Why Do We Cry When We Cut Onions?

Why do we cry when we cut onions?

Onions are a staple ingredient in many cuisines around the world, but they can also be a source of tears. So, why do we cry when we cut onions? And are there any ways to avoid the tears?

The science of onion tears

When you cut an onion, you damage its cells. This releases enzymes that react with other compounds in the onion to produce a gas called syn-propanethial-S-oxide (SPSO). SPSO is a lachrymatory agent, which means that it irritates the eyes and causes tears.

SPSO irritates the eyes in two ways. First, it dissolves in the water that covers the surface of the eye. This creates an acidic solution that stings and irritates the eye’s tissues. Second, SPSO stimulates the trigeminal nerve, which is responsible for sending sensory information from the face to the brain. The trigeminal nerve tells the brain that the eye is irritated, and the brain responds by sending signals to the tear glands to produce tears.

Why do onions produce SPSO?

Onions produce SPSO as a defense mechanism against predators. When an animal bites into an onion, the SPSO gas irritates its eyes and mouth, making it less likely to eat the onion.

How to avoid crying when you cut onions

There are a few things you can do to avoid crying when you cut onions:

• Use a sharp knife. A sharp knife will cut through the onion cells more cleanly, releasing less SPSO gas.
• Cut the onion under running water. The water will help to dissolve the SPSO gas before it reaches your eyes.
• Chill the onion before cutting it. This will slow down the enzymatic reactions that produce SPSO gas.
• Wear goggles or a swimming mask. This will protect your eyes from the SPSO gas.

Here are some fun facts about onion tears:

• Not everyone cries when they cut onions. Some people are more sensitive to SPSO gas than others.
• Onions with a higher sulfur content produce more SPSO gas and are more likely to make you cry.
• Cooking onions destroys the enzymes that produce SPSO gas, so you won’t cry when you cook onions.
• There is a type of onion called the “tearless onion” that produces less SPSO gas and is less likely to make you cry.

Conclusion

So, there you have it. The science behind crying from onions. Next time you’re cutting onions, try one of the tips above to avoid crying. But if you do end up crying, don’t worry, it’s just a natural defense mechanism. And remember, tears are a sign of strong eyes!