Crying Over Onions

Ugh, I love onions... but HATE cooking with them. They make me cry!! Today my eyes even teared up with green onions. But, I wondered why and found the following information on TLC Cooking's Website under "Why do onions make you cry?"

Unless you're a chef with a freshly broken hear, the tears you shed when chopping onions aren't emotional ones. That leaves two other categories of tears: basal and reflexive. Since basal tears are the ones that hang around our eyes and eyelids to act as a lubricant, that leaves us with reflex tears. The lachrymal glands above the eyelids regulate the release of tears. In the case of reflex crying, an external irritant, such as dust or smoke, triggers nerve endings in the cornea to communicate with the brain stem. The brain registers the irritation in the eye then alerts the lachrymal gland to stimulate tear production to flush away the invader.

If we're chopping onions a few feet away from our eyes, what's causing this weepy reaction? The answer begins in the soil. Onions are part of the plant genus Allium, along with garlic, chives, leeks and about 400 other cousins. These vegetables absorb sulfur in the earth, which helps form a class of volatile organic molecules called amino acid sulfoxides. These sulfoxides are the real tear-jerkers when onions go under the knife.

As we chop up an onion, it releases lachrymatory-factor synthase enzymes. These catalysts instigate the chemical chain reaction that ends with you crying over the kitchen counter. These enzymes react with the sulfoxides and convert them into sulfenic acids [source: Scott]. Sulfenic acids are highly unstable and rearrange into a compound called syn-propanethial-S-oxide [source: Library of Congress].

When syn-propanethial-S-oxide (a pesky combination of sulfuric acid, sulfur dioxide and hydrogen sulfide) enters the air around our faces and approaches our eyes, it elicits the reflexive tear response described on the previous page [source: Norton]. Multiple nerve endings in the cornea register the sensation of the syn-propanethial-S-oxide as a substance that could harm our eyes. Consequently, the brain stem phones the lachrymal glands, and we commence to sniveling.

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When recipes call for yellow Spanish onions or other sharp relatives, you can try out a few tricks to ward off crying in the presence of onions:

• Chop an onion beneath running water.
• Turn on a fan while cutting an onion to scatter the sulfur compounds.
• Chill or cook an onion before chopping it.
• Use an onion chopping container.
• Wear goggles or glasses to protect your eyes.

But dry your eyes: Despite all of these tears, there is some good news. Supposedly, the more you cook with onions and endure their sting, the less they'll affect you over time [source: Hillman]. Just keep some lemons nearby to scrub the vegetable's strong signature scent off your hands.