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?
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.
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.
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.
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?
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.