Saturday, October 15, 2005

Why Do Onions Make Us Cry?

Many people enjoy the taste of onions in their meals. Indeed, the average American eats about 18.3 pounds of onions each year. Onions are healthy components of the human diet because they contain vitamins B and C, protein, calcium, iron, and quercetin (an antioxidant, which helps to neutralize harmful substances in our bodies that cause tissue damage and aging). In addition to being full of nutrients, onions are low in fat and sodium.

However, if you have ever cut into an onion, it is likely that your eyes filled with tears. Why does this happen? How can we enjoy the taste and benefits of onions without the tears? Read on to find out.

When you cut into an onion, an enzyme (i.e. a molecule that speeds up chemical reactions) called lachrymatory-factor synthase is released into the air from the ruptured onion cells. This enzyme converts some of the proteins in the onion into sulfenic acids, eye irritants which are responsible for the flushing action of our tears. Sulfenic acids are also responsible for the strong odor of raw onions.

So, how can we enjoy the benefits and the great taste of onions without the tears? Here are several methods that can reduce the amount of sulfenic acids that reaches the eyes:

  • After peeling, put the onion in the refrigerator or freezer for a few minutes to slow the speed of the chemical reaction.
  • Run the onion under cold water while slicing, or cut it underwater.
  • Cook the onion before slicing.
  • Do not rub your eyes, because they will be coated in irritating compounds from the juice of the onion.
  • Cut the onion in a plastic bag with the bottom cut out.
  • Turn the vent fan on high and place your cutting board next to the stove top.
  • Try pouring a small amount of white distilled vinegar on your cutting board before slicing.

Over time, it is even possible to develop a tolerance for the chemical, reducing the amount of reaction.

Go on, put your new eye defense skills to the test with the help of a parent or other handy adult with the Little Lion experiment of the month!

Little Lion Experiment:

This onion soup recipe from the National Onion Association is full of flavor, and makes a tasty treat. To make it, you will need:

  • 4 large yellow onions
  • 6 tablespoons butter or margarine
  • 1 tablespoon sugar
  • 2 quarts reduced sodium chicken broth
  • Salt and pepper to taste
  • baguette French bread, sliced and toasted
  • Grated Romano cheese
  • An adult to help you

To begin, slice the onions, using any of the above methods to reduce eye irritation. Be careful with the knife, and always point the sharp part of the blade away from you when cutting. Melt the butter or margarine in a large saucepan that holds at least 4 quarts. Next, add the onions and cook over medium heat, stirring often, for 12 minutes or until tender and golden. Add sugar and stir for one minute. Next add broth, cover, and bring to a boil. Reduce heat, and simmer for 12 minutes. Season the soup with salt and pepper to taste.

Finally, ladle soup into bowls and top with toast and cheese. Enjoy!