May 19, 2009--Steven Britz, a plant physiologist from the U.S. Department of Agriculture (Beltsville, MD) and colleagues have developed a way to make lettuce darker and redder--and therefore healthier with more antioxidants--using ultraviolet light-emitting diodes (LEDs; see also "UV light could reduce spread of tuberculosis"). The research will be presented at the 2009 Conference on Lasers and Electro Optics/International Quantum Electronics Conference (CLEO/IQEC), which takes place May 31 to June 5 at the Baltimore Convention Center (see "CLEO/IQEC 2009: a hub of knowledge, activity").
When bombarded with ultraviolet rays from the sun, the lettuce leaf creates UV-absorbing polyphenolic compounds in its outer layer of cells. Some of these compounds are red and belong to the same family that gives color to berries and apple skin. They help block ultraviolet radiation, which can mutate plant DNA and damage the photosynthesis that allows a plant to make its food. Polyphenolic compounds,which include flavonoids like quercetin and cyanidin, are also powerful antioxidants. Diets rich in antioxidants are thought to provide a variety of health benefits to human beings, from improving brain function to slowing the wear and tear of aging.
To create red leaf lettuce plants enriched with these compounds, Britz purchased low-power LEDs that shine with UVB light, a component of natural sunlight. In small quantities, this ultraviolet light allows humans to produce vitamin D, which has been cited for its health benefits. Britz exposed the plants to levels of UVB light comparable to those that a beach goer would feel on a sunny day, approximately 10 milliwatts per square meter. After 43 hours of exposure to UVB light, the growing lettuce plants were noticeably redder than other plants that only saw white light.
The presentation titled "Shedding light on nutrition," is numbered PTuA3 and will be given by Steven Britz at 10:30 a.m., Tuesday, June 2.
For more information, go to www.cleoconference.org.