Why tears come while cutting an onion?

Tears come while cutting an onion because onions release a chemical called syn-Propanethial-S-oxide that irritates our eyes. When an onion is cut, its cells break and release enzymes. These enzymes react with sulfur compounds in the onion to form a gas. This gas reaches our eyes, where it reacts with water in the eyes to form a mild acid. The acid irritates the eyes, and the tear glands produce more tears to wash it away.

Steps of Onion Causing Tears

1. Cutting onion breaks its cells.
2. Enzyme alliinase is released.
3. Gas syn-Propanethial-S-oxide is formed.
4. Gas reaches eyes and forms acid.
5. Tears come out to wash away irritation.

Tips to Avoid Onion Tears

• Cut onions under running water.
• Refrigerate onions before cutting.
• Use sharp knives to reduce cell damage.