Why do onions make you cry

Chopped Onions

If you have ever chopped an onion in your life, you must have experienced the awful situation of tears running down your cheeks during the slicing process.  Forget doing it for real, the mere thought of chopping onions makes me cry. So, what’s the reason behind the same? Why do onions make you cry? The answer lies in the fact that onions, when cut, produce a chemical irritant known as syn-propanethial-S-oxide that stimulates the lachrymal glands in our eyes and cause them to tear. Let’s discuss in detail how it happens.

Onions contain amino acid sulfoxides that create sulfenic acids inside the onion cells. The sulfenic acids and the enzymes stay separate in the cells, but when you start cutting an onion, these chemicals start mixing with each other and with air to release propanethial S-oxide, a volatile sulphur compound. The gas produced starts moving towards your eyes and reacts with the water in your eyes to form sulfuric acid, which starts irritating the nerve endings in the eyes. At the same time, tear glands get to work and start producing tears to dilute and wash the irritant.

How to chop onions without crying

1. Keep onions in the freezer for about 15 minutes before you start slicing them. This process minimizes the production of propanethiol S-oxide.

2. Use a sharp knife to slice the onions. Using dull knifes crushes the onion cells to release more enzymes.

3. You can light a candle while cutting onions. The gas releases while chopping onions move towards the candle flame instead of your eyes.

4. You can also avoid slicing the onion till the root, as this part carries the maximum concentration of sulfides.

5. Do not forget to soak the onion in water before slicing.

6. Breathing through mouth instead of nose while cutting onions can save you from tears.

7. Use onion goggles, any other airtight goggles or contact lenses.