The human eye forms tears, when one is cutting onions, to dilute the acid formed when sulfenic acids in gaseous form react with the water in the eyes. Sulfenic acids are formed from amino acid sulfoxides.
2 years ago
Last edited at 8:13AM on 4/28/2012
the onion has an oil that is very pungent smell and that smell affects the tear glands causing them to swell and tear up it is also used as a deterrent that is used as and called tear gas to control rioting crowds.it is also made up in thousands of chemicals not only just one.
Onions have a Brain Stem, An Onion makes you Cry, Because an Onion Contains Sulfuric Acid, This Sulfuric Acid wants to Mix with Water so It Reacts to your Eyes, The Onions Cause Discomfort to the Eyes making them Water, The Chemicals In Onions get Airborne During the Cutting and Affect Our Eyes/Sinuses, When you Cut an onion, It Releases a Gas Called Propanethiol S- oxide, When Mixed with Certain Enzymes In the Onion, It Creates a Sulfur Gas, These Gases get to your Eyes and Create a Mild Acid which Irritates the Eyes .
the cell of the onion are of two different types and when you cut them the chemicals combine to form hydrogendisulfide which them becomes airborne and combines with the water on the surface of your eye to form H2SO4 (sulfuric acid) very dilute. the tears are an attempt to raise the PH. different types of onions have varying tear forming capabilities, Vidalia onions grown with almost no sulfur in the soil very little tears, new york onions - the smallish white ones lots of tears but great for a liverwurst and onion sandwich. proper cutting can help check a cooking website.
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 sulfuric acid. The sulfuric acid burns, stimulating your eyes to release more tears to wash the irritant away