Onions vs Tears

By : Godoctr Team    Posted : 28-03-2016    3025    4    Like
Onions vs Tears

"Life is an onion- you peel it year by year and sometimes cry."
-Carl Sandburg
But have you ever wondered why you'd cry if you had to be chopping an onion? Well, it has everything to do with the water in your eyes. Applying basic chemistry, you know, when a gas reacts with water, acid forms. So yes, that's acid in your eyes causing the tears and the stinging, yikes!
What actually happens: When you cut an onion, the cells of the onion are broken open, and the enzyme Lachrymatory-Factor Synthase is released into the air. This enzyme then reacts with the amino acid sulfoxides in the onion to convert them into sulfenic acid. Being unstable, the acid rearranges itself into Syn-Propanethial-S-oxide. The gas comes in contact with the eyes by diffusion through the air, and stimulates sensory neurons. The compound is an irritant, and is diluted and flushed out by the tears released from the tear glands.
These tears are involuntary, but measures can be taken to reduce the effect:
  1. Putting them in the freezer: According to the TV Show 'Food Detectives', this is the most effective way to reduce the amount of enzyme released. Keep them in the freezer (or the fridge) about 20 minutes before you cut them. Note that this won't affect their taste at all.
  2. Using a really sharp knife for the cutting: It will slice through the onion instead of crushing its cells. Resultantly, fewer enzymes will be released.
  3. Sticking your tongue out and mouth-breathing: Let the gas react with the water on your tongue, and save yourself a bout of stinging tears. No tears will be generated, because the olfactory nerves, which are close to the tear duct nerves, will be bypassed.
  4. Cutting the onion under water, or near hot running water or steam: The steam will attract the vapor from the onion, and dissipate it. You could also cut it near a strong draught, like one from a fan- it will pull the gas away. When cutting it under water, the gas will obviously react with that much water which is also easily available nearest to the onion, sparing the water in your eyes.
  5. Wearing swimming goggles to directly protect your eyes
  6. Wearing contact lenses to create a barrier between the gas and your eyes
  7. Lighting a candle near where you cut the onion: The flame will attract the gas.
  8. Splashing the chopping board with vinegar to denature the enzyme
  9. Whistling to create an airflow away from your face
  10. Pointing the tubes of the onion away from your face

Remember to not compromise with your eyes when you cut an onion next!

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