Masterpiece Theatre presents: Tears of an Onion.
This is Sandra Tsing Loh with the Loh Down on Science.
Cut an onion, and enzymes break up sulfur compounds. But how do they get in your eye?
Zixuan Wu and team at Cornell University compared onion cutting with varying knife sharpness and speeds. With high speed cameras, they caught droplets released from cut onions.
The tear-triggering compounds eject in two stages. First, a high speed mist of droplets and then a slow splash. The fix? Cut the onion slower with sharper knives!
And the bigger picture? Careful onion cutting could also reduce the spread of pathogens, along with tears!
And that’s worth filming! In 4-K! For the Criteri-onion Collection!
Reference: Wu, Z., Alireza Hooshanginejad, Wang, W., Hui, C.-Y., & Jung, S. (2025). Droplet outbursts from onion cutting. Proceedings of the National Academy of Sciences, 122(42), e2512779122–e2512779122. https://doi.org/10.1073/pnas.2512779122