Why Do You Cry When Cutting Onions?

A cutting board of various onion varieties

We’ve all been there…you have company, you’re busy in the kitchen finishing up and you need to chop some onions for the salad. All of a sudden the tears start flowing and your mascara is running down your face before you can grab a tissue. Why do you cry when cutting onions anyway and is there a way to stop it?

Maybe it’s just me but have you ever noticed that sometimes you cry more cutting onions than other times?  Is it the onion?  Is it how you are cutting it? 

For questions like this, I tend to go to a number of favorite sources to find the answer.  For this one the first place I turned to was my favorite Food and Cooking reference #onmykitchenshelf – Harold McGee’s “On Food and Cooking: The Science and Lore of the Kitchen”.  Yes, it’s a bit technical, but then, I’m kind of a foodie geek so it’s right up my alley.  While he goes into depth about the “why we cry”, I had to go to a few other sources for the “how to reduce crying”.

Why Do Onions Make You Cry?

So first, why do you cry when cutting onions?  Onions have a sulfur-containing chemical, or enzyme, called sulfoxide, in the cell walls of the onion.  That enzyme is what gives onions their characteristic bite, or pungent flavor.  According to Magee, the sulfur’s purpose is protective – to keep animals from eating the plant. Isn’t nature amazing?   

For us, that sulfur-containing enzyme is what provides that sharp oniony bite but is also what causes us to tear up.  When you cut into the onion and break open the cell, that chemical releases into the air, combines with other compounds, and is what hits the nerve endings in our nose or eyes and causes our eyes to sting and tear ducts to well up. 

Which Onions are the Most Tear Inducing?

Since it is an enzyme in the onion that causes our tearing up, you might be wondering why certain onions cause more of an issue than others…or do they? 

Well, yes, there are onions that have more of that sulfoxide enzyme than others and certain onions are bred to contain less.  Sweet onions, for example.  They are apparently grown in a lower sulfur-containing soil and bred to have less of that pungent flavor.  With less sulfoxide, you may find that you tear up less, or not at all.  Yellow onions are apparently bred to be very pungent, as are red onions, so, you may find yourself with tears dropping on the cutting board.  Leeks and scallions are less pungent as well.

Are there Tricks to Minimize Tears When Cutting Onions?

Sweet onions tend to be my “go-to” onion for a lot of things, but there are times when only a red onion or yellow onion will do!  So, are there tricks to help minimize the tears?  Are “onion goggles” a necessary kitchen utensil?  I don’t own goggles so I can’t say if they work or not but they make sense.  However there are a few tricks I’d try before investing in another kitchen gadget! 

  • First, use fresh onions.  Onions that have been stored for a while have softer cell walls and when you cut into them more of that sulfur chemical releases, causing more tears!
  • Second, you could try freezing the onion for a few minutes before you cut it.  The cold ties up the chemical causing it to release from the cell at a much slower pace.  The same is true if you submerge the onion in ice-cold water for a few minutes before cutting it. Just make sure you dry the onion well before cutting it so your knife doesn’t slip!
  • Third, and okay, this one sounds crazy, but supposedly it works.  Put a small piece of bread either in your mouth and hold it in your teeth or on the end of the knife and then cut the onion.  The bread soaks up that sulfur compound!  I know, you may look crazy but, if it works, well, it might be worth a few minutes of crazy to prevent runny mascara!

So there you have it!  It’s a matter of the type of onion and how you cut it that will determine how many tears you shed!  Give it a try and let me know if you have any tricks that have worked for you. And definitely let me know if you try the bread trick!

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