How does onion burn our eyes while we are cutting it? The answer is interesting. There are two kinds of enzyme in onion. The first named as alliances and second as lachrimatory factor synthase (LSF). There is also an acid called as amino acid sulfoxides. While we cut the onion we break the cells of onion. The enzymes and acids that were kept separate inside the cells begin to mix up with each other. The first enzyme helps to convert amino acid sulfoxides into sulfenic acids. Then LSF treats with sulfenic acid to produce Syn-propanethial-S-Oxide. This reaches to our eyes and reacts with the waters or moistures present in our eyes. This interaction produces sulfuric acid which produces a burning sensation in our eyes and this signal is carried up to brain through a sensory neuron called as ciliary nerve. Then brain again signals lachrymal gland to produce tears in a huge amount so that the acid will go out and the irritation would stop.

There are many ways to stop our eyes from being irritated while cutting onions………They are…..

(a) Before cutting the onions cut it into two or four halves and dip inside water for some time. The enzymes of onions are water soluble so, they dissolve in water. This will prevent the reaction between enzymes and acids which will prevent our eyes from burning and being watery.

(b) Use sharp knife to cut onions. Enzymes are released when we cut them by breaking their cells. This will apply more pressure (since the area will be small) so the cells will be sliced rather than being crushed down and spreading which will stop mixing of chemicals and so on.

(c) Chop the onion very fast. Due to inertia the enzymes and cells remain at the same position which prevents the mixing of enzymes and acid. It will occur so fast that the gas will not get too much chance to touch our eyes.

(d) Put the onion in freezer for some time before you cut onions. The enzymes will freeze so there is less chance of mixing of acid and enzyme.

(e) Burning candle around where you cut onion is also a way because the acid emitted will go towards flame although it is not much effective all the time.

(f) Wearing swimming goggles prevents the acid from going towards your eyes and you will not find it burning. This is the most effective way.

(g) Use fan during you cut onions. This will blow the acid away.

(h) Sing a song or simply blow air from your mouth while cutting onion. This will also blow the acid away.

(i) Spray some water in your chopping board and cut the onions. The mechanism works as the first on.

(j) Cut the root at last because you will find more acid over there which is enough to burn your eye badly.

(k) Cut more onion as you can. This will develop your eye in such a way that it will find its way to protect against the acid.

(l) If you have a clean cloth then make it wet with water and cut onion above that surface.

(m) If you have practice you can close your eyes and cut the onion.

There is also another device that you can make in your home if you don’t have swimming goggles………I created it like this………..



Take a box like this.


Cut its three sides from middle in this way.



Paste a hard and transparent plastic in it.


You can keep it like this.



Decorate it if you want.



Put elastic as shown above.


Cover it from back side and put button on one end side of it.

 Note: You have to bend a little bit while cutting this so that that will be comfortable for you.
Discovered by Kapil Sharma via Don Prince