Onion is a diabolical vegetable. Why, you might ask? Well, apart from being responsible for giving you bad breath, it also makes you cry. Onions might be a great way to give your food a strong and tangy flavour, but the process of getting the chopped veggie onto your plate is eye watering, quite literally. While you may enjoy a delicious meal of biryani flavoured with masalas and onions, your chef knows the real struggle of putting the meal together. So why does chopping an onion make your eyes burn and all teary? Let us find out.
The simple answer
Understanding exactly what causes onions to produce tears is not easy, what with all the science involved. But in a nutshell, it is because of the chemicals present in an onion. Onions contain amino acids called sulfoxides, and when they are cut into, their cell walls get damaged, causing the sulfoxides to convert into a dreadful gas. It is this gas that comes in contact with your eyes and causes a burning sensation. Your tear ducts react by producing tears as a defence mechanism to get rid of the gas from the eyes. Hence, the crying.
The science based answer
Ignore this version if you are intimidated by science. But for those of you who are curious, this is what goes on, according to the world of science. When you cut an onion, lachrymatory-factor synthase is released into the air. The synthase enzyme converts the amino acid sulfoxides present in the onion into an unstable sulfenic acid, which rearranges itself into syn-Propanethial-S-oxide. It is the syn-Propanethial-S-oxide that is released into the air which comes in contact with our eyes. It irritates the lacrimal glands, which then produces tears.
Why only some people are affected
Have you ever wondered why some are more severely affected by the chopping of onions than others? While you are struggling to keep your eyes open, there will always be that one person who remains unperturbed by the effect of chopped onions. There is a simple explanation for that. Some people just have more sensitive lacrimal glands than others, causing them to get triggered more easily. Unfortunately, this physiology cannot be altered.
How to prevent burning and tears
Here are a few ways to prevent onions from giving you a hard time.
- Freeze the onion around fifteen minutes before chopping it, or better yet, store your onions in the fridge. Lower temperatures slow the conversion of sulfoxides into that eye tingling gas.
- Another way to reduce the temperature of the onion is by soaking it in cold water. This is however more time consuming and less efficient than freezing it.
- Chop you onions facing a fan. The air from the fan helps in blowing the gas away from your face.
- A sharper knife provides more cutting precision, damaging the cell walls lesser, and therefore releasing less gas.
- Last but not the least, if your eyes are too reactive to the painful gas, try wearing goggles. It may sound, or even look silly, but at least you won’t have to go through the pain.