Why people cry when they cut onions: a scientific explanation

Chopping onions is a fairly mundane, familiar task that can turn into a real drama. The pungent odor and burning sensation in the eyes make even the most brutal men cry.

The question of why onions make us cry has been bothering people for a long time. That's why IFL Science shared a scientific, but rather simple explanation.

Tears

Tears are not just a liquid flowing from the eyes. It is a complex biological system that performs important functions for our health.

To begin with, it is worth noting that people have several types of tears:

Basal tears are secreted constantly, moisturizing the eyes, washing away dust and dirt, and protecting them from infections;

Emotional - released in response to strong emotions, such as joy, sadness, anger, or pain;

Reflex - released in response to stimuli such as smoke, dust, wind, or chemicals.

In this case, we are talking about reflex tears, because they are released when people are exposed to allergens, dust, or chopping onions.

What's wrong with onions?

An onion is not a plant, but a bulb of a perennial plant, so its natural goal is to survive underground as long as possible. Many insects and animals live underground, looking for something to eat every day. Therefore, the bulbs have learned to protect themselves through chemical reactions.

When the structure of onions is damaged, for example during slicing, certain chemical processes begin to occur, such as the release of an amino acid called S-1-propenyl-L-cysteine sulfoxide.

This substance begins to react with other elements, resulting in the formation of thiopropanol-S-oxide, which reacts with water molecules to form sulfuric acid.

This acid is considered one of the most aggressive and chemically active reagents. Fortunately, its concentration when slicing onions is too low to harm us, but enough to make us cry.

How not to cry when slicing onions

You probably already know that most of the life hacks that are supposed to save you from crying while cutting onions don't work. But if we look at the situation from a chemical point of view, we can conclude that the molecule that causes tearing is highly soluble in water and it is quite easy for it to turn into a gaseous state.

Therefore, there are three tips that will allow us to cry less while cooking:

• Cool the onion before chopping;
• Turn on the hood while slicing;
• Chop onions under water.

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