A scientific journal reveals the reason for “revenge tears” when cutting onions and offers solutions

Onions are one of the best foodstuffs that may add a delicious taste to meals, whether they are grilled, fried, cooked, or in their natural state as well, in addition to that they include many nutritional benefits for the human body.
And as always, every beautiful has a price in life, which is what happens when we prepare a dish containing onions, where this plant directs its only defense against those who try to cut it and eat it, and forces everyone to cry before facing its inevitable end, but how can he do that?
The “weapon of revenge” is a compound that forms after slicing
Scientists call this “culprit”, if correct, the tear factor, which is a chemical that severely irritates the eye.
Onions in their natural state (uncut) contain two separate compounds: “Cysteine ​​sulfoxides”, and an enzyme called “alinase”, but when onions are cut into slices or cubes or crushed, the barrier separating these two compounds breaks, and the two meet together, which leads to a reaction, and the allinase enzyme causes the conversion of “cysteine ​​sulfoxides” to sulfonic acid, a sulfur compound.
“Sulfuric acids have two options,” said Josie Silveraroli, Pharm.D. from Ohio State University and first author of a 2017 study published in the Journal of the American Chemical Society “CS Chemical Biology,” about the lacrimal factor in onions: “Sulfuric acids have two options. The first is that they can condense spontaneously. It reacts within itself, and becomes an organosulfur compound. It is the organosulfur compounds that give onions their strong smell and flavour, and there is a similar action that occurs in garlic, which is why it has a pungent flavor.”

“But the second choice of sulfonic acid is unique to onions and another pair of alliums (a genus of plants), or a genus of flowering plants that produce vegetables like onions, garlic, green onions and leeks. There is another enzyme, called tear factor synthase, which hides in the cell and plays its role. It rearranges the sulfonic acid in the lacrimal factor.

“The tear agent is a volatile liquid, which means it turns into a vapor very quickly,” Silveroli said. “That’s how it gets to your eyes and irritates the sensory nerves, and the eye begins to secrete tears to get rid of the irritants.”
Tips to reduce the severity of the problem

It is recommended to wear protective glasses or lenses when cutting onions, or anything that can form a barrier between the onion and the face… In addition, a sharp knife contributes to damaging a small number of cells, which reduces the secretion of this compound significantly and alleviates the problem.
“Live Science” scientific journal
It is possible that both the organosulfur compounds that give onions their intense flavor and the tear factor have evolved as defense mechanisms in these plants, the purpose of which is to stop insects, animals or parasites that may harm the plant, Silveroli said in statements to the scientific journal “Live Science”. onions.