Onions without tears

By JOE O'CONNELL, cbbqa past President 

Dicing and mincing

Chefs learn a few tricks to eliminate tears when dicing or mincing onion.

First, peel onions under cold running water.  Second, refrigerate the entire onion before beginning to peel or slice it.

Of course, the chief cook (the word "chef" is a French word which means "chief cook") usually assigns the onion preparation task to the assistants.  If none is available, then the food processor can be used to dice or mince without tears.

The science

If you recall basic high school chemistry, you'll remember that some chemicals are neutral (a Ph of 7.0), some chemicals are acidic (a low Ph, under 7.0), and others are basic (a high Ph, over 7.0).  Barbecue cooks often use onions and chile peppers in rubs and mops, so they should know that the onions are acidic and chilies are (usually) basic.  Used together, they tend to neutralize each other.  (Whether this is good or bad depends on what the cook is trying to accomplish.)

Onions are acidic.  They contain a chemical called propanethial S-oxide, which is the tear-producing villain.  The chemical is released when an onion is sliced and becomes airborne, where it combines with the moisture in the eyes to produce sulfuric acid!  No wonder you cry.

Peeling onions under cold water washes away the S-oxide before it becomes airborne, while refrigerating onions slows down the S-oxide release into the air.

Bill Wight's note:
Other methods that work to reduce/eliminate tearing while chopping onions include, chopping in front of a fan blowing across your chopping area, wearing a SCUBA diving mask and chopping onions in a salsa maker.

Credit:  Julia Child, The Way to Cook (New York:  1989), page 358.