When it comes to onions, most of us want it both ways-we want to have our onion and eat it, too. We want the health benefits that onions provide without the pungency, which can cause halitosis, heartburn and hyperactive tear ducts. University of Wisconsin-Madison researcher Michael Havey and his colleagues in Argentina and Turkey are interested in developing a sweet, less pungent onion that does a body good.

Onions have several health benefits, said Havey, professor of horticulture at the College of Agricultural and Life Sciences and research scientist for the USDA Agricultural Research Service. It is well documented that the vegetable contains a natural blood thinner in the form of thiosulfinates, sulfur-based compounds that inhibit aggregation of platelets, which can cause heart attacks and strokes. Thiosulfinates are also responsible for the pungency and, consequently, teary-eye effects of onions.

Another class of compounds found in onions are fructans, complex carbohydrates that are good sources of soluble dietary fibers. They have been associated with lower rates of colorectal cancers. In addition, fructans give onions their sweetness.

Therein lies the problem. Sweet onions with low pungency, like the Vidalias from Georgia, have a higher water content, said Havey, and fewer of the beneficial fructans. “The more pungent the onion, the higher the carbohydrate concentration,” said Havey. “If it accumulates fructans, it retains less water and concentrates both the carbohydrates and thiosulfinates.”

In the research paper, “QTL affecting soluble carbohydrate concentrations in stored onion bulbs and their association with flavor and health-enhancing attributes,” published in the June 2004 issue of the journal Genome, Havey and co-authors Claudio Galmarini of the National University of Cuyo in Argentina, Ali Fuat Gokce of Uludag University in Turkey, and Cynthia Henson of the Agricultural Research Service and agronomy department at UW-Madison, discuss their field research on onions.

“We are trying to develop an onion that retains some water, has a high level of fructans, stores well and is not pungent,” said Havey. But finding a breed of onion that is widely accepted by consumers is the tricky part. When it comes to onions, not all breeds are created equal, he said.

“Preference for various types of onions, such as color, texture and pungency, is culturally determined,” Havey said. Hispanics, he said, tend to prefer white onions, while the yellow is the classic American onion. Red onions are the mainstays in the Caribbean, India and Indonesia.

Onions are the world”s second most economically important vegetable crop, said Havey. They are second only to the tomato in farmgate value. Onions are grown in more than 175 countries, led by China, then India, the United States, Turkey and Pakistan. Onions are found in many processed foods, from salsa and soup to salad dressing and spaghetti sauce. In the United States, onions corner approximately $4 billion of the retail market. According to the National Onion Association, per capita consumption ranges from 18.7 pounds per year in the United States to a whopping 66.8 pounds per year in Libya.

Onions must be versatile. They can impart flavor to a slow-cooked pot roast, add zest to a stir-fry dish, create crunch in a salad or enhance the taste of a sandwich. “There are onions that will blow your socks off,” Havey said. One particularly pungent onion – New York Bold – is marketed as “Onion with an attitude.” It is too pungent for the average consumer to eat fresh, said Havey, but makes a good cooking onion. However, the moment you cook an onion, the thiosulfinates are driven off and you lose some of the health benefits.

Havey”s research showed that bulb onions that were stored for 90 days accumulated sucrose from the breakdown of the more complex fructans, thus retaining the thiosulfinates and becoming sweeter in the process.

“The sweetening of onion during storage could have huge economic value,” Havey said. “Onions have the potential to enhance the health of consumers. The future looks bright and rosy for the onion.”