In every movie about food, thereБs a scene in which the main characterБusually an aspiring chefБends up bawling their eyes out while cutting onions. Anyone with an iota of
can relate. First the stinging, then the tearsБevery single time. Except for maybe a rare few, cutting onions always leads to some kind of cryingБwatery eyes at best, full-on tears streaming down your face like you just watched a Nicholas Sparks movie at worst. But whatБs the science behind it? Are we simply doomed to a life of painful onion encounters, or is there a way to avoid this all-too-common scenario? Turns out, there are a handful of steps you can take to reduce the tears. SELF spoke to James Chelnis, M. D. , assistant professor of ophthalmology at the Icahn School of Medicine at Mount Sinai, about why the sensation happens in the first place, and what you can do to ensure it stops. When you chop onions, they release a chemical compound that irritates your eyes and triggers your tear glands. Onions get their distinctive, pungent flavor from sulfurБthe same chemical behind rotten eggsБ stinky smell. But itБs not just the sulfur thatБs making you cry. Onions also contain an enzyme called synthase. When you cut into an onion, the synthase reacts with the sulfur to create a chemical compound called syn-Propanethial S-oxide. This compound is volatile and creates a gas that floats up to your eyes and triggers your lachrymal glandБthe gland that produces tears. And thatБs when the water works start flowing. As science-y and scary as that sounds, Dr. Chelnis says that thereБs no real danger behind the compound. БItБs just an irritant,Б he explains. You could be in a room full of people chopping onions and the worst thing that will happen to you is that you tear a lot. So as painful as cutting onions may be, youБre never going to go blind. Not everyone will react to the chemical with the same level of intensity.
Ever wonder why your friend can come away from a pile of onions mostly unscathed while youБre reduced to a puddle of tears? No, you arenБt just being extra dramatic. Dr. Chelnis explains that some people have naturally more sensitive lachrymal glands than others. Unfortunately, thereБs no way to know ahead of time if youБre extra sensitive or not, and there isnБt much you can do to change it. But there are a few hacks you can use to alleviate the pain. Try one of these three easy tricks to ward off the weeps. When an onion is cold, it doesnБt release that chemical compound as easily as it would if it were warm, says Dr. Chelnis. The next time you need to cut an onion, chill it for 10 to 15 minutes beforehand. Better yet, start Бthat way you donБt even have to factor in chill time before you get cooking. Dr. Chelnis also recommends facing a fan toward your chopping station. This will blow the gas away before it has a chance to irritate your eyes. If youБre really really sensitive to onions, and none of these tricks are, well, doing the trick, try wearing goggles. You may look a little intense, but at least you wonБt be crying. You may also like: This 200-Calorie Lentil Chili Is Actually so Delicious Mark Anthony in Shakespeare\’s may have referred to \”the tears that live in the onion\”. But why do onions actually make us cry? And why do only some onions make us blub in this way when others, including related \’allium\’ plants such as garlic, barely ever draw a tear when chopped? When any vegetable is damaged, its cells are ripped open. The plant often then tries to defend itself by releasing bitter-tasting chemicals called that can be off-putting to hungry animals trying to eat it. But an onion\’s defence mechanism goes further, producing an even more irritating chemical, propanthial s-oxide, meant to stop the plant being consumed by pests.
This volatile chemical is what\’s known as a lachrymatory factor. Its volatility means that, once it\’s released, it quickly evaporates and finds its way into our eyes. There it dissolves in the water covering the surface of our eyes to form sulphenic acid. This irritates the lacrimal gland also known as the tear gland, hence the rather grand name of lachrymatory factor. Because the amount of acid produced is so small, its effect is only irritating and not harmful. The release of propanthial s-oxide was originally thought to be down to one enzyme in the onion known as allicinase, a biological catalyst that speeds up the production of the eye-irritating compound. But has suggested two enzymes could be needed to produces these eye-watering effects. This more complex explanation starts with the sulphur the onion absorbs from the ground and holds in a compound called PRENCSO 1 (1-propenyl-L-cysteine sulphoxide). When the onion is damaged it releases the allicinase, which reacts with the PRENCSO to produce ammonia and another chemical called 1-propenylsulphenic acid. The second enzyme, known as a lachrymatory-factor synthase, then turns this into the troublesome propanthial s-oxide. So why do some onions have more of an eye-stinging effect than others? There is lots of. One plausible explanation is that it\’s related to the amount of sulphur the onion has absorbed from the ground, which can depend on the soil and the growing conditions. Higher levels of sulphur in the soil help boost both the. Certainly sweeter onions tend to have less of the sulphur-containing compounds that eventually produce the propanthial s-oxide. But it\’s also possible that no two onions from the same bag will have the same effect, so cutting into the vegetable may be the only way to know if it will make you cry. However, we have a better idea why onion\’s cousin garlic doesn\’t have the same effect.
It contains a slightly different compound called, which doesn\’t breakdown further into eye-stinging chemicals. Instead it produces allicin, which has been linked to many of. Stop the tears One solution to the crying problem may be the humble onion by selective breeding or genetic modification to suppress the lachrymatory-factor synthase enzyme. This might also have the added benefit of improving how onions taste as less propanthial S-oxide would mean more thiosulphinate, the compound associated with the flavour of. There are also a number of lower-tech solutions that have been suggested to solve the. As the reaction involves enzymes, the rate of reaction and amount of irritating chemicals produced can be cut by either damaging the enzymes or slowing them down. In theory, (scalding them with boiling water then plunging them into freezing cold water) will denature the enzymes involved and so prevent the reaction from happening. This method is used when freezing many vegetables but it may not be practical to boil your onions before chopping them. Slowing the reaction can be achieved by by putting your onions in the fridge or freezer before chopping. But it\’s best not to store onions in a fridge in the long term as they become soggy and soft and lose their flavour, as well as making an. It is best to keep your onions in a cool dark place with air flow that is not as humid as the fridge. involve drawing the volatile chemicals away from you as you are chopping the onion. This could be done by using a cooker hood or running water, stopping the compounds making their way to your eyes. You can even buy goggles to stop the irritant reaching your eyes. But the ability of evaporated propanthial s-oxide to reach our eyes regardless means that even then you should be prepared to weep as you slice. , Senior Lecturer,. This article was originally published on. Read the.