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'Tear-free' onion could be on the menu

By Marsha Walton
CNN Sci-Tech

Laura Jim, who works for an onion grower, helps to pick one out of the ground.
Laura Jim, who works for an onion grower, picks one out of the ground.

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(CNN) -- It's as certain as death and taxes. Chopping onions makes people cry.

Now scientists in Japan say they may have discovered a way to dry the tears without taking away any of the taste.

Researchers at one of Japan's largest food companies, House Foods, have identified a previously unknown onion enzyme that helps form the chemical that makes people cry. Shinsuke Imai and his team say the enzyme is not tied to an onion's flavor. So they believe a genetically modified onion, created without this enzyme, would taste just as good as the original.

But such an onion is still years away, the researchers say. Experts say a good next step is trying to show the gene exists in other members of the onion family, such as leeks.

"There are some big gaps in the study," said University of Georgia horticulture professor Bill Randle. "We need more evidence that this is definitely what happens."

Imai and his team worked on unraveling this mystery for eight years before finding the enzyme in yellow onions. They called the enzyme lachrymatory-factor synthase, a name derived from the Latin word for tears. Their research, published this week in the British Journal Nature, says the enzyme is responsible for producing propanthial S-oxide, which is the onion's tear-inducing factor.

"We can't precisely predict how the flavor of 'tear-free' onions will change when the activity of lachrymatory-factor synthase is suppressed," said Imai. "However, its suppression would not introduce any new flavor compounds that are foreign to traditional onions, so we are anticipating no dramatic change in the flavor of the 'tear- free' onion."

Keeping an eye on the research

Georgia onion grower R.T. Stanley, Jr. says he'll watch the research closely. A tearless onion could be a goldmine for growers.

"I'm very interested in anything that could improve our Vidalia onions, and this would be a big improvement," he said.

Stanley says the sweet Vidalias, which have had a huge surge in popularity since the 1970's, are not as irritating to the eyes as some other varieties. But he says an onion's tear-causing strength is tied to environmental factors, such as cultivation methods and harvesting time.

"Certain varieties seem to be sweeter and don't burn your eyes as much when you cut them," said Stanley, who grows 1,000 acres of onions each year.

Long road filled with tears

Cultures the world over have enjoyed this pungent, versatile crop for more than 5000 years, and put up with the stinging eyes that come with slicing and chopping them.

Chefs and cooks have dozens of theories about how to minimize the sting of an onion's tears. A few popular hints, with NO promise of effectiveness: wearing goggles, keeping a candle lit near the cutting board, wearing a bag over your head, peeling and chopping with a piece of raw potato, or bread, or a lemon wedge, or a sugar cube in your mouth; or heating the onion before chopping.

Chuck Tietz, chef and kitchen manager in Atlanta's Outback Steakhouse, offers a few tips.

"You can put onions in the freezer for about five to ten minutes," he said. "You can also leave the water running next to your chopping board to keep the air circulating. Or you can build up a tolerance like me. I can now chop around 200 onions before it affects me."

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