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  • Category: Cooking Queries

    Why do we get tears when we chop onions?

    Why do we get tears while chopping onions? I chop everything but not to onions its so irritate. Do you have any idea how to stop it ?
  • #141647
    Chopping the onions are not that easy and many households ran away from this task and give the same to the elders to do the needful. Getting tears is the natural phenomenon as we chop the onions, the wet content inside the vegetable brings instant tears and is some times irritating too. Being grown from inside the ground, the moisture present inside onions bring those tears instantly. But we can avoid the same by pealing of the out cover in full without cutting the onion into two halves. When every onion is peeled off that way then cut the same into two and keep the cut portion ground side and chop it with tiny pieces. You wont get tears that much.
    K Mohan
    'Idhuvum Kadandhu Pogum "
    Even this challenging situation would ease

  • #141648
    I think this should be shifted to 'Ask Expert' section. The reason is scientific in nature.
    Caution: Explosive. Handle with care.

  • #141649
    This thread is being shifted to Ask Expert section.
    'Real knowledge is to know the extent of one's ignorance'- Confucius

  • #141658
    Irritation in eyes while cutting or chopping onions is a common sight in our households.
    There is a chemistry behind this phenomenon and following is the scientific reasoning which explains this.
    When onion is cut, the exposed parts get in contact of air and in this process sulfenic acid is formed. Sulfenic acid is a unstable acid and soon it rearranges itself in a compound known as Syn-propanethial-S-oxide.
    The vapours of the compound Syn-propanethial-S-oxide gets into the air and comes in contact with eyes and irritates the eye.
    So next time you chop onions change your place along with onions a few times to avoid the air already filled with the vapours of this irritating compound.

    Knowledge is power.

  • #141665
    The irritation is basically due to a gas released during the slicing of the onions. The name of the gas is Propanethiol S-oxide. This gas continues emitting until the entire onion is chopped or shredded or grated.
    I would like to add one fact that coming of tears when you chop onions is a bit overrated. This is shown a lot in Bollywood movies to emphasize on a comic scene. Since I work in the kitchen, I know what the truth is. The truth is while chopping onions only mild irritation of eyes are predominant. Tears don't come as much. Profuse tears come when we shred or grate onions. Now you know the reason why.
    Now to answer the last part of your question, it is usually said that, if you chop onions with a very sharp knife tears don't come. But what happens if you shred or grate onions? It's better to always wash your hands thoroughly after grating or chopping onions. Then wash your eyes with cold water.

    Live life Kingsize!

  • #141667
    When onion is chopped, it produces a chemical named syn-propanethial-S-oxide. It is a chemical which causes irritation to the nerves of our eyes, causing activation of tear glands.

    Irritation of eyes while chopping onions can be partially prevented if a sharp knife is used or the onion is soaked in water before chopping.

    Caution: Explosive. Handle with care.

  • #141738
    When we chop the onion, each cut releases the Lachrymatory-factor synthase into the air. And into the air synthase enzyme convert the amino acid into sulfenic acid. This in turn converts into syn-ropanethial-S-oxide. And when this part comes into contact with our eyes, this leads to irritation inside the eyes. And eventually this leads to tears. This process happens so quickly that it becomes harder to notice. Often this is avoided by keeping the onion into the water before cutting it. This way the process of conversion into syn-ropanethial-S-oxide is avoided. Some people also use the food processors to make it quick to slice and avoid the tears.

  • #141762
    We get tears while chopping onions due to sulphur gas release from it. It always irritate us. To avoid irritation we can wear a goggles it will reduce tears. Never try to rub your eyes it is not a good habit. One more thing you can do to reduce tears. Wet onions into water before chopping. Wet onions will reduce irritation.
    Honesty is the best policy.

  • #141798
    Here are few things you can do Here are few things you can do to avoid crying while cutting onion
    Before or while cutting Onion try these
    1. Deep Freeze onion for 15 mins.
    2. Cut Onion under cold running water
    3. Chew the Chewing gum
    4. Turn on the fan just between your face and above chop board. This should throw away Sulphur reaching to eyes.
    5. Refrigerate Onion 30 mins before cutting.
    6. Keep Match from Matchbook in front teeth or keep bread in mouth with more part outside. Both of them absorbs Sulphur.
    7. Not remove roots of Onion while cutting. Cut it at the end of chopping.
    8. Microwave Onion as it is 30 seconds before cutting.
    9. Use very sharp knife so that Onion don't get squeeze to release Sulphur
    10. Cut onion as it is with it's cover on and remove it later.

    Avi
    Life Is Beautiful

  • #142099
    When you cut an onion, they produces a simultaneous chemicals which unleashes PS-Oxide by which the irritant causes our eyes to fill with tears. Inorder to prevent tears, one has to chop the onion in such a way that will produce less irritant and to prevent one's eyes from reaching through. One best way is to give less damage to the onion cell wall using a good and sharp knife.
    Be the Hero of the zero hour!

  • #143244
    When you cut an onion that damage cells of the onion and that cells release their content. The enzyme present in the onion namely alliinases that breaks down aminoacid sulfoxides and that generate sulfenic acids. There are several sulfenic acids among these 1 - propenesulfenic acid mix with second enzyme that is called lacrimatory factor synthase and produce the gas propainthiol s -oxide. These gas induce tear in eyes.

  • #143245
    TThis response is marked as DELETED by the admin.

    hi friend
    When you cut an onion that damage cells of the onion and that cells release their content. The enzyme present in the onion namely alliinases that breaks down aminoacid sulfoxides and that generate sulfenic acids.
    There are several sulfenic acids among these 1 - propenesulfenic acid mix with second enzyme that is called lacrimatory factor synthase and produce the gas propainthiol s -oxide.
    These gas induce tear in eyes.

  • #143246
    Some chemicals inside the onion (mentioned in earlier answers) rise up as vapour and hit our eyes. The chemicals being foreign body, our eyes flush it out by producing copious tears. If the vapours can be arrested from rising up and reaching our eyes, then tears won't come.
    So keeping the onions inside water while cutting can prevent tears. The same can be obtained if we carefully place a small fan or blower to blow the vapours away from us. If we suck the air by opening our mouth while cutting onions then also the tears can be prevented. Of these, the first said one is most effective .


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