Onion Tears

By Tanya Piacentini

Published on January 2, 2009

I've never met an onion that didn't make me weep. The knife goes in, what begins as a tingling soon builds to a burn, and then, cue the waterworks. Recently I became determined to learn what lends onions their incendiary power—and how I might subdue it.

Thumbing through scientific articles, I ascertained that, until we apply the knife, an enzyme and a sulfur compound coexist peacefully in onions. Once the onion's cells are pierced, the two combine to form a volatile chemical that, when airborne, irritates the tear ducts. My research into possible antidotes yielded less conclusive results. My covering my eyes with goggles warded off a few tears, but I still felt the burn (and a little foolish besides). I went on to unearth old wives' tales about biting down on a matchstick, as well as conflicting advice regarding whether an onion should be frozen or soaked in cold water before chopping. None of my findings led to dry eyes.

Then I reached Barry G. Swanson, a food scientist at Washington State University, who seemed to talk sense. Goggles are fine, he said, but "injuring as few of the onion's cells as possible" is really the way to go. He recommended using a freshly sharpened knife, capable of penetrating the bulb quickly and cleanly. And while a stopover in the freezer or in ice water might slow the progress of tear-inducing compounds, "freezing will result in a less crisp onion, and soaking removes flavor". Better to rely on an open window, running water, or a flame to draw away and purge some of the onion's irksome fumes. "I burn a few candles," he said. I have since taken to doing the same, completing my fail-safe mise-en-place: a sharp knife and an enchanting ambience.

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