Why Do So Many People Cry When Using Onions?

[Bartmanhomer]

I always wonder why so many people cry when using onions? It always a mystery to me how can vegetables made people cry. Why is that actually?

[tomandtish]

Becayse cutting onions releases syn-propanethial-S-oxide, which irritates your eyes.

The process goes as follows:

Lachrymatory-factor synthase is released into the air when we cut an onion.
The synthase enzyme converts the amino acids sulfoxides of the onion into sulfenic acid.
The unstable sulfenic acid rearranges itself into syn-ropanethial-S-oxide.
Syn-propanethial-S-oxide gets into the air and comes in contact with our eyes. The lachrymal glands become irritated and produces the tears!

[Kaptin Keen]

Becayse cutting onions releases syn-propanethial-S-oxide, which irritates your eyes.

The process goes as follows:

Lachrymatory-factor synthase is released into the air when we cut an onion.
The synthase enzyme converts the amino acids sulfoxides of the onion into sulfenic acid.
The unstable sulfenic acid rearranges itself into syn-ropanethial-S-oxide.
Syn-propanethial-S-oxide gets into the air and comes in contact with our eyes. The lachrymal glands become irritated and produces the tears!

I saw a very detailed description once of how the sinner is the spongy bit of the onion, in the center just above the root. It explained how to cut this bit out, throw it away, and now you can cut the rest of the onion without tears. Hooray!

It does not work that way. I've tested this extensively (I have sensitive eyes, apparently), and the guy who made that video was full of it.

Or I'm doing it wrong. That could also be the case.

[Wardog]

I remember onions making me cry as a child, but they haven't done so in years. Except a few years ago I was on holiday in Australia (I live in the UK normally), and the onions there really made me cry.

So presumably there is a difference depending on the breed or variety of onion, and I guess that some years back there must have been a change in what is the commonly-sold variety in the UK.

[Peelee]

I saw a very detailed description once of how the sinner is the spongy bit of the onion, in the center just above the root. It explained how to cut this bit out, throw it away, and now you can cut the rest of the onion without tears. Hooray!

It does not work that way. I've tested this extensively (I have sensitive eyes, apparently), and the guy who made that video was full of it.

Or I'm doing it wrong. That could also be the case.

If you have a glasstop, move the cutting board to the range and turn on the fume hood. If it doesn't completely remove the irritation (it does for me), it will at least significantly reduce it.

Obviously this works best when not using the range at the time and still in the prep stage.

[factotum]

Isn't having bread nearby the onion supposed to absorb the nasty chemicals and prevent the tears? Sure I remember reading that somewhere.

[tyckspoon]

Isn't having bread nearby the onion supposed to absorb the nasty chemicals and prevent the tears? Sure I remember reading that somewhere.

There's probably as many 'tricks' for reducing onion tears as there are kitchens that use onions - the one I was told is to stick your tongue out. Theory is the offending gasses will bind with the water in your saliva and reduce the amount that makes it up to your eyes. (A similar one holds that rinsing the cut surface of the onion should help.)

I suspect the only ones that actually work are 1: Wear goggles and 2: Get better with your knife skills and cutting technique to minimize the amount of time you have to interact with the onion once you start cutting into it. Possibly 'take your cut onions away from your workspace and let them finish gassing out somewhere other than where you are as soon as possible', too, especially if you have several onions to work through - having a large pile of chopped onion sitting on the side of your cutting board while you start the other ones is not helpful.

[Peelee]

There's probably as many 'tricks' for reducing onion tears as there are kitchens that use onions [snip]

I suspect the only ones that actually work are 1: Wear goggles and 2: Get better with your knife skills and cutting technique to minimize the amount of time you have to interact with the onion once you start cutting into it.

I suspect your list is only two items because you haven't used the fume hood method.

It's very similar to how the goggles work; if the fumes don't hit you, they don't bother you.

[Bartmanhomer]

Becayse cutting onions releases syn-propanethial-S-oxide, which irritates your eyes.

The process goes as follows:

Lachrymatory-factor synthase is released into the air when we cut an onion.
The synthase enzyme converts the amino acids sulfoxides of the onion into sulfenic acid.
The unstable sulfenic acid rearranges itself into syn-ropanethial-S-oxide.
Syn-propanethial-S-oxide gets into the air and comes in contact with our eyes. The lachrymal glands become irritated and produces the tears!

Syn-popo...what?

[Peelee]

Syn-popo...what?

It's a chemical.

[Bartmanhomer]

It's a chemical.

Ok...but the words is very scientific and it's very hard to pronounce.

[Rogar Demonblud]

Organic chemistry.

My preferred method for cutting onions is to freeze them first, then let the cut onion thaw under the range hood while I prep the rest of the ingredients.

[Peelee]

Ok...but the words is very scientific and it's very hard to pronounce.

The words are based on ACS IUPAC naming conventions. It's not too difficult to pronounce after enough practice, which comes with studying chemistry. The names aren't designed to be easy to pronounce for any given person, they're designed to let people know what the molecule looks like.

