How to Prevent Onion Tears?

Mother asked me to prepare meat and vegetables for cooking.  I washed meat and sliced it in cubes. Wash vegetables and chop it. Peeled few pieces of garlic and chopped it very finely.

The last part was really hard for me. It was the peeling and slicing of onions.  My eyes got irritated and tears began falling. The feeling was really uncomfortable. I need to wipe my teary red eyes very open. I used to wear sunglasses to protect my eyes from onions fumes.  I thought that was a good idea like wearing a helmet when you’re driving a motorcycle.  But my tears keep on falling even if I have shades to protect my precious eyes. Hmmm!

Onions produce the chemical irritant known as syn-propanethial-S-oxide. It stimulates the eyes’ lachrymal glands so they release tears. The process goes as follows:

  1. Lachrymatory-factor synthase is released into the air when we cut an onion.
  2. The synthase enzyme converts the sulfoxides (amino acids) of the onion into sulfenic acid.
  3. The unstable sulfenic acid rearranges itself into syn-ropanethial-S-oxide.
  4. Syn-propanethial-S-oxide gets into the air and comes in contact with our eyes. The lachrymal glands become irritated and produces the tears!

There are ways to prevent crying when dealing with onions.

  1. cut the root off last;
  2. refrigerate before cutting;
  3. peel them under cold water;
  4. have a fan behind you or alongside to blow the vapors away;
  5. place a piece of bread on the knife tip to absorb the fumes;
  6. chew gum while peeling and slicing onions.
  7. hold you breath and cut them as quick as you can
  8. have someone else cut them for you! But be ready to get some words of anger !


Marvin is the lead chocolate maker of Ben and Lyn Chocolate Inc. Has strong background in food research and development. Occasionally conducts training and lectures. Lecturer of Cocoa Foundation of the Philippines. Do coaching and consultancy services on his free time.

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