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I have a new fridge in which there is, apparently, some LEDs emitting UVs. I read on the internet that it kills bacteria and helps the food last longer. Does this really work? And what about the claim that it somehow preserves vitamins?

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migrated from May 14 '14 at 12:59

This question came from our site for contractors and serious DIYers.

I think the vitamins part of the question is probably okay, since it's not really nutritional, just a food storage and preservation question. –  Jefromi May 14 '14 at 14:39
I'm glad this was migrated. I'm interested in answers. –  Jolenealaska May 14 '14 at 15:18
What's the wavelength of these LED's? What's the output in mW per square centimeter at the food surface? Are the fridge shelves UV transparent or are there shadowed areas? It's POSSIBLE to sterilize things with current generation UV-LED's, but it's also a great marketing gimmick. –  Wayfaring Stranger May 14 '14 at 15:35
Not having run across this gimmick, I don't know how they are arranged in the fridge. I know that germicidal lamps are used to kill airborne germs in fixtures arranged (overhead or in ventilation ducts) so that they don't expose eyes to the light - so I could imagine they might be doing something similar to reduce germs/spores without needing to directly irradiate all food surfaces. But gimmick still seems like the most accurate explanation. –  Ecnerwal Jun 2 at 23:53

4 Answers 4

It's for sterilizations -- for years they've sold "UV pens" for hikers to sterilize water, and kits with UV lamps to keep fish tanks clean.

Of course, it won't help if items are in opaque containers, tightly packed, wrapped in foil, etc ... so you'll likely need to start using clear containers for it to be beneficial ... and even then, it'll only help the outside of the food, and the shelves and walls of the fridge, not the inner portions of the food being stored.

UV light also causes clear plastics to degrade over time. They'll become less transparent (typically taking on a yellow/brown hue), and become more brittle. ... so it could also cause you to need to replace your storage containers much more often.

I have no knowledge of UV affects on vitamins.

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I can't imagine it has any real effect on vitamins/nutrients, since it's just affecting the surface. (Unless you're comparing to food that spoils and gets thrown out and therefore does not supply you any vitamins!) –  Jefromi May 14 '14 at 19:36
Thank you for your answer ! I don't do anything special to keep my aliments in some transparent containers, they are just translucent. Now that I have been using my fridge for a while I saw that my aliments are degrading less less quicker than on my old fridge so I am having hard time telling wether it comes from the temperature that is cooler or if it's because of the UVs or... both of them ? –  Trevör Anne Denise May 21 '14 at 16:56

Whether UV might help a food last longer depends on what the food is.

Fats (like shortening or ghee), and most spices should be protected from light. The UV in sunlight is part of what turns fats rancid, and helps dried herbs and spices loose their flavor.

You will never achieve a truly sterile environment at home. Bacteria and molds are everywhere, in the air, on every surface. In any case, any reduction in pathogens due to the UV is strictly a surface treatment, and the food will be quickly recolonized from the environment.

I recommend practicing good sanitation (such as not cutting vegetables on a board just used for raw chicken) in general, and not worrying about a gimmick such as a UV light.

I cannot speak to the stability of vitamins under UV.

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So I'm guessing the best case is for really sensitive foods that go off quickly from the surface, so if you're lucky and everything's powerful enough, keeping the surface a little cleaner could make the spoilage take a couple times as long... –  Jefromi May 14 '14 at 19:36

UV light will destroy bacteria etc. On direct contact only

They are used in commercial food storage to self clean all the surfaces of the food storage system and containers placed within it

Food should be in light proof containers if the UV light is very strong, or there will be some surface degradation

For a domestic fridge, this is most likely a marketing gimmick, though it may help reduce odors etc. if the owner doesn't clean the fridge very well or often?

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Since the problematic germs tend to be on the surface of the produce, why should it not work - another question is how to irradiate all sides of a given piece of produce without moving it... –  rackandboneman Jun 3 at 12:58

Yes, the UV light will make your fruit and vegetables last longer. Really it depends on the wavelength of UV. 275nm is used for killing bacteria and will burn your retinas, 385nm is less harsh to the skin or eyes and will still kill bacteria to a degree.

I just read a study in which they used 285nm in a controlled refrigerator setting against a static test with no UV on strawberries and how long they would stay fresh. The UV irradiated strawberries lasted 9 days without growing mold. The non uv, started growing mold all over them by 9 days. They tested the nutritional content of each and the UV treated had a higher content of nutrition then the non uv.

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There are 285nm LEDs and even 254nm LEDs available ... and since you can switch them off the moment the fridge door is opened, you could use them ... Problem: Most glass containers are black to those wavelengths (even Pyrex - actually that is exactly how the UV-A/B/C bands were defined, by what kinds of glass did or did not filter the radiation). –  rackandboneman Jun 3 at 13:07

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