Why Do Onions Make You Cry?
Cutting onions often leads to tears, but not because you’re feeling emotional—it’s pure science. So, why do onions make you cry?
The Science Behind the Tears
When you slice into an onion, you damage its cells. This releases an enzyme called alliinase. The enzyme reacts with the sulfur-containing compounds in the onion, forming a gas known as syn-Propanethial-S-oxide.
As this gas wafts up into the air, it reaches your eyes. Your eyes detect it as an irritant, triggering a defensive response: they start to produce tears to flush the substance out.
Why Does It Hurt So Much?
The gas interacts with the moisture in your eyes, forming a mild sulfuric acid. It’s this acid that causes that familiar burning sensation, forcing you to blink or tear up—sometimes dramatically.
Can You Stop It from Happening?
Yes, there are a few tricks!
- Chill the onion in the fridge before cutting—it slows down the enzyme reaction.
- Cut near running water or under a vent to help carry the gas away.
- Use a sharp knife to reduce cell damage and minimize gas release.
Final Thought
It’s not your fault you cry when chopping onions—it’s clever chemistry at work. So next time you tear up, know it’s just science saying hello!