Science · 6 pages · 12 min
Why onions make eyes sting
A cut onion mixes enzymes with sulfur compounds and releases a gas that irritates the eye.
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From the opening
Onions make eyes sting because cutting lets enzymes meet sulfur compounds that intact cells kept apart, and one product is a gas that reaches the eye. The sting is that airborne molecule in the tear film, not a spray of onion juice across the kitchen. The opening covers why the cut starts the chemistry, what the volatile factor is, and why garlic is not the same sting.
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Inside
- Why the cut starts the chemistry
- What the volatile factor is
- Why garlic is not the same sting
- Why cooking stops the new gas
- Where the idea stops applying
- A distinction worth keeping
Sources
- Alliinase and lachrymatory-factor synthase in damaged onion cells
- Syn-propanethial-S-oxide, the volatile that reaches the eye