Microarticles

Why do people's eyes water when they cut an onion?

Eyes water when you cut an onion because the highly aromatic substance allicin is produced when the sulphur-containing amino acid alliin and the enzyme alliinase come into contact. This only happens during cutting because the amino acid is normally found in the outer layer of the onion cells and the enzyme is inside the cells. The allicin then reacts with the moisture in the air. This produces a gas called propanthial sulfoxide. If it gets into the eyes, they water to protect themselves.

You can prevent this either by protecting your eyes with diving goggles or by cutting the onions under water. If you choose the latter, remember that picking up the pieces of onion can be a nuisance. However, the water prevents the propanthial sulfoxide gas from rising into the air and reaching your eyes.


Source: https://www.blickcheck.de/auge/funktion/warum-traenen-die-augen-beim-zwiebeln-sc...