Why Cutting Onions Makes You Cry?


Why cutting onions makes you cry?


When you chop an onion, you often feel a stinging sensation in your eyes, and your face uncontrollably end up with running tears. These are happening because of the chemical called syn-propanethial-S-oxide that is released by the onion that is chopped.


Peeling, cutting, or crushing an onion causes the rupture of the cells and causes them to release enzymes called alliinases. These lead to the breaking down of amino acid sulfoxide to form sulfenic acid, which reacts with lacrimatory factor synthase, an enzyme, to form a chemical called syn-propanethial-S-oxide. This chemical is volatile, that is, it can easily evaporate at room temperature and change into a gas. This gas which is eye irritant diffuses up to your eyes and creates that stinging sensation. As a result, you start blinking and crying because your eyes are trying to flush the irritant out. 


CONTENT: Deniz Güngören