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Burning Question: Why Do Raw Onions Make You Cry?

If you've ever chopped raw onions to add a bite to pico de gallo or crunch to a hamburger, chances are, you've found yourself tearing up over the cutting board. But why is this single vegetable, only in raw form, solely responsible for a great deal of weeping?

Along with chives, garlic, and leeks, onions fall under the allium genus. These plants are known to absorb sulfur from soil, which aids in the formation of volatile molecules called amino acid sulfoxides. When an onion is cut, it releases enzymes that break these sulfoxides down. Then a second type of enzymes converts into a gas that irritates the eyes. When the onion's vapors reach your face, the cornea of the eye signals gland cells to wash the irritant away with tears.

While green onions, shallots, leeks, and garlic produce the same gases, these vegetables produce much less of them, and won't make you cry. When you cook an onion, you're actually rendering certain enzymes inactive, so vapors don't burn your eyes. Although a tearless onion has been developed, if you don't have one on hand, simply remember to chop onions last.

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Join The Conversation
sugar_me_sweet sugar_me_sweet 8 years
Yeah, I also heard that putting onions in the fridge before chopping helps.
bengalspice bengalspice 8 years
Doesn't putting the onion in the fridge before chopping help?
lisabarn lisabarn 8 years
I cry buckets! but after doing some online research, I discovered if I put a big glass of water next to the cutting board to give those nasty enzymes somewhere else to go, it helps.
jesssa jesssa 8 years
i dont eat onions so i haven't really had to use them a lot in the past. but last week i was making a salad dressing that needed them and so did the salad and suddenly i was like AHHH my EYES!!! lol... i didn't really realize how true it was until it happened to me :P
doogirl doogirl 8 years
They developed a tearless onion? Seriously? We have war and famine and they're developing an onion so we don't tear up? Unbelievable!
aimeeb aimeeb 8 years
Now I know...thanks!
Greemy Greemy 8 years
Thank goodness for contacts, as I too chop, dice and slice lots of onions with not a hint of tears.
dclsweetspot dclsweetspot 8 years
I use a lot of onions and luckily contact lenses have stopped my eyes from burning. They haven't bothered me for years.
smileyface smileyface 8 years
I was just wondering this last night when I was cutting up an onion. Thanks Yum!
kia kia 8 years
I am a nerd and keep a set of chemistry goggles on a hook attached to my hanging pot rack if I have to chop a lot of onions. If it is a simple chop job not calling for a whole onion I also score the onion in a grid and then slice. It is a fast way to get through it for me.
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