low irradiance ultra-violet (UV) light directed at
strawberries over long exposure periods at low temperature and very high
humidity -- typical home refrigerator conditions -- delays spoilage. The team
used a novel device incorporating light-emitting diodes (LEDs) that emit UV at
wavelengths found in sunlight transmitted through Earth's atmosphere.
LEDs are now commonplace thanks to their long life and
energy efficiency, as well as 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.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 -- nine days mold-free -- over darkened
berries, as judged by weight, moisture content, concentration of select
phytochemicals, visible damage, and mold growth.
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