When Covid-19 hit the US, some of the biggest quarantine coping mechanisms all revolved around a fan favorite carbohydrate: bread. With the copious amount of time on people’s hands, baking sourdough bread was the perfect activity.

Unlike any other bread, it’s hard to get the perfect tasting sourdough. Research has found that there are biological reasons behind sourdough bread and its taste, but before doing so, it’s important to learn what sourdough bread is made up of, and how it’s made. To help learn more about the process of making sourdough bread from scratch, I got a mini crash course from Little Spoon Farm. The starter (initial mixture) contains flour and water and sometimes salt, which will eventually grow into a diverse selection of microbes (these are tiny living organisms, which in this case are bacteria). The starter has to sit for 7-14 days, and within that time, the starter grows through the flour by eating the sugars within itself. With that growth comes bacteria/microbes and lactic acid, which eventually will allow the bread to be able to leaven in the oven.

Recent studies have shown that each starter is made up of different microbes. One study had 18 professional bakers from all around the globe make their sourdough, and send it to a lab in Belgium, where DNA sequencing was used to identify the microbes in the different starters. Although there were common yeasts and acids found like Saccharomyces cerevisiae and Lactobacillus, the strands and amount of each differed according to the starter. Another study done by Elizabeth Landis, at Tufts University, looked at 560 different starters submitted from all around the world. Through doing so, she found recurring microbe groups within these different sequences. There is still no definitive reason behind the microbe groupings, and why exactly they differ for each starter, but Landis mentioned that certain yeasts “specialize in feeding on distinct sugars,” due to the fact that they are made of different sugar mixtures. Some yeast also lack certain enzymes, which as we learned in class, help break down molecules. In this specific situation, the enzymes within different yeasts feed on and break down sugars. Differing yeasts could also be a reason why sourdough bread has different flavors. (Keep in mind that Landis’ findings are still under review, so there are still limited details on this experiment and not definitive reasoning).

Microbial ecologist, Erin McKenny, further elaborates on how “each microbial community can produce its own unique flavor profile.” For example, when more acetic acid is present in the starter, the bread will have a more sharp and vinegary taste. When the starter produces more lactic acid, it has a more sour and yogurt like taste. Metabolic byproducts within the starter could also potentially add to the complexity of the sourdoughs’ taste. In addition to each microbial community, scientists have identified other features that influence the taste of the bread like temperature. When lactic acid ferments in a warmer area, the bread has a more sour taste, and when it ferments in a colder area, the bread has a more fruity taste.

After looking at multiple articles showing how bakers get their sourdough to have a certain taste, I have learned how important the specifics are when it comes down to making sourdough. One article that gave tips on how to manipulate the taste of sourdough reinforces everything that the main article helped explain, and talks about the importance of keeping a warmer, dry climate to ensure that the bread tastes sour. It turns out that a quarantine treat may be a bit more complex than it appears. It’s interesting to see how biology plays a key role in one of the most prominent foods, and next time you consider making sourdough or get a bread basket from the Cheesecake Factory, you’ll now know the biology behind it.

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