What kitchen technique can speed up chopping onions without tearing your eyes (e.g., chill them first)?

Question

Chill onions before chopping or use a sharp knife to reduce eye irritation from released sulfur compounds.

Answer 1

Chilling onions for about 30 minutes before chopping can significantly reduce tearing. This slows down the release of the irritating compounds.

Detailed Explanation:

Chopping onions releases propanethial S-oxide, a volatile sulfur compound that irritates the eyes, causing them to tear up. Chilling the onion before cutting slows down the enzymatic reaction that produces this compound. The cold temperature reduces the volatility of the gas, meaning less of it reaches your eyes. To chill an onion effectively, place it in the refrigerator for at least 30 minutes before you plan to chop it. You can also briefly put it in the freezer for about 10-15 minutes, but be careful not to freeze it solid, as this can affect its texture. When chopping, use a sharp knife to make clean cuts, as crushing the onion releases more of the irritating compound. Some people also find that chopping onions under a running range hood or near a fan helps to direct the gas away from their face.

Pro Tip:

Cut the root end of the onion last. The root end contains the highest concentration of the irritating compounds, so leaving it intact until the very end minimizes exposure.