Why does it happen?!
Why does it happen?
Why do onions make us cry and have runny noses? What's in it that causes this? And some other onions are worse, and burn our eyes badly. Why?
Answers:
Onions contain the chemical sulfur, as well as enzymes that speed up chemical reactions. The sulfur and the enzymes rest on opposite sides of the onions’ cell walls-until they are cut open. Then the sulfur and enzymes come in contact and start a chain of chemical reactions. New molecules float up in the air and react with the nerve cell membrane of the eye to form sulfuric acid and cause tearing. While you can’t see these reactions, you can feel the results when your eyes start to burn and water.
To prevent tearing, chill onions for about 30 minutes before
cutting them. The chemical reaction will be slowed down by the lower temperature. Another strategy to try is cutting the onion with a sharp knife. When you do this, less damage will occur to the onion’s cells and fewer of the tear-producing compounds will be released. Finally, be sure to cut the root end of the onion last, as it contains the largest concentration of the sulfuric compounds. For more information about onions, visit www.onions-usa.org.
It is caused by a chemical that is secreted within the onion's cells. When you cut the onion, you crush a lot of these cells and the chemical is released.
The biological purpose of this (and most of the stuff in plants) is to keep insects and animals away from the bulb and leaves. Stinging nettles sting any animal that tries to eat them, for example. Nature never counted on the nettle eating contests though!
Edit: This is also the reason why tomato and rhubarb leaves are poisonous. Cucumber and Celery are also toxic to some degree, as is chocolate, hot peppers, coffee, and limes. Sage and Coffee are excellent natural herbicides.
The technical name is "syn-propanethial-S-oxide."
Sulfur and enzymes
its the odor given of by the onion..
red onions are the worst in my opinion.
good question
becuz onions send up a vapor type thing and it stings ur eyes which causes u 2 have a runny nose
I really don't know, but, if you run it under cold water for one minute, it won't make you cry nor will it burn your eyes.
Suggestion: If you run your onion under cold water while you cut it, it will take away those symptoms.
They dont make me cry - I have dry eyes -sjogrens syndrome - and they dont affect me at all!
As onions are sliced, cells are broken, allowing enzymes called alliinases to break down sulfides and generate sulfenic acids (amino acid sulfoxides). Sulphenic acids are unstable and decompose into a volatile gas called syn-propanethial-S-oxide. The gas dissipates through the air and eventually reaches the eye, where it reacts with the water to form a dilute solution of sulfuric acid. This acid irritates the nerve endings in the eye, making them sting. Tear glands produce tears to dilute and flush out the irritant.