why do onions make your eyes sting

Question: Why Do Onions Make You Cry? Answer: Unless you ve avoided cooking, you ve probably cut up an onion and experienced the burning and tearing you get from the vapors. When you cut an onion, you break cells, releasing their contents. Amino acid sulfoxides form sulfenic acids. Enzymes that were kept separate now are free to mix with the sulfenic acids to produce propanethiol S-oxide, a volatile sulfur compound that wafts upward toward your eyes. This gas reacts with the water in your tears to form. The sulfuric acid burns, stimulating your eyes to release more tears to wash the irritant away.


Cooking the onion inactivates the enzyme, so while the smell of cooked onions may be strong, it doesn t burn your eyes. Aside
goggles or running a fan, you can keep from crying by refrigerating your onion before cutting it (slows reactions and changes the chemistry inside the onion) or by cutting the onion under water. See Also: The sulfur-containing compounds also leave a characteristic odor on your fingers. You may be able to remove or reduce some of the smell by wiping your fingers on a. Your mother asks you to chop some onions and the mere thought of it can literally make you cry.


Have you ever wondered why do onions bring tears to our eyes when we cut them? We will tell you why. Everyday Chemistry - Why do onions make us cry? The mere thought of chopping onions can literally make you cry. But the moment your knife touches the onion, your eyes start burning and you have tears in your eyes. Heres why it happens. What do onions contain? Onions contain amino acid sulfoxides that form sulfenic acids in the onion cells. Both the enzymes and the sulfenic acids are kept separately in the cells. When you cut the onion, the otherwise separate enzymes start mixing and produce propanethiol S-oxide, which is a volatile sulphur compound that starts wafting towards your eyes.


The gas that is emitted reacts with the water of your eyes and forms sulphuric acid. The sulphuric acid thus produced causes burning sensation in your eyes and this in turn leads to the tear glands secreting tears. Thus you end up with watery eyes every time you cut onions at home. It is the sulphur compound in the onions that also leave a typical odour of onions on your hands and utensils even after washing. Tips to avoid the tears: Make sure that you keep your fans off while cutting onions.


If it is running, the air is on constant circulation, which will lead to the spread of gas and increase the burning sensation in your eyes. Refrigerate the onion before cutting. By refrigerating, you freeze the enzymes from mixing with the sulfenic acids and the production of propanethiol S-oxide is stopped. As a result, sulphuric acid is not formed when you chop the onions. Wear safety goggles while chopping onions. It is also a good idea to keep away the gas from reaching your eyes. Cooking the onion inactivates the enzyme. So cook the onion after you de-skin and before letting the knife touch the onion.


Soak onions in water before cutting. Water absorbs the gas and you can avoid the tears. Lighting a candle or a lamp near the chopping board is another effective way to avoid the tears. When a candle is lit near the chopping board the gas that is emitted from the onions get drawn towards the flame of the burning candle or lamp and it does not reach your eyes Avoid cutting the onion till the root. This will prevent the mixing of enzymes with the sulfenic acids and you can spare your eyes of the burning sensation and tears.