The science behind sourdough’s distinctive tang

Scientists have identified and quantified 21 chemical compounds that contribute to sourdough’s unique flavour.

Instead of baker’s yeast, sourdough breads use a “starter” consisting of living bacteria and wild yeast. 

Publishing in Foods, researchers from the Technical University of Munich separated and analysed the characteristic flavours behind the bread using gas chromatography, and mass spectrometry.

The scientific approach of isolating, identifying and quantifying different flavour and aroma compounds in food is called sensomics.

“With sensomics, you can take just a few key compounds and completely recreate the characteristic taste of a food,” says Laura Eckrich, who is presenting the research at the American Chemical Society meeting.

Researchers identified 10 key taste characteristics and 11 key odour elements, quantifying how much of each makes a great tasting sourdough.

They then tested their findings, creating a ‘sourdough essence’ made up of the compounds.

The results reveal the vital importance of the fermentation process to sourdough’s taste. Salt (an ingredient added to the bread mix) along with acetic and lactic acid (resulting from fermentation) were the key components of sourdough taste.

Other taste compounds include potassium (bitter or salty), ammonium, chloride, magnesium, calcium, d-fructose, and l-glutamic acid.

Key aroma compounds include acidic or cheesy smells, acetic acid, butyric acid and 3-methylbutyric acid, vanillin (vanilla), hexanal (fresh cut grass), 2,3-butanedione (buttery), phenylacetaldehyde (sweet, honey-like), 3-methylbutanal (fruity or cocoa smell), methional and (E)-2-nonenal (vegetable or cucumber scents), (E,E)-decadienal (nutty or fried).

“This was the first time the key taste and aroma compounds of bread crumbs were elucidated using the sensomics approach, and we hope what we learned will help bakers create the best sourdough breads they can,” says Eckrich.