Wednesday, October 8, 2008
Chemical warfare in the kitchen
Maybe you already know why chopping onions brings tears to our eyes, but I certainly didn't, and neither did The Washington Post's Andreas Viestad, until he wrote (and I read) this article. Here's a summary:
The lachrymatory, or tear inducing, chemical responsible is characterized as propanethial S-oxide, which is a light and volatile chemical that is also water-soluble. So yes, you could assume that chopping the onion under water solves the problem but not only is that dangerous, it dulls the flavor.
Cool the onion in ice water before chopping. It slows down the speed of the lachrymator (tear inducer) and reduces its volatility.
Use a sharp knife. Onions are made up of cells. Think middle school chemistry class. The lachrymatory chemical is released only when those cells are ruptured are the compounds released into the air in a significant quantity. A dull knife will bruise and fracture a more cells than a sharp, precise one.
Use Andreas Viestad's technique: "I go for a moderated application of the principle: chopping onions next to running water, on a wet cutting board. With so much water around, much less of the offensive substance reaches my eyes."