A truism as old as strawberry picking is the observation that the juicier and tastier the strawberries, the more quickly the berries turn to a mushy heap of rot and mold, even in the fridge. An answer to longer fruit storage may come with research showing that selective UV light inhibits both decay and the growth of mold. With new LEDs able to produce specific types of UV light, we might see gadgets for use in the fridge that keep produce fresher longer.
It's not that researchers are blind to the potential of UV light in food preservation. However, traditional mercury-based sources of UV have been shown to dry out produce. And while UV-C has long been known to be a germicide, in experiments done by the US Department of Agriculture (USDA), UV-C inhibited mold growth but only worsened any existing damage in the berries. However, UV-B was found to inhibit both mold and rot, potentially by inducing defense mechanisms in the berry itself.
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The issue then lies in selectively generating the desired wavelength of UV light. Manufacturing LEDs that can span the full spectrum of UV light has been a challenge, but Sensor Electronic Technology, Inc. (SETi) developed technology to produce LEDs capable of only emitting UV-B. The tests the USDA did with the new LEDs showed fruit stayed mold-free for nine days, twice as long as compared to fruit refrigerated in the dark.
UV-B light inhibits both mold and decay, with circled areas highlighting a damaged portion of the berry
The lead researcher from the USDA said of the potential of this technology, "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.”
I'm intrigued by the promise of such a device tomorrow, but if you'll excuse me, I have some strawberries to salvage today.
Source: The Optical SocietyView gallery - 4 images