Why Chopping Onions Makes Us Cry?

Onions are a common ingredient in many dishes, adding flavor and aroma to the food. However, chopping onions can also cause a lot of tears and irritation in the eyes. Why does this happen? How can we prevent it? In this post, we will explain the science behind the onion-induced crying and some tips to avoid it.

The Science of Onion-Induced Crying

The reason why eyes water while chopping onions is that onions release a chemical that irritates the eyes. This chemical is a result of a biochemical defense mechanism that onions have developed to protect themselves from microbes and insects. When we chop an onion, we break its cells and release an enzyme called alliinase. This enzyme reacts with a sulfur-containing amino acid in the onion, producing a sulfenic acid.

Another enzyme then converts the sulfenic acid into a lachrymatory factor (LF), which is a gas that can easily spread in the air. When this gas reaches our eyes, it reacts with the water in them, forming a sulfuric acid. This acid burns and stings our eyes, triggering the nerve endings to send a signal to the brain. The brain then responds by producing tears to wash away the irritant.

The LF gas is also responsible for the pungent smell of onions, which can affect our nose and mouth as well. The LF gas can bind to the receptors in our nose and mouth, causing a burning sensation and a bitter taste. This can also make us sneeze or cough, as our body tries to expel the irritant.

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The Tips to Avoid Onion-Induced Crying

There are some methods that can help us reduce or prevent the tears and irritation caused by chopping onions. These methods are based on the principle of reducing the amount or the effect of the LF gas that reaches our eyes, nose, and mouth. Some of these methods are:

Refrigerate or freeze the onions before chopping: Refrigerating or freezing the onions can slow down the chemical reactions that produce the LF gas. Therefore, chopping cold onions will release less gas and affect our eyes less. It is enough to refrigerate the onions for at least 15 minutes or freeze them for a few minutes before chopping.

Chop the onions in water: Chopping the onions in water can prevent the LF gas from escaping into the air. Therefore, the gas will not reach our eyes and bother us. We can chop the onions in a pot of water or in a bowl of water, depending on the amount and size of the onions.

Use a sharp knife to chop the onions: Using a sharp knife can cut the onion cells with less damage, releasing less enzyme and gas. Therefore, our eyes will be less irritated by the gas. We should check the sharpness of our knife before chopping and sharpen it if necessary.

Wear glasses or goggles while chopping onions: Wearing glasses or goggles can protect our eyes from the LF gas. Therefore, the gas will not contact our eyes and cause us discomfort. Wearing glasses or goggles is one of the simplest and most effective methods to avoid onion-induced crying. It does not matter if the glasses or goggles are with or without lenses. The important thing is that they cover our eyes.

Conclusion

Eyes water while chopping onions because onions release a chemical that irritates the eyes. This chemical is a result of a biochemical defense mechanism that onions have developed to protect themselves from microbes and insects. Chopping onions can also affect our nose and mouth, causing a burning sensation and a bitter taste. There are some methods that can help us reduce or prevent the tears and irritation caused by chopping onions, such as refrigerating or freezing the onions, chopping the onions in water, using a sharp knife, and wearing glasses or goggles. These methods can help us chop onions without crying and enjoy their flavor and aroma.