Onions and tears

When I cut onions, I sometimes get tears in my eyes.

When the onion cells are crushed, an enzyme (alinase) released from the cells reacts with the sulfoxide to produce sulfenic acid.
This stabilizes to form a sulfuric acid gas (syn-propanethial-S-oxide), which reacts with water to generate sulfuric acid.
Then the eyes become irritated and tears flow to wash away the sulfuric acid.

Use a sharpened knife (use a good technique)
Sharpened knives reduce the amount of gas produced by breaking down fewer cells. (Those who are good at cooking will destroy less cells with the same knife.)

Let the onions cool.
Since enzymatic reactions and volatilization reactions are temperature dependent, refrigerating for 1-2 hours reduces the amount of sulfenic acid produced.
*In general, onions are not suitable for storing in the refrigerator, so cool them before cutting.

Heat the onion in the microwave.
Sulfuric acid gas changes to sweet component

Prevent gas from entering your eyes.
Work in a well-ventilated area. turn the ventilation fan. such as wearing goggles.

Another method is to wet the knife and onions, but it is true that sulfide is water-soluble, so even a small amount of water is effective, but it is slippery and difficult to cut, and keeping the knife wet is a reality. not targeted.

These substances in onions are protective substances to protect themselves from germs and pests.