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Scientists have identified the chemical compounds that give sourdough bread the flavour and aroma that has made it such a hit with consumers.

Researchers from the Food Chemistry and Molecular Sensory Science at the Technical University of Munich say the information will help bakers – particularly those using industrial production processes – to measure the aroma and taste of loaves.

By using a combination of instrumental-analytical techniques and sensory analyses, scientists say the authentic flavour of sourdough rye bread crumb was decoded and recreated with 10 key tastants and 11 key odorants.

Three breads made by Munich bakery Ludwig Stocker Hofpfisterei GmbH were used in the study. These included a pure rye bread produced in a traditional three-stage sourdough bread-making process without the addition of lactic acid bacteria or yeast, a mixed-type bread, and a wheat bread.

Flavour recombination experiments identified that the key taste compounds in sourdough crumb are sodium, potassium, ammonium, chloride, magnesium, calcium, D-fructose, L-glutamic acid, acetic acid, and lactic acid.

The key aroma compounds were identified as acetic acid, butyric acid, vanillin, 3-methylbutyric acid, hexanal, 2,3-butanedione, phenylacetaldehyde, 3-methylbutanal, methional, (E,E)-decadienal, and (E)-2-nonenal.

Researchers said the study has enabled them to develop and validate an accurate and fast ultra-high performance liquid chromatography method that enables high-throughput study of the volatile key odorants and nonvolatile key tastants of sourdough bread crumb with the same instrumental setup.

Laura Eckrich, who conducted the project as part of her doctoral thesis, expects the new findings to benefit the baking industry. “We hope our findings and the quantification method we developed will help bakers achieve a consistent quality in their sourdoughs,” she said. ”For example, they can actively prevent the bread from becoming too sour.”

The researchers also investigated possibilities for reducing the salt content in bread and believe their findings could help reduce the amount of sodium in the dough while retaining the unique flavour.

The full study, which was written by Laura Sophie Amann, Oliver Frank, Corinna Dawid, and Thomas Frank Hofmann, is called ’The Sensory-Directed Elucidation of the Key Tastants and Odorants in Sourdough Bread Crumb’ and is published in the Foods 2022, 11, 2325 section of the MDPI website