June 5, 2013
Study: UV Light Doubles Shelf Life Of Strawberries
redOrbit Staff & Wire Reports — Your Universe Online
Just in time for the summer berry season, scientists at the US Department of Agriculture (USDA) have demonstrated a way to delay spoilage of fresh strawberries for up to several days.The researchers showed that low irradiance ultra-violet (UV) light directed at strawberries over long exposure periods at low temperature and very high humidity -- typical home refrigerator conditions -- doubles the shelf life to nine days.
The team used a novel device incorporating light-emitting diodes (LEDs) that emit UV at wavelengths found in sunlight transmitted through Earth's atmosphere. The findings are important because previous attempts using traditional UV light sources for storage of produce resulted in severe drying, and it was unknown if the advantages of long exposure to low-level UV light would be effective against rot.
LEDs are now commonplace thanks to their long life, energy efficiency and ability to span the wavelength range from near UV to infrared. However, the full UV spectrum has presented challenges for LED manufacturers — until recently.
Sensor Electronic Technology, Inc. (SETi) in Columbia, S.C, which collaborated with the USDA on the work, developed a special technology to fabricate UV LEDs across the entire UV spectrum from UVA to UVC. This flexibility allowed them to tune the emitted light to the wavelengths most effective for this application.
"UV-LEDs presented the opportunity to try low power devices that work well in the cold and can be engineered to work in small spaces such as refrigerator compartments," said lead USDA researcher Steven Britz, who will present the findings next Thursday at the Conference on Lasers and Electro-Optics (CLEO: 2013).
Using strawberries purchased from a local supermarket, Britz's team placed one batch in a dark refrigerator and one batch in a refrigerator exposed to UV-LEDs. The results showed the UV-treated berries had their shelf life extended twofold -- nine days mold-free -- over darkened berries, as judged by weight, moisture content, concentration of select phytochemicals, visible damage, and mold growth.
Based on these promising results, the researchers are working to commercialize the technology for use in home refrigerators.
"These findings are expected to have a major impact on the appliance business to extend the shelf life and preserve nutritional value of fresh produce while reducing waste and saving money for every household," said Remis Gaska, president and CEO of SETi.