Physics
Slicing an onion releases tear-inducing chemicals into the air, but the sharpness of the knife and the speed of the cut can affect how these droplets are expelled
By Alex Wilkins
Cutting onions can be a tearful experience
Foster.r/Getty Images
If you find yourself crying when chopping onions, physicists have found a possible solution – but professional chefs probably aren’t going to like it.
When onions are cut open, they spray a mixture of sulphur-rich compounds into the air, one of which is syn-propanethial-S-oxide, a chemical that triggers the nerves in the eye responsible for producing tears.
Sunghwan Jung at Cornell University in Ithaca, New York, and his colleagues used a high-speed camera to analyse in detail the spray produced when…
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