Why do our eyes water when we cut onions?

Most of the Indian cooking requires onions to enhance the taste of their Biryanis, curries, and salads. The first job of the chef will start with cutting onions. It is a common experience that as soon as we start chopping onions we start tearing up. Rubbing the eyes will further make it worse.

Let us decode why our eyes water when we cut onions, as we cannot stop eating onions which are rich in Vitamin C and lowers cholesterol apart from adding great taste to our dishes.

  • While chopping onions, cells inside the onions break and releases Lachrymatory-factor synthase, which forms the sulfenic acid.

  • The acid when mixed with enzymes, forms a gas called propanethiol S-oxide.

  • This gas when reaches our eyes gets mixed with water in the eyes and forms sulphuric acid.

  • This sulfuric acid makes our eyes sting, which results in tears, and the more water produced in our eyes leads to the production of more acid and thus more irritation.

  • When you start cooking onions, it deactivates the enzymes and stops releasing the gas.

There are many ways to escape this tearful experience.

  • Using a sharp knife to cut the onion will reduce the amount of damage to the onion cells, and thus leads to less release of gas.

  • Keep the onions in water after taking off the peel. Onions cut into halves and quarters will be more helpful. Keeping the onions in the freezer for 10-15 minutes will also help.

  • Many say taking out your tongue while cutting onions will stop your eyes from tearing because this way the gas will be absorbed by our tongue.

  • Wearing swimming goggles

  • Chewing gum during cutting onions might help.

  • Professionals don't face this problem often as they chop fast and do less damage to onions cells and also this does not give time to the gas to reach the eyes.

Updated on: 27-Jun-2020


Kickstart Your Career

Get certified by completing the course

Get Started