Onions can make you cry because they contain a chemical compound called syn-propanethial-S-oxide. When you cut, chop, or crush an onion, it releases this compound into the air as this chemical is highly volatile. When the syn-propanethial-S-oxide comes into contact with your eyes, it reacts with the moisture present, forming a mild sulfuric acid. This acid irritates the nerve endings in your eyes, leading to the familiar burning or stinging sensation. In response to this irritation, your eyes produce tears as a protective mechanism to flush out the irritant and soothe the eye. The tears help to dilute and wash away the sulfuric acid, reducing the discomfort caused by the onion's compounds.
- 1. Cutting near running water: Cutting onions under a running tap or in a sink filled with water can help to wash away the compounds and reduce their concentration in the air.
- 2. Chilling the onion: Putting the onion in the refrigerator for some time before cutting can slow down the release of the volatile compounds, reducing their impact.
- 3. Using sharp knives: A sharp knife causes less damage to the onion's cells, leading to fewer compounds being released.
- 4. Cutting near a fan or open window: Increasing air circulation can help to disperse the onion's compounds, reducing their concentration around your eyes.
To minimize the effect of onion-induced tears, you can try a few strategies:
These methods can help alleviate the tears caused by cutting onions, but they may not completely eliminate the effect.