What can I do to avoid crying when cutting onions? Experts give tips

Do you need to cry? Time to chop an onion.

Onions are tasty and an essential part of many dishes, but the burning sensation in your eyes can make them not seem worth it.

Everyone claims to have the best trick for reducing tears when cutting onions, but the CNN spoke to experts to see which ones are worth it.

Why do I cry when cutting onions?

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

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

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

When you damage these cells — like with a knife — an enzyme and an amino acid combine to form sulfur compounds and another enzyme that sends vapor into the air and eventually into your eyes, said Dr. Bryan Quoc Le, research faculty from 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 tears,” Thiel said in an email.

Use a fan

A great method to produce fewer tears when cutting onions is place a fan near you to blow the air near the vegetable away Thiel said.

“This way, the wind blows away the molecules that usually get into your eyes and lead to tears,” she said.

Protect your eyes with protective glasses

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

“I noticed that wearing contact lenses (instead of glasses) makes a big difference when I'm chopping an onion,” Thiel said. “You just want to have some kind of shield protecting your eyes.”

Cool the onion

The refrigerator, freezer or a bowl of ice water can also help, Le said.

Freezing, like microwaving, can change the texture of the onion, so only use this method when you're making something like soup. he said.

And storing onions in the refrigerator can diminish their flavor, Le said. Instead, keep your onions in a cool, dry place and place them in the refrigerator or in cold water about 20 minutes before you start chopping, he said.

Turn up the heat

Heat can help reduce fumes, so you can heat an onion in the microwave 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're making something where the texture of the onion isn't as important, because using the microwave can interfere with the crispiness of the onion.

Add acids

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

The enzyme that converts amino acids in onions to cause the burning sensation works well in a specific pH range, he said. An acid like lemon or vinegar will slow the enzyme, producing the vapors that lead to tears.

Decreasing the onion's tear-inducing enzyme has another advantage: It keeps intact the amino acid that gives onions its ability to enhance flavor in a recipe, Le said.

Light candles

Some people swear that lighting a candle while chopping an onion works. It's possible this could work, Le said.

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

But it's not a guaranteed method, he added.

“Maybe it will distract you from the pleasant smell,” Thiel said.

Bite a piece of bread

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

Some people may find this method reduces burning sensation and tears, but it's not something that can be counted on to work every time, he said.

Le said he's not sure about the theory behind it. It could be the bread absorbing the steam, or it could be psychological, he said.