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How not to cry while cutting onions, according to the experts

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Need a good cry? Time to chop an onion.

Onions are flavorful and an essential part of so many dishes, but that sting in your eyes may make them not feel worth it.

Everyone claims to have the best trick to cut back on tears when cutting onions, but CNN talked to experts to see which ones are worth their salt.

Why do I cry when I chop onions?

That stinging feeling in your eyes serves a purpose for onions, said Dr. Abbey Thiel, a food scientist and host of the YouTube channel Abbey the Food Scientist.

“It’s really the plant’s defense mechanism to prevent it from being eaten,” Thiel said. Many plants have ways to avoid becoming lunch, such as thorns, spines or a bitter taste, she added.

An onion’s defenses come from its cell structure, which has different compartments to separate substances that could have a reaction, she said.

When you damage those cells — such as with a knife — an enzyme and an amino acid are combined to form sulfur compounds and another enzyme that sends vapor into the air and eventually to your eyes, said Dr. Bryan Quoc Le, faculty research fellow at Pacific Lutheran University in Parkland, Washington.

“After reacting with the moisture in our eyes, small amounts of sulfuric acid are produced which irritates the cornea and leads to the tears,” Thiel said via email.

There are several effective ways to reduce stinging in the eyes and cut back on tears when chopping onions, experts say. - FG Trade/E+/Getty Images
There are several effective ways to reduce stinging in the eyes and cut back on tears when chopping onions, experts say. - FG Trade/E+/Getty Images

Use a fan

A great method for producing less tears when chopping onions is placing a fan near you to blow the air near the vegetable away, Thiel said.

“This way the wind carries away the molecules that usually enter your eye and lead to the tears,” she said.

Protect your eyes with goggles

Yes, they look dorky, but goggles are a foolproof method, Thiel said. They protect your eyes from the molecules in the air, she said.

“I’ve noticed that wearing contacts (instead of glasses) makes a big difference when I’m cutting an onion,” Thiel said. “You just want to have some type of shield protecting your eyes.”

Chill that onion

The fridge, freezer or a bowl of icy water can also help, Le said.

Freezing, like microwaving, can change the texture of the onion, so only use that method when you are making something such as a soup, he said.

And storing onions in the refrigerator can dampen their flavor, Le said. Instead, keep your onions in a cool, dry place and pop them in the refrigerator or in cold water about 20 minutes before it’s time to chop, he said.

Turn up the heat

Heat can help cut down on the vapors, so you could microwave an onion before cutting it, Le said.

Depending on the size of the onion, it should take anywhere from 30 seconds to a few minutes, he added.

But Le only recommends doing this if you are making something where the onion’s texture isn’t that important because using the microwave can interfere with the crispness of the onion.

Add acids

Acids added to your onions may help reduce the stinging in your eyes and increase the flavor for your taste buds, Le said.

The enzyme that converts amino acids in onions to cause the stinging feeling works well at a specific pH range, he said. An acid such as lemon or vinegar will slow down the enzyme making the vapors that lead to tears.

Slowing the onion’s tear-inducing enzyme has another perk: It keeps the amino acid intact that gives the onion its flavor-enhancing ability in a recipe, Le said.

Light candles

Some people swear by lighting a candle while they cut up an onion. It’s possible that doing so could work, Le said.

“I could see that working, but it really just depends on the kind of candle,” Le said. It could block the vapors, or a scented candle could have a reaction with the vapors that’s helpful.

But it isn’t a guaranteed method, he added.

“Maybe it’ll distract you with the nice-smelling odor,” Thiel said.

Bite some bread

Does it work to hold a piece of bread or toast in your mouth to avoiding crying or stop the tears? It’s hard to say, said Le, who is also the author of “150 Food Science Questions Answered.”

Some people may find that this method cuts down on the stinging, teary feeling, but it is not one you can count on to work every time, he said.

Le said he isn’t sure about the theory behind it. It could be the bread absorbing the vapor, or it could be psychological, he said.

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