[Knaight]

On onion cutting tricks - the one I've found that works (besides knife sharpness) is to cut the onions while they're submerged. It's hard for volatile chemicals to aerosolize when they'd have to go through water first, especially when they're reasonably polar. Which a thiol is. I usually don't bother and just cut through the tears, but if I'm going to cut a dozen onions at once or some nonsense? Out comes a mixing bowl full of water.

The words are based on ACS naming conventions. It's not too difficult to pronounce after enough practice, which comes with studying chemistry. The names aren't designed to be easy to pronounce for any given person, they're designed to let people know what the molecule looks like.

That's not ACS - it's IUPAC. It's also an example of a really easy to pronounce word by IUPAC standards.

[Peelee]

The words are based on ACS naming conventions. It's not too difficult to pronounce after enough practice, which comes with studying chemistry. The names aren't designed to be easy to pronounce for any given person, they're designed to let people know what the molecule looks like.

Blah, it's been a while since organic. But I can still draw a mean hexagon!

[Bartmanhomer]

The words are based on ACS IUPAC naming conventions. It's not too difficult to pronounce after enough practice, which comes with studying chemistry. The names aren't designed to be easy to pronounce for any given person, they're designed to let people know what the molecule looks like.

What IUPAC stands for.

[halfeye]

I'm fairly sure that weeks and months of exposure hardens you against the effect, so not having cut any for years I'd be crying all over the place if I did it now, I'm also pretty sure that some varieties of onions are stronger than others and will make people cry more than the same people would with other milder varieties.

[Peelee]

What IUPAC stands for.

International Union of Pure and Applied Chemistry

[Knaight]

What IUPAC stands for.

International Union of Pure and Applied Chemistry.

[Bartmanhomer]

International Union of Pure and Applied Chemistry

International Union of Pure and Applied Chemistry.

Thank you both. LOL!

[Knaight]

Blah, it's been a while since organic. But I can still draw a mean hexagon!

How are your chair diagrams, for those terrible terrible hexagons which don't have the decency to toss in 3 double bonds?

[Peelee]

How are your chair diagrams, for those terrible terrible hexagons which don't have the decency to toss in 3 double bonds?

I choose to believe my professor disregarded my obvious talent as the herald of Cubism in molecular diagram design, to the detriment of the scientific world.

[snowblizz]

International Union of Pure and Applied Chemistry

Is there a union for the impure and unapplied chemistry?

[Kaptin Keen]

Is there a union for the impure and unapplied chemistry?

It's more of a confederacy :p

[snowblizz]

It's more of a confederacy :p

Sounds about right.


Forgot to mention I've heard about having a piece of crispbread (knäckebröd) in your mouth, just to add to the pile of "no but serisouly isn't the crying possibly better than looking like an idiot" pile of "solutions". I can't remember if it worked, I do remmeber you end up drooling like Basset hound when you try it.
I guess that kinda combines the absorbant bread with shielding face theories.

[Razade]

Becayse cutting onions releases syn-propanethial-S-oxide, which irritates your eyes.

The process goes as follows:

Lachrymatory-factor synthase is released into the air when we cut an onion.
The synthase enzyme converts the amino acids sulfoxides of the onion into sulfenic acid.
The unstable sulfenic acid rearranges itself into syn-ropanethial-S-oxide.
Syn-propanethial-S-oxide gets into the air and comes in contact with our eyes. The lachrymal glands become irritated and produces the tears!

Specifically it's when the cell walls break. Sharp knives will mitigate this more than any "life hack" you'll find short of wearing goggles. Which I know plenty of people do in the food industry. My job has two pair for people who have to cut onions all day.

[Peelee]

It's more of a confederacy :p

Got a laugh out of me.

Specifically it's when the cell walls break. Sharp knives will mitigate this more than any "life hack" you'll find short of wearing goggles.

This does not at all detract from your point, but the sharpest blade I have is on my meat slicer, which makes me cry the most when cutting onions. Of course, this is due entirely to me using it when I want paper-thin slices, so I'm slicing a single onion way more than any sane person normally would.

I also don't know why I call it a meat slicer when it's an everything-slicer.

[Strigon]

...

I also don't know why I call it a meat slicer when it's an everything-slicer.

Clearly you're just being loose with your definition of meat. Coconuts have meat, so why not onions? Carrots? Celery?

[Lord Torath]

Is there a union for the impure and unapplied chemistry?

Yes. It's the International Union of Pure and Applied Chemistry.

Un-applied Chemistry is Pure Chemistry, and Applied Chemistry is Impure Chemistry.

[Brother Oni]

I'm fairly sure that weeks and months of exposure hardens you against the effect, so not having cut any for years I'd be crying all over the place if I did it now, I'm also pretty sure that some varieties of onions are stronger than others and will make people cry more than the same people would with other milder varieties.

As someone who spent years working in a kitchen, you can build up a tolerance to cutting onions, much like you can build up a tolerance to tear gas and pepper spray.

I can also recommend not standing directly over the onions while you cut them and having a breeze of some sort to blow the fumes away (similar to the fumehood method, only without an additional physical barrier and extraction).