A Wonderleaf question
Why do onions make people cry?
a real page from the book
Onions make people cry because cutting them breaks open their cells and mixes chemicals that were stored apart. The reaction makes a stinging gas, syn-propanethial-S-oxide, which floats to your eyes. There it meets the wet surface, irritates it, and your tear glands rinse the spot.
The onion uses this trick as protection while it grows in soil, where many small creatures might nibble. Your eyes are simply excellent at cleaning themselves, so the tears arrive fast. Chilling an onion first can slow the escaping gas a bit, a kitchen mercy.
Wonder words
- sulfur
- enzyme
- gas
- glands
Try it out
Cut an onion together, then compare one chilled slice with one room-temperature slice and notice which makes eyes water more.
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