing yeast via coolship or other traditional methods, Texas Cultures gathers specimens in sterilized collection vials. Using what Mara describes as the “pick-shove-pop-snap” method, yeast hunters can bottle up any natural source of sugar — flowers, fruit, tree sap — then send it back to the lab for analysis and, if the yeast passes muster, cultivate it in a propagation tank. The results literally capture flavors and functions particular to a single time and place, a fact that the Greens highlight in profiles for each yeast, complete with brewing specs, flavor, profiles and pictures of the source plant.
There are ecological advantages also.

“Locally-produced yeast reduces the environmental impact of shipping yeast in from California, usually an overnight shipment,” Rob said. “This allows for a healthier yeast, lower yeast prices and a much shorter production lead time in ordering.”
Texas Cultures use saisons as the control for brewing yeast candidates. As we sampled several bottles over the course of our interview (in the name of science, of course), strains gathered from across the state revealed a breathtaking diversity. One yeast harvested off a cactus blossom in Big Bend delivered bright springtime flavors; another, collected from a yucca plant just 70 miles away, favored an earthy profile. A personal favorite was the Buttercup, which carried all the floral sweetness of its namesake.

Texas Cultures has already won admirers in the brewing community. They include fellow scientist/brewer Tim Castaneda of Black Laboratory Brewing, who pitched one of the lab’s early strains in a citrusy, dry pale ale. He sees a demand for locally-produced and housed yeast, both for creativity and quality control reasons.

“Most big laboratories will make a lot of yeast and store it in their cooler, where it has a shelf life of up to several months, but as each week passes a certain percentage of yeast begins to die and will go dormant,” Castaneda said in an email to the Current. “Texas Cultures prepares your order when you order it, meaning that you get 100 percent viability and it is typically still highly active and ready to be pitched.”

Texas Cultures contributes to non-brewing applications for yeast as well. The Greens are currently conducting field research in the Big Thicket and Government Canyon to collect yeasts that consume sugars so fast they might prove a natural foil to plant-killing fungi and molds.

Both Greens are going to graduate school in the fall — he for biotechnology, she for environmental sustainability — in order to support the lab’s long-term dreams. Those dreams include a community yeast bank sourced from Texas and beyond, as well as hiring staff to oversee day-to-day operations — which would allow the Greens to spend lots of quality time together out in the field.

So, what should a first-time collector look for when foraging?

“You want the one that’s farthest away from people, and not in baking 102-degree weather, in slightly dappled sunlight, and a little bit more humid and the butterflies are going to that one,” Mara said, laughing. “You’re like, ‘That’s the one.’ The one the butterflies are drinking from, that’s the one!”

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