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?
-
I think the vitamins part of the question is probably okay, since it's not really nutritional, just a food storage and preservation question.– Cascabel ♦Commented May 14, 2014 at 14:39
-
1I'm glad this was migrated. I'm interested in answers.– Jolenealaska ♦Commented May 14, 2014 at 15:18
-
7What'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 StrangerCommented May 14, 2014 at 15:35
-
1Not 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.– EcnerwalCommented Jun 2, 2015 at 23:53
-
These are cool: qphotonics.com/Deep-UV-light-emitting-diodes I didn't realize they'd gotten all the way down to 240nm. Not sure it's right top call these things LEDs, since we can't see the output. X-Ray "LEDs" are next.– Wayfaring StrangerCommented Jun 19, 2017 at 23:33
|
Show 1 more comment
5 Answers
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.
-
2There 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). Commented Jun 3, 2015 at 13:07
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.
-
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!)– Cascabel ♦Commented May 14, 2014 at 19:36
-
1Thank 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 ? Commented May 21, 2014 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.
answered May 14, 2014 at 16:48
-
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...– Cascabel ♦Commented May 14, 2014 at 19:36
-
True, Bacteria and molds are everywhere. But a fridge would be an airtight, closed environment. It should be possible to achieve a higher level of sterility here. Or indeed reduce the number of pathogens. Certainly over a considerable amount of time (over multiple nights). If not, sterilization would not be possible at all.– theking2Commented Aug 8, 2020 at 15:10
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?
-
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... Commented Jun 3, 2015 at 12:58
Is it a sub zero? Sub zero uses a uv light to filter the air every 20 minutes not light up the entire fridge. It is taking bacteria and odors as well as ethelyne gas out of the air circulated in the fridge. This is not a new concept Revco corporation introduced this at least as far back as the 60's in their bilt-in Gourmet line. They continued it until they stopped making home refrigeration in the late 70's or early 80's. They continue to make lab refrigeration so they probably continue to use uv air filtration.
