Why Do Onions Make You Cry? Here’s How To Cut Without Tearing Up

Let’s decode the onion theory and understand that why do onions make you cry? And some tips that you can follow to save those precious tears.

Charu Sharma
Written by: Charu SharmaUpdated at: Jun 03, 2021 14:36 IST
Why Do Onions Make You Cry? Here’s How To Cut Without Tearing Up

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Even if you love to cook food and it is your hobby, there might undoubtedly be something that would make you think twice. One of them could be chopping onions. Used in various foods from curries to soups and from sauteed vegetables to lentils, onions find their way into everything. Every time you chop them, your eyes sting, tears run down your face, and you get a stuffy nose. Let’s decode the onion theory and understand that why do onions make you cry? And some tips that you can follow to save those precious tears.

What in onions makes you cry?

The science behind tearing up every time while chopping, deciding or slicing onions is pretty fascinating and consists of biochemistry. Onions are actually equipped with a self-defense mechanism which helps them to grow. As onions are grown underground, they need to protect themselves from rodents who might pick over the bulbs or roots early and become a hindrance to their growth.

When you cut an onion through you are actually performing a chemical reaction by releasing the liquidity content which makes the previously separated enzymes to come together which looks something like this-

sulfur-rich amino acids + sulfenic acids = syn-propanethial-S-oxide (gas)

Let me make it a little easier for you all. Onions have some great sulphur absorbing properties, when the skin of an onion is broken, they discharge sulfenic acid and the amino acids. These two combine together to produce an easily vapourible chemical syn-propanethial-S-oxide. As the chemical formed is easily vaporized, it floats in the air and comes in contact with your eyes. Being a lachrymatory agent (tear generating) when syn-propanethial-S-oxide comes in contact with the watery layer of human eyes it turns into sulphuric acid.

syn-propanethial-S-oxide + watery eye layer = Sulphuric acid

It is not just onions which come with a self-defense mechanism, but humans do too. In order to protect our eyes from any kind of damage that can be caused due to the sulphuric acid, they start tearing up so that the toxins can be flushed out with the tears.

Also Read: Do You know Onions Can Aid Weight Loss ? Here Are Some Ways To Consume It

Which onion makes you cry the most?

What if I tell you that was not all the onion tears theory but there is a little more to it. The intensity of the above process depends upon two other factors.

  • How sensitive the person it
  • What kind of onion you are cutting

To our surprise, it's not all the onions that will stuff your nose, make you cry and make your face go red all so harshly. Different types of onions have different amounts of sulphur present in them. The more sulphur present in the onion, the more harsh it will be. Yellow, red, and white onions are the harshest, containing lots of sulphur compounds, whereas the sweet onions like green onions are less pungent and contain less sulphur and hence produce fewer tears. 

Also read: What Are The Uses Of Onion Water? Here's How You Can Make It

How Not To Cry While Cutting Onions?

Here are some tips which will help you to have a tear-free onion chopping experience-

  • Rub some lemon juice on the knife which you are going to use. Repeat this method after a few cuts.
  • Freeze the onion for about 10-15 minutes before cutting them.
  • Sit near a fan so it will help to blow the fumes away from your eyes.
  • Make as sharp and clean cuts as you can with the help of a sharp-bladed knife.
  • Cut the onions under running water.
  • Light a candle nearby so that the candle flame will take away some of the tear causing fumes.
  • Stick a piece of bread in your mouth so that the onion fumes would get absorbed by the bread.
  • Keep the onion root until you are done chopping the whole onion
  • After removing the outer layer, keep the onion in icy-cold water for 5-10 minutes.

These were some prevention tips from our end, which you can follow the next time you go to chop those onions so that you can have a tear-free happy chopping experience.

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