6th June 2013

UV light in food storage could double shelf life

Researchers in the U.S. have doubled the shelf life of strawberries, using a new device that could soon be commercialised for home refrigerators.

A team from the U.S. Department of Agriculture (USDA) and Sensor Electronic Technology, Inc. (SETi) demonstrated that low irradiance ultra-violet (UV) light exposure of strawberries in low temperature and very high humidity – typical home refrigerator conditions – can delay spoilage over long periods. The researchers developed a novel device incorporating light-emitting diodes (LEDs) that emit UV at wavelengths found in sunlight transmitted through Earth's atmosphere.

The results, to be presented next week at the Conference on Lasers and Electro-Optics (CLEO: 2013), are significant 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 and energy efficiency, and their ability to span the wavelength range from near UV to infrared. The full UV spectrum, however, had presented challenges for LED manufacturers – until recently. SETi 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," says lead USDA researcher Steven Britz.

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. Results showed the UV-treated berries had their shelf life extended twofold – up to nine days mould-free – over darkened berries, as judged by weight, moisture content, concentration of select phytochemicals, visible damage and mould growth. Based on these encouraging results, the team is now working to commercialise the technology for 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," states Remis Gaska, president and CEO of SETi.

Spoiled and wasted food is a huge problem in the world today. Earlier this year, a report estimated that 2 billion tons is thrown away each year, up to half of all food produced globally. This new technology could go some way towards reversing this trend, which is vital to ensure that 9 billion people are adequately fed by 2050.

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