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Iceberg lettuce goes healthier

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Friday May 22, 2009 (foodconsumer.org) -- Called the “polyester of lettuce,” iceberg lettuce has fallen out of flavor, so to speak, in recent years. In the ’60s and ’70s, Americans started realizing the truth behind the pale, white ball of lettuce: it is about 95 percent water and doesn’t have the flavor and nutrition of the upscale salad greens.

A team of plant physiologists are rejuvenating the listless image of this lettuce. Using ultraviolet light-emitting diodes (LEDs), the team has developed a way to make iceberg lettuce darker and redder, and therefore healthier.

Steven Britz of the U.S. Department of Agriculture in Beltsville, Maryland, and colleagues used low-powered LEDs that shine ultraviolet light on the iceberg lettuce to help create red leafed lettuce. It’s the red tinges on the lettuce that give color to berries and apple skins. When bombarded with ultraviolet rays, the red lettuce leaf creates polyphenolic compounds in its outer layer of cells.

The polyphenolic compounds are powerful antioxidants. Diets rich in antioxidants are known to provide a variety of health benefits, from improving brain function to slowing the aging process.

After exposure to 43 hours of the UV light, the growing lettuce plants were noticeably redder than other plants that only saw white light. The redness on the plants seemed to increase as the intensity of the light increased, noted the researchers.

“We’ve been pleasantly surprised to see how effective the LEDs are,” said Britz, “and are now testing how much exposure is required and whether the light should be pulsed or continuous.”

Because most produce is not grown in greenhouses, crops grown in winter months receive very little UV light to begin with. By exposing these greenhouse crops to the ultraviolet LEDs, Britz and his team hope to enhance the richness of the winter crops as well.

Britz and his colleagues will present their research at the 2009 Conference on Lasers and Electro Optics/International Quantum Electronics Conference from May 31 to June 5 at the Baltimore Convention Center.

(By Sheilah Downey, and edited by Heather Kelley)

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