Why does our eyes tears when we cut onions?

Question

Why does our eyes tears when we cut onions?

Answer 1

When you slice through an onion, you break open a number of onion cells. Some of these cells have enzymes inside of them, and when they are sliced open, the enzymes escape. The enzymes then decompose some of the other substances that have escaped from sliced cells. Some of these substances, amino acid sulfoxides, form sulfenic acids, which then quickly rearrange themselves into a volatile gas.

The gas reaches your eyes and reacts with the water that keeps them moist. This changes the chemical's form again, producing, among other things, a mild sulfuric acid, which irritates the eyes. The nerve endings in your eyes are very sensitive and so they pick up on this irritation (this is why our eyes sting when we slice onions). The brain reacts by telling your tear ducts to produce more water, to dilute the irritating acid so the eyes are protected. Your other reaction is probably to rub your eyes, but this will actually make the irritation a lot worse, of course, if you have onion juices all over your hands.

Answer 2

When you cut an onion your eyes start burn and makes you tear up uncontrollably. What is it in onions that make them such an ordeal to prepare?

When you cut or slice an onion, you break open a number of onion cells. Some of these cells have enzymes inside, and when they are sliced open, the enzymes escape. The enzymes then decompose some of the other substances that have escaped from sliced cells. Some of these substances, amino acid sulfoxides, form sulfenic acids, which then quickly rearrange themselves into a volatile gas. When theses gases reach your eyes and reacts with the water that keeps them moist. This changes the chemical's form again, a mild sulfuric acid, which irritates the eyes. The nerve endings in your eyes are very sensitive and so they pick up on this irritation. The brain reacts by telling your tear ducts to produce more water, to dilute the irritating acid so the eyes are protected. Your should not rub your eyes at this stage and just wash it with cold water to stops tears come out. It will talk atleast 10 – 15 minutes to become normal. -

Answer 3

Inside the onion cells there are some chemical compounds which contain sulphur. When you cut an onion its cells are broken and those chemical compounds then undergo a reaction that transforms them into a more volatile sulphured products, which are released into the air. These sulphured compounds react with the moisture in your eyes forming sulphuric acid, which produces a burning sensation. The nerve endings in your eyes are very sensitive and so they pick up on this irritation. The brain reacts by telling your tear ducts to produce more water, to dilute the irritating acid. So you cry to keep your eyes protected from the acid. There are some tricks to make onion-dicing less problematic: - Chop the onion under cold water. The volatile sulphured compounds will be released but then they react with the water, instead of reaching your eyes. - You can freeze the onion for 10 minutes before cutting it. The cold temperature of the onion will slow down the chemical reaction which forms the volatile sulphured compounds. Hope this helps Good luck

Answer 4

tears come out for three reasons !!!!!

first reason: in case of contamination, if someone for example spat on your eye (that is a harsh example), ull eye will automatically release tears as they have an antiseptic effect.

second reason: in case of foreign contact: if u stick a pencil in your eye (and thats another harsh example), the tears will come out to get rid of it (as it will lubricate the eye, making it esier to remove)

the third reason: [which is very complex - not quite understood] due to emotion, when u sad/happy etc its a refelx neurological reaction.

ur case of onions will be a mix of the first 2 (and of the third - if u extremely enjoying chopping onions)..

this is because the vapours released from onions when cut will trigger the first 2 mechanisms. so, first tears will clean the eye and second, tears will try to get rid or anything in it!

Answer 5

As the knife compresses and cuts the onion, it sends micro-droplets of onion juice into the air which contain sulphur and other irritants. As we breathe and the juice lands in our eyes and sinuses, misery.

Answer 6

The onion releases sulfur when you cut it and the gas burns your eyes

Answer 7

I'm sure someone else will answer the question scientifically but all I can do is propose a solution. I have a pair of skiing goggles hanging in my kitchen... no more tears!