Why do onions make you cry, and what can you do about it? My brother told me about the simple trick he uses to process large batches of eye-burning onions without shedding a tear. In case you don't have the “trick” item on hand, I have other options that work pretty well to help you avoid “onion eyes”.
Why do Onions Make You Cry?
Short answer: Onions make you cry because they release a sulfenic acid in gaseous form. Yup – acidic gas. Tears are our bodies natural protection.
Science Focus give more details:
Onions take up sulphur from the soil while growing. This is combined with amino acids within the onion’s cells to form amino acid sulfoxides. In 2002, Japanese researchers identified an enzyme, also present in onions that unlocks the sulfoxides when the onion is cut. The resulting reaction produces sulfenic acid that rapidly reforms into a gas called syn-Propanethial-S-oxide. When this stuff hits the sensitive surface of our eyes, it causes the stinging that leads to tears.
Intrigueology has a pretty cool video on all the gory details. 🙂
What are the Health Benefits of Onions?
The World's Healthiest Foods details the health benefits of onions, including:
- protecting the heart
- supporting bone and connective tissue
- acting as an anti-inflammatory
- protecting from cancer
You get the most benefits when the onions are raw, but gentle cooking preserves some of them, too. Just don't turn your onions into charcoal.
Don't Cry Over Cut Onions – 4 Tips to Avoid Onion Eyes
#1 – My all time favorite technique (which was suggested by my brother) that I now use regularly for processing large batches of onions (for instance, when I'm canning salsa), is to put a small fan on the counter next to where I'm chopping. Use the fan to blow away the sulfenic acid gas and keep it out of your eyes – no tears.
I've got a little Massey personal fan that we received as a hand me down from my in-laws. A larger fan would work, too – the small ones are just more convenient (and pretty inexpensive).
Now, if you don't have a fan handy, there are some other options you can use to avoid crying while slicing or chopping onions:
#2 – Chill your onions in the fridge or freezer or by running them under cold water
Chilling reduces the oxidation rate, meaning they produce less of those irritating compounds. Also, hot air and hot gas (including sulfenic acid laden gas) rises faster than cold gas, and cold tends to be less irritating than hot. The water will dilute the juices so less of them get airborne.
#3 – Wear goggles to block the onion fumes
This will keep fumes out of your eyes, but unless you've got sealed goggles, you're still still going to get it. Plain safety glasses won't cut it. I don't like the really flimsy ones, either. A couple extra bucks will get you ones that are fog and impact resistant for other tasks.
#4 – Cut Your Onions with a Very Sharp Knife
One of our readers (Kevin) shared a tip from culinary school:
During my attendance at Culinary School many years ago, the simple trick taught to prevent the onion cry, is to use a very sharp knife. I can chop dozens of room temp or chilled onions in my tiny apartment kitchen and not shed a tear, if I use a sharp chef’s or paring knife…
Another reader, Sherry, agrees:
A few years ago I got a SUPER good chef’s knife. (Shun) It greatly reduced the amount of tears when I chop onions because it’s so sharp it doesn’t break as many of the cells. Not to mention how much less effort it takes to cut stuff up!
#5 – Chew gum to breath fewer onion fumes
If for some reason you are really desperate, don't have a fan, or refrigeration, or water or goggles, yes, chewing gum does help – a little. It works because you tend to breathe through your mouth more, so you suck less gas into your nose/sinuses. Feeble relief at best, but it might distract you enough to make you less miserable.
If you've enjoyed this post, Like it, Pin it, Stumble it, Share it. Help end needless onion pain. 😉
You may also enjoy:
- 35+ Handy Kitchen Substitutions – Printable List
- How to Harvest, Cure and Store Onions – Root Cellaring, Braiding, Dehydrating and Freezing
- How to Get Rid of Ants Naturally
Originally posted in 2015, updated in 2017.