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Usually, the chemic mist released erstwhile onions are chopped – propanethial S-oxide – makes our eyes water. Now scientists person recovered a elemental mode to support those tears to a minimum.
In experiments by researchers from Cornell University successful the US, sharper blades and slower cuts importantly reduced the magnitude of bulb mist fixed disconnected during preparation, keeping eyes drier and room surfaces safer.
Biomechanist Zixuan Wu and squad utilized a mini guillotine, a high-resolution camera, and sensors to cautiously way the droplets expelled arsenic onions were cut, comparing mist characteristics against weapon sharpness, chopping speed, and cutting force.
Related: Scientists Reveal The Absolute Worst Thickness For a Paper Cut
"We recovered retired the velocity of the mist coming retired is overmuch higher compared to the velocity of the leaf cutting through," says physicist Sunghwan Jung.
The researchers utilized high-resolution imagery to way droplet travel. (Wu et al., PNAS, 2025)Every furniture successful an bulb has a apical and bottommost skin, and arsenic those layers are breached, the investigation showed determination are 2 resulting effects: an instantaneous detonation of mist, and past a slower seep of fluids done the layers.
Blunter knives created substantially much droplets and faster sprays, the researchers found. Because they necessitate much unit to interruption the skins, unit builds successful the onion's juices. Quicker, forceful cuts with a dull leaf propelled droplets adjacent farther.
The archetypal ejection of the droplets tin beryllium astatine precise precocious speeds, the observations showed, and tin get up to 40 meters per 2nd – that's 144 kilometers (89 miles) per hour. It's these droplets that airs the top threats to eyes.
The researchers were besides capable to debunk the communal mentation that chilled onions springiness disconnected little mist and are amended astatine reducing tears related to chopping. The starting somesthesia of the onions didn't look to marque immoderate existent difference; if anything, chilling them made things worse.
"These observations were supported by theoretical models that accurately seizure independently measured fracture forces," write the researchers successful their published paper.
The past of onions successful the room stretches backmost immoderate 5,000 years, and there's adjacent a notation of the tears that unrecorded successful an bulb successful Shakespeare's Antony and Cleopatra.
Now we person a overmuch amended thought of however the aerosols that origin those tears are created and released, and what tin beryllium done astir it. Using crisp blades and gentle cuts keeps the droplet mist beneath oculus level, the squad found.
This find has implications for nutrient safety, too. If bacteria are present, cutting benignant influences however they spread. As we saw with the E. coli outbreak astatine McDonald's successful the US conscionable past year, galore radical tin get sick precise rapidly done pathogens dispersed by onions.
"Suppose you person pathogens connected the precise apical furniture connected the onion," says Jung. "By cutting this bulb these pathogens tin go encapsulated successful droplets wherever they tin past spread."
The probe has been published successful PNAS.
