Sweaty, vinegary and sweet odors mingle to make dark chocolate’s smell

Researchers reconstructed the aroma in the lab


NOSE GOES  Researchers concocted the smell of two dark chocolate bars from their odor-producing compounds.

Charisse Kenion/Unsplash

Scientists have sniffed out the chemicals that give some dark chocolates their smell.

The compounds that mingle to make the candy’s aroma include pleasant-smelling ones such as vanillin, which gives vanilla its smell, and flowery linalool. But other molecules produce smoky or vinegary odors and even one that smells like sweat, researchers report online May 8 in the Journal of Agricultural and Food Chemistry

“These single odorants usually never have the typical smell of the food itself,” says Michael Granvogl, a food chemist at the University of Hohenheim in Stuttgart, Germany. Instead, in any given food, the scent depends on which molecules are present and at what level, he says.

Granvogl and his colleague Carolin Seyfried of the Technical University of Munich picked two particularly aromatic chocolate bars having at least 90 percent cocoa content from a grocery store. The pair crushed up each of the treats and extracted their volatile compounds, those that vaporize easily and can waft up to our noses to be smelled.

Of the roughly 70 aroma-producing volatile chemicals detected, between 28 and 30 occurred in each bar at high enough levels for humans to smell. By combining these compounds at roughly the same concentrations as in the original chocolate bars, the scientists re-created each bar’s aroma. A panel of more than 20 people with trained noses sniffed the concoctions and found that they smelled similar to the real deal. The study is the first to reconstruct dark chocolate’s smell from odor compounds measured using state-of-the-art techniques, the researchers say.

Carolyn Wilke is a freelance science journalist based in Chicago and former staff writer at Science News for Students. She has a Ph.D. in environmental engineering from Northwestern University.

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