Watery eyes while chopping onion comes from the sulfur compounds released from the cut cells mixing into the air and, on contact with the eye, forming a mildly irritating gas. When an onion is cut, its cell walls break down, and enzymes mix with sulfur-containing compounds to produce a volatile compound that stings the eyes.
When this compound comes into contact with the moist surface of the eye it creates a mild irritation, and the brain senses this and stimulates the tear glands. An onion being fresh and large increases the concentration of sulfur compounds, which can make the tearing more pronounced. The sharpness of the chopping knife also matters; a dull knife crushes the cells more, increasing gas release.
What Should Be Done to Reduce Watery Eyes While Chopping Onion?
With a few simple precautions, watery eyes while chopping onion can be reduced significantly. While these precautions have small effects individually, the difference is noticeable when applied together.
- The onion should be chilled in the refrigerator 15-20 minutes before chopping.
- The knife should be kept sharp; chopping with a dull knife should be avoided.
- Chopping should be done near an open window if possible, or somewhere with good ventilation.
- The root end of the onion should be cut last; the root is the area where sulfur compounds are most concentrated.
- Breathing through the mouth while chopping can reduce the vapor reaching the nose.
What Mistakes Are Made When Chopping Onion?
Some habits when chopping onion can make watery eyes even worse. Being aware of these mistakes makes time spent in the kitchen more comfortable.
- Chopping the onion at room temperature, without chilling it first, increases gas release.
- Cutting the root end first causes more sulfur compounds to be released.
- Using a dull knife crushes the cells and releases more gas.
- Chopping in a closed, poorly ventilated space causes the vapor to concentrate.
Does the Onion Variety Affect the Intensity of Tearing?
The concentration of sulfur compounds varies among onion varieties; pungent dry onions generally cause more tearing than red onions. Growing conditions in the soil and the onion's ripeness are also factors that affect sulfur content. Those wanting a less tear-inducing result can choose red onion when the recipe allows for it. It's also observed that freshly harvested onions can create a more intense smell and tearing effect than onions that have been stored for a long time.
Does Soaking Onion in Water Reduce Tearing?
Soaking the onion in cold water for about half an hour before chopping can help some of the volatile compounds on the surface leach into the water, reducing tearing. Wearing goggles while chopping is also a practical method that physically blocks the gas from directly contacting the eyes. Some traditional methods, like placing a candle nearby, don't have a consistent effect, so chilling, a sharp knife, and good ventilation stand out as the most reliable methods.
Watery eyes while chopping onion are a natural result of the sulfur compounds released and cannot be completely prevented. However, chilling the onion, using a sharp knife, and chopping in a well-ventilated place noticeably reduce the tearing. When these simple precautions are combined, chopping onions in day-to-day kitchen work becomes much more comfortable and manageable.