Like most other plants, onion is made of cells. These cells are separated by a membrane into two sections. One side of the membrane consists of enzymes, while other side contains the molecules that consist of sulphur compound. When you cut the onion, a number of onion cells break open and the contents of both sides of membrane mix together. The enzyme causes the sulphur compound, amino acid sulfoxides to undergo a series of chemical reactions. During these reactions, sulfenic acids are formed, which are immediately converted into a volatile gas, propanethiol S-oxide. The gas reaches your eyes and reacts with the water present in the eyes. Certain chemical changes take place inside the eyes and there is formation of a mild sulfuric acid. It causes irritation of the eyes. The nerve endings in the eyes are very sensitive and hence, your eyes twinge while cutting the onion. The tear ducts in the eyes are stimulated to produce more water in order to dilute the irritating acid, so that the eyes are protected.

How To Prevent Irritation From Onion?

You can prevent irritation of the eyes while cutting onion by different ways. A simple solution is to keep your head as far away from the onion as possible. It would disperse most gas before it reaches your eyes. Another simple solution is to wear goggles, while cutting onions. However, if the kitchen is full of steam, then you may not to able to see through the goggles. If you peel the onion and chill it in the refrigerator before cutting, then it would minimize a release of gas upto some extent. A change in the temperature alters the compounds present in the onion. You can cut onions under water or run the tap over the onions as you cut it. Once you cook the onion, it causes inactivation of the enzymes. Therefore, the smell of cooked onion is strong, but not irritating to the eyes.

According to some assumptions, if you hold a piece of bread, lemon or sugar cube, it would absorb the volatile gas before it reaches your eyes and thus protects your eyes from irritation. If you breathe with your mouth instead of nose, then it might prevent a lot of gas reaching your eyes. While cutting an onion, avoid cutting its root as it consists of a higher concentration of enzymes.

By Reshma Jirage : Buzzle.com