Erin McKenney, Ph.D., postdoctoral researcher at North Carolina State University, presented the latest results from the Citizen Science Sourdough Project as keynote speaker at the International Symposium on Bread on June 12-14 at Johnson & Wales University’s campus in Charlotte, North Carolina.
Aiming to examine the microbial diversity of sourdough starters from around the world, the sourdough project began three years ago with a global questionnaire that included such questions as “how old is the starter?” and “how old are you?” Therefore, variables under examination included both the sourdough starter and the person who created it.
Nearly 600 participants in 17 countries sent in sourdough starters (some packages were “inflated like balloons,” McKenney recalled). Having cultures in hand enabled the researchers to perform experiments and conduct DNA sequencing, “to take a roll call of these bacteria,” McKenney said. They curated the meta data to further interpret the results.
“We found over 70 types of lactic acid bacteria,” she said, adding that Lactobacillus sanfranciscensis made up a big block of the bacteria identified and Saccharomyces cerevisiae (a common yeast) was present in more than 75% of samples. “When we turned to the microbes themselves, we took the five most common bacteria and the five most common yeasts and conducted a comparison study, two at a time. We started to find a family tree of starters.”
“We identified 15 clusters, simple and distinct,” McKenney said. “The next step is to study what do these clusters have to do with flavor and the end product itself.”
McKenney studies how microbial communities form over time and how they adapt to their environments. Recently, she has expanded her research to sourdough and other fermented foods. Microbial cultures lie at the heart of human cultures, and fermented foods provide accessible systems for studying microbiology and nutrition without formal laboratory equipment.
Puratos was the presenting sponsor for the third time of Johnson & Wales University’s annual International Symposium on Bread, which featured a new, interactive format. Attendees were invited to focus on an area of interest from one of three themes:
- The Future of Bread Lies in Its Past: New Frontiers in Sourdough Microbiology
- Local, Ancient, and Heirloom Grains: The Farmer/Miller/Baker Connection in Baking with Landrace, Heirloom, Regionally Specific, and Polycrop Grains
- Good Bread is Good for You: Wellness and Healthfulness in the Future of Bread
The symposium was curated by Johnson & Wales faculty member and noted author Peter Reinhart, who wrote The Bread Baker’s Apprentice and 10 other books on bread.
“For me, one of the greatest joys of this event is watching a movement grow,” Reinhart said.
In the hands-on session, The Future of Bread Lies in Its Past: New Frontiers in Sourdough Microbiology, Melina Kelson CMB, educator and owner, Bootleg Batard Bakery and board member of The Bread Bakers Guild of America, explained that the goal of the workshop was to use the same canvas to compare how different sourdoughs behave when fed at different rates.
Sarah Owens of Ritual Fine Foods, New York City, and author of “Sourdough: Rustic Fermented Breads, Sweets, Savories, and More,” said they created six starters with different flours and maintained in different ways, resulting in “significant differences” in flavors.
“There was a broad spectrum of results, and each one had a really different expression,” she said. “Sourdough has so much flexibility, depending on time, temperature, flour and shaping.”
Sourdough bread continues to gain popularity in the United States, as consumers migrate to breads produced with long and natural fermentation. Clean label bread products have increased in sales significantly over the past year.