Sourdough may look simple, but it is powered by a surprisingly complex world of microbes. New research shows that while the same yeast tends to dominate sourdough starters regardless of flour, the bacteria change depending on the grain used. Those shifts help shape how dough ferments and how bread ultimately tastes and feels.
Credit: Shutterstock
The flour you choose helps decide which microbes run your sourdough and how it tastes.
Sourdough starter is made from just flour and water, yet it supports a complex process that bakers rely on every day. Beyond baking, it also offers scientists a unique window into how microorganisms interact and evolve. The familiar chewiness and tangy flavor of sourdough come from microbes that ferment the dough. Previous research has identified more than 60 different bacterial genera and over 80 yeast species in sourdough starters collected worldwide. “We can use sourdough as an experimental evolution framework, to see what happens over time,” said evolutionary biologist Caiti Heil, Ph.D.
How Flour Type Shapes Sourdough Microbes
In a recent study published in Microbiology Spectrum, Heil and her colleagues at North Carolina State University in Raleigh examined how different flours influence the microbes that grow in sourdough starters. Their analysis showed that yeasts belonging to the genus Kazachstania were the most common in every starter they tested. In contrast, the bacterial communities differed depending on which type of flour was used.
Why Flour Choice Matters for Bakers
The results suggest that switching flours can change the microbial balance of a starter. “And because the microbial composition affects different traits, by altering the flour you could potentially alter how your bread tastes,” said Heil, the senior author of the study. More broadly, she explained that the findings demonstrate how sensitive the sourdough microbiome is to environmental factors.
Many Influences on the Sourdough Microbiome
Earlier studies have shown that sourdough microbes are shaped by several factors. These include the ingredients used, the surrounding air and kitchen surfaces, and even the hands of the baker. Bakers also work with a wide range of grains, such as wheat, rye, barley, teff, and millet. Each grain provides a different set of nutrients that microbes use to grow and compete.
Earlier studies have shown that sourdough microbes are shaped by several factors. These include the ingredients used, the surrounding air and kitchen surfaces, and even the hands of the baker. Bakers also work with a wide range of grains, such as wheat, rye, barley, teff, and millet. Each grain provides a different set of nutrients that microbes use to grow and compete.
A Classroom Project Sparks Scientific Research
The study began with an educational project led by Enrique Schwarzkopf, Ph.D., a postdoctoral researcher in Heil’s lab and an avid sourdough baker. He launched a program at a local middle school to teach students about fermentation and evolution. Schwarzkopf, who maintains a sourdough starter named Seth, used the starter as a hands-on teaching tool. Students experimented with different flour combinations and feeding schedules to see which starter would grow the fastest.
Tracking Microbes With Genetic Tools
To study the starters, Heil and her team used metabarcoding, a technique that scans genetic material to identify which microbes are present. Each starter began with one of three substrates: all-purpose flour, bread flour, or whole wheat flour. At the start of the experiment, the flours contained similar bacterial communities along with a variety of yeasts.
The study began with an educational project led by Enrique Schwarzkopf, Ph.D., a postdoctoral researcher in Heil’s lab and an avid sourdough baker. He launched a program at a local middle school to teach students about fermentation and evolution. Schwarzkopf, who maintains a sourdough starter named Seth, used the starter as a hands-on teaching tool. Students experimented with different flour combinations and feeding schedules to see which starter would grow the fastest.
Tracking Microbes With Genetic Tools
To study the starters, Heil and her team used metabarcoding, a technique that scans genetic material to identify which microbes are present. Each starter began with one of three substrates: all-purpose flour, bread flour, or whole wheat flour. At the start of the experiment, the flours contained similar bacterial communities along with a variety of yeasts.
Unexpected Results From Fermentation
After several weeks of repeated feeding, the microbial communities changed. The starters all became dominated by the same yeast, while the bacteria showed greater variation. Heil said she initially expected to find Saccharomyces cerevisiae, or brewer’s yeast, which is commonly used in baking and is central to many of her lab’s research projects.
Instead, Kazachstania emerged as the most abundant yeast in every starter, regardless of flour type or feeding schedule. Genetic analysis also revealed differences among bacteria. Starters made with whole wheat flour contained higher levels of Companilactobacillus, while starters made with bread flour showed increased levels of Levilactobacillus.
After several weeks of repeated feeding, the microbial communities changed. The starters all became dominated by the same yeast, while the bacteria showed greater variation. Heil said she initially expected to find Saccharomyces cerevisiae, or brewer’s yeast, which is commonly used in baking and is central to many of her lab’s research projects.
Instead, Kazachstania emerged as the most abundant yeast in every starter, regardless of flour type or feeding schedule. Genetic analysis also revealed differences among bacteria. Starters made with whole wheat flour contained higher levels of Companilactobacillus, while starters made with bread flour showed increased levels of Levilactobacillus.
Flour as an Ecological Driver
Heil, whose research focuses on how organisms adapt to new environments and compete at the genetic level, explained that each flour type creates different nutritional conditions. Linking those substrates to the environments microbes experience, she said, can help scientists better understand how diverse microbial communities form, compete, and persist.
Heil, whose research focuses on how organisms adapt to new environments and compete at the genetic level, explained that each flour type creates different nutritional conditions. Linking those substrates to the environments microbes experience, she said, can help scientists better understand how diverse microbial communities form, compete, and persist.
The Life of Earth
https://chuckincardinal.blogspot.com/
No comments:
Post a Comment
Stick to the subject, NO religion, or Party politics