For decades, chefs have dropped tears while slicing onions, but a new study finally explains why and how to stop it. Researchers at Cornell University have discovered that the tear -inducing fog from onions does not appear in a burst that previously thought. Instead, it happens in two quick steps: a high -speed spray followed by slower drip formation. Their high -speed imaging revealed that blunt or rapid knives dramatically increase the number and energy for these drops and drive sharp sulfur compounds in the air. The simple fix? Keep the knives sharp and cut gently to reduce the fog and keep your eyes dry.
Science behind onions tears
When an onion is cut, enzymes with sulfur compounds react to creating vision-propanial-S-oxide, the gas that makes you cry. But this new study, published in the Proceedings of the National Academy of Sciences (PNAS), adds a mechanical twist. Researchers found that it is not just chemistry, it is physics as well. The cutting movement causes a “drip outbreak”, where fluid is thrown out violently from the onion’s damaged cells. Faster cuts and dull leaves generate higher impact, break more cells and output more annoyingly loaded aerosols in the air.With the help of ultra -speed cameras, the researchers analyzed how leaves interact with the onion’s layer. A sharp knife slices clean through the tough outer skin and the inner mesophyll, which causes minimal compression. In contrast, a dull or heavy leaf on the onion is cut before it is cut, releases more liquid and creates powerful Mini explosions “of fog. These microbars have tear -inducing drops longer and faster, directly to the face.
Practical kitchen advice to stop tears
The results confirm what many chefs have long been suspected: a sharp knife is not only safer and more efficient but also tear -free. The researchers suggest that they maintain regular knife -sharing routines and use smooth, steady movements instead of aggressive chopping. In addition, cutting of onions near a soft air flow, for example under a kitchen valve, can help spread aerosols before reaching your eyes.
Beyond Tears: Hygiene Implications
Interestingly, the study suggests broader kitchen benefits. The drip outbreak mechanism can play a role in spreading bacteria and food -borne pathogens during cooking. By reducing the amount and speed of ejected drops, sharper leaves can help limit microbial spread and improve total kitchen hygiene.
