It’s all about chemistry! đŸ˜ We’re breaking down the science.
When you chop an onion, you break open its cells and release enzymes and sulfur-containing compounds that quickly react to form a gas called syn-propanethial-S-oxide. This gas floats up into the air and reaches your eyes. Upon contact with the moisture in your eyes, it transforms into a mild sulfuric acid that irritates the tear glands.
Your eyes respond by producing tears to flush out this irritant—this is the reason you end up crying while cutting onions. This natural defense mechanism evolved to protect onions from animals.
Interestingly, different onion varieties produce varying amounts of these chemicals, so some onions cause more tears than others. Scientists have even developed tear-free onion varieties by turning off the gene that produces the tear-inducing enzyme, although these tend to have milder flavors.
For now, a simple way to reduce tears while chopping is to use a sharp knife and cut slowly or chill onions before cutting.
Tag someone who always cries when chopping onions!
