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A staple of lockdown kitchens and bakeries across the world, sourdough is famed for its unique, tangy flavor. New research, presented at the American Chemical Society (ACS) Fall 2023 conference, has identified what makes sourdough taste so good.
The importance of the starter
The wild yeast and microbes found in the starter of a sourdough cause the bread to rise by consuming the carbohydrates in the flour and producing carbon dioxide, which gives the bread its characteristic airy texture. Early sourdough research revealed that over 50 types of lactic acid bacteria and over 20 species of yeast can thrive in sourdough starters.
As the starter uses wild yeast and microbes, starters across the world can vary. San Francisco is particularly famed for its sourdough, with some bakeries using the same starters in their recipes for around 170 years. It has been rumored that the foggy environment of the city plays a role in the taste of the sourdough, with the loaves once thought to contain a unique bacterium dubbed Lactobacillus sanfranciscensis, which was later found across the world.
The essence of sourdough
The taste of sourdough can be influenced by factors including fermentation time, temperature and flour type, as well as the microbes present in the starter.
A research team has identified the compounds responsible for sourdough's unique taste, finding 11 odorants and 10 tastants using a technique called sensomics.
“With sensomics, you can take just a few key compounds and completely recreate the characteristic taste of a food,” said Laura Eckrich, who presented the team’s research at ACS Fall 2023.
Sensomics uses data from chromatography, mass spectrometry and other techniques to isolate and quantify key molecules from food – in this case, the crumb of the sourdough – enabling researchers to piece together the food’s “essence”.
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The sourdough essence was then confirmed to match the smell and taste of sourdough bread by a human sensory panel.
The key tastants in sourdough include salt, acetic acid and lactic acid. Salt is added to the loaves by the baker, but acetic and lactic acids are the byproducts of fermentation. The researchers then compared the concentrations of these compounds in sourdough with yeast-based breads, made with either rye or wheat flour.
Although yeast-based breads did contain lactic and acetic acids, they were present in much lower concentrations than in sourdough, confirming the importance of the fermentation process for developing flavor in a sourdough loaf.
Of benefit to bakers
This new research could help bakers control the quality and consistency of their loaves and prevent waste from loaves that are too sour. It can also help optimize the amount of salt bakers add to their sourdough.
“This was the first time the key taste and aroma compounds of bread crumb were elucidated using the sensomics approach, and we hope what we learned will help bakers create the best sourdough breads they can,” said Eckrich.
Reference: Amann LS, Frank O, Dawid C, Hofmann TF. The sensory-directed elucidation of the key tastants and odorants in sourdough bread crumb. Foods. 2022;11(15):2325. doi: 10.3390/foods11152325
This article is a rework of a press release issued by The American Chemical Society. Material has been edited for length and content.
FAQs
The key tastants in sourdough include salt, acetic acid and lactic acid. Salt is added to the loaves by the baker, but acetic and lactic acids are the byproducts of fermentation.
What gives sourdough bread its unique flavor? ›
Sourdough bread's signature taste comes from friendly bacteria and yeast, which produce flavorful lactic and acetic acids in rising bread dough.
Why does sourdough bread have a distinct taste? ›
Bacteria, colored blue, metabolize sugars and release byproducts such as lactic acid and acetic acid. These byproducts act as a preservative and are what give the starter its distinctive sour smell and taste.
Why is sourdough unique? ›
What makes sourdough unique. Mass-produced wheat and white breads rely on baker's yeast, the fungus Saccharomyces cerevisiae, to rise. Sourdough, in comparison, uses a combination of wild yeast and microbes to help the bread rise through fermentation.
Why is sourdough bread so delicious? ›
Thanks to the lactic and acetic acids that ferment the dough and provide its characteristic tang, the flavour is vastly superior.
Why is sourdough healthier? ›
Sourdough bread may be easier to digest than white bread for some people. According to some studies, sourdough bread acts as a prebiotic, which means that the fiber in the bread helps feed the “good” bacteria in your intestines. These bacteria are important for maintaining a stable, healthy digestive system.
What is the secret to sourdough? ›
The secret to sourdough is simple: water. The more water you add to your dough will affect how open the crumb (bigger holes and softer texture) will be once it's baked.
Why can I eat sourdough but not normal bread? ›
Sourdough is not gluten free, but we know that many people with IBS, gluten intolerance, or gluten sensitivity can tolerate sourdough bread. This is because the methods used to make sourdough break down some of the gluten in the flour so it is easier to digest. Think of sourdough as low-gluten rather than gluten-free.
Is sourdough healthier than white bread? ›
The bottom line. Sourdough is a healthier alternative to regular white or whole wheat bread. Although it has comparable nutrients, the lower phytate levels mean it is more digestible and nutritious. The prebiotics also help to keep your gut bacteria happy, and it may be less likely to spike blood sugar levels.
Is Lidl sourdough real? ›
Most of the flour is wheat, not rye. The use of baker's yeast means this is not genuine sourdough bread, so Lidl using the word in its name makes it what the Real Bread Campaign calls sourfaux.
Health benefits of sourdough. The type of flour used — all-purpose, whole wheat, rye — can affect the nutritional content of sourdough bread, says Wee. But generally speaking, sourdough bread is a healthy option and can be eaten regularly as part of a nutritious, balanced diet.
Why is sourdough good for your gut? ›
Simply put, the phytase enzymes released by the yeasts as the dough acidifies effectively pre-digest the flour, which releases the micronutrients and in turn reduces bloating and digestive discomfort.
Why don't some people like sourdough? ›
The taste of the wheat is greatly subdued, being overpowered by sour. Some people would greatly prefer the yeasted bread.
Why does everyone love sourdough? ›
Unlike bread made with commercial yeast, sourdough relies on wild yeasts and bacteria in its environment. This process, known as fermentation, gives sourdough its distinctive tangy flavor. It also breaks down gluten more extensively than regular bread-making techniques, potentially making it easier to digest.
How does sourdough get its flavor? ›
Sourdough is a stable culture of lactic acid bacteria and yeast in a mixture of flour and water. Broadly speaking, the yeast produces gas (carbon dioxide) which leavens the dough, and the lactic acid bacteria produce lactic acid, which contributes flavor in the form of sourness.
What element makes the sourdough bread special? ›
Sourdough bread also naturally contains varying levels of acetic acid bacteria, a group of bacteria that give sourdough bread its particular vinegar-like aroma. Starters with high levels of acetic acid bacteria also take longer to ferment and rise, giving sourdough bread its characteristic texture ( 5 , 8 ).
What make sourdough bread different? ›
Sourdough is naturally leavened bread, which means it doesn't use commercial yeast to rise. Instead, it uses a 'starter' – a fermented flour and water mixture that contains wild yeast and good bacteria – to rise. This also produces the tangy flavour and slightly chewy texture you'll find in sourdough.
Why does sourdough bread have a unique taste and chewy texture? ›
The long, slow fermentation process that sourdough requires allows the yeast and bacteria to break down the proteins in the flour, making it easier to digest and giving the bread a chewy texture. In addition to contributing to the flavor and texture of sourdough bread, the yeast in sourdough has other benefits as well.
What is the Speciality of sourdough bread? ›
Sourdough bread is completely natural, as there are no additives from yeast, and it's a rich source of vitamins and minerals. The lactic acid bacteria found naturally in a sourdough starter is the same good bacteria that's found in other fermented foods, like kimchi, kefir and sauerkraut, which are good for gut health.
