There’s a reason so many recipes start with chopping onions. Onions are a great way to build flavor in a dish. However, there’s a downside to all of that delicious, flavor-generating sulfur. It seems virtually impossible to chop an onion without crying, and any cook knows that chopping onions releases chemicals that sting.
What is this? Tear gas?
Onions get their distinctive flavor from sulfur, which they absorb from the soil they are grown in. The plants deploy this chemical when their tissues are broken by biting or cutting. The chemicals are highly irritating, and discourage most creatures from coming back for seconds. They kill microbes and repel insects, and they damage the red blood cells of dogs and cats. Never feed your pet onions or garlic in any form.
According to The Daily Meal, “We can blame it all on an enzyme called synthase. Synthase converts the sulfur molecules that are released when an onion is cut into sulfenic acid. The sulfenic acid, in turn, rearranges itself into a chemical that floats in the air, comes into contact with our eyes, and causes irritation – enough irritation to make us cry.”
When we eat raw, sulfur-rich onions, they are sharp and pungent, but when they’re cooked or caramelized, the various sulfur compounds react with one another and new flavors develop from sweet to nutty.
Armed with sharp knives and wooden cutting boards, two of The Daily Meal’s recipe editors did a 2-days of experiments to test if some of the common claims were fact or myth.
The editors did agree with claims that “one can build up a tolerance to the lachrymatory effects of cutting onions” by doing it often, and I would agree. After years of cutting onions, I don’t even notice a sting, but I sure did as a new bride.
So how do you keep from shedding tears when you you first start out cooking with this essential ingredient?
1. Cutting an onion under water was effective.
2. Breathing through your mouth, not your nose, help many.
3. Freezing onions for 10-15 minutes make them milder before cutting.
4. Refrigerating onions for 30-40 minutes lessened the sulfurous chemical reaction.
5. Chopping off the root end and leaving it intact produced fewer tears (which is consistent with claims that the root end of the onion has a higher concentration of sulfuric compounds than its other parts).
6. Wearing goggles while chopping onions worked (in another trial) while wearing glasses did not work for these testers.
7. Pampered Chef teaches its sales personnel to cut off 1/2″ of the base where the roots are so it sits flat. They then quickly score an ‘x’ into the flesh of the base and leave on the counter for a bit so it can drain out some of the juice that holds the acidic gases. I do this one.
8. They stated that you should put a match in your mouth, but they did not say whether it was lit or not! I would not try this one at home.
9. They found first microwaving an onion is supposed to work, but no word on how long.
10. Rubbing lemon juice on the blade of the knife worked. Maybe a chemical reaction lessened the sulfur’s effects?
11. Running a fan to blow the gases away from the testers worked.
12. Using a very sharp knife did help.
Maybe these tips will reduce or eliminate the need to cry next time you’re chopping onions. I can’t imagine too many meals without this healthful and flavorful bulb somewhere in the recipe.
Thanks for reading!