Are Leftover Onions Really Toxic? Why Do Onions Make Me Cry?


(Scroll down for the answer to the question:  Are leftover onions poison?)

I love my onions, be it yellow, white, sweet, pearly, green or red!  Of course, I cannot leave out their close cousins:  shallots, scallions, leek, garlic, chives, and many more species belonging to the “genus Allium” family (up to 800), and that’s without including the wild specimens.  Oh!  How I would love to explore each one of these!

Factoid:  Did you know the onion is the most widely cultivated species of the genus Allium vegetable?

If you’re like me, you use these vegetables daily.  In fact, I believe I use either onions, garlic, leeks or chives in every one of my dishes including some of my breakfasts.

Although I love this versatile and tasty vegetable, I find it to be a tear-jerking task to chop, slice or mince the onion.  I’m sure you know what I mean.

William Shakespeare wrote:  “The tears live in an onion that should water this sorrow.”

So, I wondered, what is it with the onion that makes us cry?

*You will notice I sometimes add links to my posts.  I add these because I am convinced that they’re awesome products and I feel they merit a thumbs up and should be shared with others!  If you decide that you agree that these are worth your while to purchase by clicking on these links, then I could receive a small compensation which enables me to keep posting on my blog.  Thank You for your support! 

With a bit of research, I discovered that it’s all about the chemistry.  The instant we plunge a knife through its skin,  we’re in fact bursting cells which release some of their compounds.  In a flash, the onion’s defense mechanism triggers a chemical reaction and forms a sulfur-based gas called Propanethial s-oxide.  At this stage,  our eyes kick into protection mode by tearing up.

Interestingly, tears produced by emotions are different then onion tears under a microscope.  

There are three major groups of tears:

  • basal (the ones responsible for lubricating the cornea);
  • reflex (protects our eyes from irritants, such as smoke, wind or onions for example);
  • psychic (triggered by intense emotion, happy or sad).

*Here is a link to a fascinating study on the composition of tears and how each tear is as unique as a fingerprint.  

Since 2008, a false rumor about the onion spread across the internet like wild-fire.  You know the one where leftover, raw onion stored in the refrigerator is poison?? Although many found this statement to be foolish, some are less shrewd and believe this to be a fact.  According to the National Onion Association website, it seems that this post has been deleted from the internet in 2009.  You can find a pdf letter link on the National Onion Association website in the sectionMyths about the onion.”  Part of this letter states the following:

“There is not any scientific basis that cut onions are a magnet for bacteria. According to
the Center for Food Safety at the University of Georgia, juice released from cut onion is
known to kill or inhibit the growth of several types of microorganisms, including some
capable of causing human illnesses.

When cut, onions release compounds that do not promote pathogen growth. This is the
same compound that causes our eyes to produce tears. When handled properly, cut
onions can be stored in the refrigerator in a sealed container for up to 7 days.
The claim about onions in the article by McCann has caused a great deal of concern.
Please pass the word along to your family and friends that onions can be enjoyed when
handled properly.”

Tips on how to chop an onion without the tears (some are practical while others are quite funny):

  1. Stick the onion in the freezer 10-15 minutes prior to chopping (lowering their temperature will reduce the toxins);
  2. Plunge a peeled and halved onion in water for a bit (downfall is that the onion loses some of its flavors with this method);
  3. After peeling the onion, halve it and place the cut portion down on your cutting board and then either dice or slice;
  4. Always use a very sharp knife when chopping or slicing an onion (the enzymes are released from the onion when it’s crushed or broken- which would be the results of using a dull knife);
  5. Chew gum (this forces you to breathe through your mouth and apparently it works);
  6. Cut the onion under water in a bowl (that would be difficult, in my opinion);
  7. Chop an onion near a kettle of boiling water (the steam will dissipate the irritants from the onion);
  8. Breathe through your mouth and stick out your tongue (lol! You might want to try this one in private and away from a window);
  9. A fan pointed in such a direction as to send the toxic mist away from your eyes;
  10. Stick a piece of bread in your mouth and chew very slowly while having a portion of the bread hanging out of your mouth (very interesting);
  11. My favorite:  wear swimmer’s goggles or chemistry goggles that fit properly.
  12. Use a mini processor or chopper.

*Beware:  Onions are dangerous for your dog or cat (they damage the red blood cells).

Although some of the above methods prove to be useful, I just prefer to use my KitchenAid mini food processor.  It’s quick and simple with absolutely no tears!

I found mine here on for $49.99 (I don’t know if this is a limited time promotion, but I didn’t wait, I grabbed it.  After comparing prices with Canadian Tire- $85.99, and Walmart- $79.99, this proved to be a great deal!)!  Even better, if you’re in the USA, it’s currently on sale for $29.99 here.  Why are things so much cheaper in the US?

I chose the apple green color to match the theme of my blog, but there are 10 beautiful colors to chose from).


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