News

26 May 2009

 

UV LEDs yield deeper-color antioxidant-rich plants

Plant physiologists led by Steve Britz of the US Department of Agriculture in Beltsville, MD have developed a method using ultraviolet LEDs to create darker, redder lettuce with more nutritional value than iceberg lettuce, for example, since darker colors in leafy vegetables such as spinach are often signs of antioxidants, which are thought to have a variety of health benefits.

The researchers say that the dark red tinges on a leaf of red leaf lettuce are created when the sun's ultraviolet rays strike the plant, which creates UV-absorbing polyphenolic compounds in the outer layer of cells. Some of these compounds are red, and help to block the UV radiation, which can mutate plant DNA and damage the photosynthesis process.

To create red leaf lettuce plants enriched with antioxidant compounds, Britz exposed them to about 10mW/m² of UVB light (a component of natural sunlight) from low-power LEDs. After 43 hours of exposure, the lettuce plants were noticeably redder than other plants that only saw white light.

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

The research will be presented at next week's 2009 Conference on Lasers and Electro Optics/International Quantum Electronics Conference (CLEO/IQEC) in Baltimore, MD (on 31 May to 5 June).

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Visit: www.usda.gov