I was helping my mom in the kitchen today, and when I started chopping onions, my eyes started stinging and tearing up. But then I realized something weird – when we eat onions in our food, they don’t make us cry at all!Can someone explain why onions make us cry when we cut them
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It’s because when cut, the onion releases a gaz. That gaz when it makes contact with the moisture in your eyes creates a reaction which causes you to tear as it irritates your eyes.
When it’s cut in your food, that gaz has already dissipated
Due to onion juice fumes. The more juice comes out, the more fumes. If you cut onions with a really sharp knife, you will cry less. Alternatively, if you cover eyes with protective glasses, you will not cry.
Edit: I felt like I didn’t finish explaining to a 5yo.
Fumes are slightly corrosive/damaging to weak tissue and it attacks your eyeballs. Your eyeballs trigger tear glands to squeeze water to dilute corrosion. Therefore you cry.
When eating salad or any dish with fresh onions, onion juice by that time has already evaporated. The rest of juice is contained in the onion pieces, but since you are eating it, it doesn’t fume so much and your eyes have no direct contact with fumes.
When you cut an onion, you’re breaking open its cells. These cells contain a secret weapon – a chemical that turns into a gas when it meets the air. This gas is like an invisible, irritating cloud that floats up to your eyes.
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Because onions emit vapours when you cut them, which is what stings your eyes. This doesn’t happen when eating onion in food, unless you take a raw onion and ate it like an apple, then it would sting your eyes.
Ok the compound in onions, sulfur among them, are released when you cut the cells. The sulfur becomes a gas and floats upward. The sulfur interacts with the water in your eyes and creates a weak solution of sulfuric acid.
It’s literally sulfuric acid in your eyes.
When you cut an onion with a knife that isn’t very sharp… you’re more like crushing it than cutting it.
The crushing makes the onion juice come out like a spray that fills the air, and then it gets in your eyes that way.
A very sharp knife will cut down on eye burning by a lot.
Onions just sitting there, or being chewed don’t have that happening.. especially if it’s contained within your mouth.
The tears are caused by a chemical that is produced by the onion’s defence mechanism. When an onion is cut, enzymes are released from ruptured cells which catalyze chemical reactions which eventually forms a compound called *syn-Propanethial S-oxide*, which is a lachrymator (tear agent). This liquid readily evaporates into gas and the vapors irritate the tear glands in your eyss and cause you to tear up.
Contrary to popular belief this has nothing to do with sulfuric acid, so any answers that purport this myth can be mostly disregarded.
If the onion is cooked, the high temperature *denatures* the enzymes and inactivates them, so you’re not going to have the conditions required to form that tear gas anymore. And any of that S-oxide from cut onions would have evaporated or boiled off in the cooking process, leaving your cooked onions free of the tear agent.
If you’re consuming the onion raw, then having it in your mouth physically prevents some of the tear agent vapors from reaching your eyes once it’s in your mouth, but of course the act of *biting* the onion is basically cutting them and will cause the tear agent to be formed. From inside your mouth, some of the tear agent can still make it to your eyes through your sinuses, so you will probably still tear up, but it might not be as bad as cutting would. This kinda depends on the exact situation.
Yeah? go eat a raw onion like an apple and report back…
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