Why Do Onions Make People Cry While Chopping And Cutting Them

Onions are a staple in many kitchens, adding flavor to countless dishes. 

But there's one thing many people cooking in the kitchen dread, the inevitable tears that come with chopping them. 

Unlike sad movies, this reaction is pure science. Here's the surprising story behind why onions make you cry.

Nature's Fly Swatter:

Onions, like many plants, have built-in defenses against hungry insects. 

They contain special chemicals that act like a natural bug repellent. These chemicals are kept separate inside the onion's cells until you cut or chop it.

The Reaction Chain:

When you break open an onion cell, two things happen. Enzymes, which are like tiny molecular machines, get released. 

Then, the onion's sulfur-containing compounds come into contact with the air. These enzymes react with the sulfur compounds, creating a gas called syn-propanethial-S-oxide.

Tears To The Rescue:

Syn-propanethial-S-oxide is a volatile gas, meaning it easily travels through the air. 

This gas floats right up to your eyes, where it bumps into the water layer that keeps them moist. 

Here's the key part: syn-propanethial-S-oxide reacts with the water, creating a weak form of sulfuric acid (much milder than the acid used in car batteries).

This weak acid irritates the sensitive tissues around your eyes. 

Your body's clever defense mechanism kicks in, triggering your tear ducts to flush out the irritant. 

The tears wash away the syn-propanethial-S-oxide, soothing your eyes and preventing any damage.

Beating The Cry:

So next time you're chopping onions, remember, it's not sadness, it's science. Here are a few tricks to minimize the tears:

• Sharper is better: A sharp knife damages fewer cells, reducing the amount of irritating gas released.
  

• Chilling helps: Cold temperatures slow down the enzyme activity. Try chilling your onion in the fridge for 30 minutes before chopping.

• Water is your friend: Run cold water over the onion while chopping, or place a bowl of water nearby to trap the gas.

• Sweet mercy: Certain onion varieties, like sweet onions, have lower levels of the tear-inducing chemicals.
  

By understanding the science behind onion tears, you can take steps to prevent them and keep your eyes watering for joy, not frustration.