Why do we cry when we chop the onion?

2000/03/08 Elhuyar Zientzia

• Anatomia/Fisiologia

Sulfur is responsible for the bitter taste of onion. Onions are used as protection for sulfur substances. By decreasing the onion, sulfur gases (SO3) are evaporated, derived from sulfur substances for protection. Gas reaches the eyes and, in contact with eye water, becomes sulfuric acid, which is an irritating acid.

At the same time, to neutralize the action of acid, the eye gives off tears, one of the mechanisms of protection of the eye, is crying.

To avoid crying, we often use tricks or remedies, and one of them is to put us in the refrigerator 10 minutes before we chop the onion, as they have shown us that the cold onion causes less crying. Why? The cold produces a greater evaporation of sulfur gases, which reduces the generation of sulfuric acid.