This method was effective, but destroyed the onions. Chi Thai, a UGA food scientist and member of the research project team, is now searching for nondestructive ways, like infrared scanning, to measure these factors.

And, as part of the study, Norman Schmidt of Kansas' Tabor College, uses a gas chromatograph. "(Dr. Schmidt) is measuring the factor that makes you tear up. We want to relate that to our sensory data from the human trained panelist," Shewfelt said.

The scientists selected four Vidalia onion varieties for the study; one with high sweetness and pungency, one with high sweetness and low pungency, one with low sweetness and high pungency and one with low sweetness and pungency.

A trained consumer sensory panel tasted raw onion wedges and selected the two varieties with high sweetness as "superior acceptable." The panelists ranked the two varieties with low sweetness "unacceptable."

"The sweetness was the most important factor," Shewfelt said.

The UGA research team also held a taste test with untrained consumers at the Tate Student Center on the UGA campus in Athens.

"It was very hard to get people to try a sample of a raw onion," said Maureen McFerson, the graduate student working on the project. "I would ask them if they'd like to do something to help Georgia agriculture today? - not, 'Would you like to try a piece of raw onion?'"

A native of Washington state, McFerson is accustomed to eating Walla Walla sweet onions. As part of her master's thesis work at UGA, she met with growers in Lyons, Ga., to get their insight on Georgia's state vegetable.

"Most of the growers were concerned about the soil and growing conditions, finding out what consumers want and keeping a quality product," she said. "They also want an easy, nondestructive method to predict acceptability by consumers."

The research team discovered a "positive relationship between instrumental analysis and a trained panel and between different compounds and acceptability," she said.

"We found the absence of pungency compounds correlated to a higher amount of consumer acceptability," McFerson said. "And we made headway toward finding a nondestructive method through the infrared method and mathematical models."

The research team has more work to do before either method can be applied in the industry.

"In the long term, we want to find an instrumental method that can discriminate against various onions. If one is too pungent, it will be kicked out and not sold raw. It can be used another way," he said. "We know there are ways to identify pungency and sweetness, so you will be assured that the ones you get are of lower pungency."

McFerson now prefers Vidalia onions to Walla Wallas.

"Unlike peanuts, cotton and peaches, consumers know that they are supporting Georgia agriculture when they purchase a Vidalia onion," she said. "Like with Champagne in France, the onions must be grown in certain counties in south central Georgia to be the labeled Vidalia."

For more on Vidalia onion research at UGA, see the website at