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/sci/ - Science & Math

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16023390 No.16023390 [Reply] [Original]

Do mason jars absorb UV-C light?After some reading it seems pickling jars/mason jars are made out of tempered glass which is heat resistant but it should allow short wavelengths through.
Let's say i have a water/liquid solution in a jar and i want to sterilize/disinfect it with a UV-C light.The jar and the light source would be in a box which sides are covered with aluminium foil. Would it even work? If so how close would the jar need to be and what kind of light source would be effective at this task?
Also what about using it on different substrates that are in the jar and not liquid?
For example i put pasteurized popcorn in a jar and then expose it to UV-C light,occasionally shaking the jar in the meantime.Would this do anything regarding the remaining bacteria/spores embedded in the pores of the corn? Will these substrates degrade in a meaningful way from a one time exposure?

Also i'm planning to use it for petri dishes made out of polypropylene. Will these degrade (significantly that would negatively impact their usage or even make them unusable) just from a few occasions of exposure to UV-C? Seen some videos of UV-C light used on agar and it seemed to work. Though in case of petri dishes before agar pour i could use hidrogen peroxyde. After the pour though UV-C usage would be ideal to really make sure nothing grows on them before inoculation.

It would be really nice to avoid the usage of a pressure cooker if possible and use only UV-C light for these purposes.

>> No.16023412

I know from my research on off grid water purification the UV light in the water purification system is housed in a tight fitting tube. This is so the water's profile facing the UV light is as thin and small as possible. I read that bacteria and viruses and such can shade each other out or easily get missed by the full on impact of the UV bulb. A think jar of water would likely provide ample room for microscopic things to hide and settle outside the reach of your light. You'd need a combination of agitation of the liquid and a set amount of time to guarantee 100% of possible contamination has been exposed to the UV light.

I'd assume this shading problem only compounds when you add solid matter like popcorn. The popcorn would provide endless areas for contamination to hide from UV light. I'm not well read on food preservation at industrial levels but I think this is why they pasteurize with steam or even radiation when possible. Both would penetrate all areas and not suffer from the shading issue UV light has. If your UV light is strong enough to penetrate a popcorn kernel I'd wager it might also cook it.

Your petri dishes might work as they are technically a 2D surface and the UV light can be put close enough to penetrate all places but if I'm not mistaken you only need to sterilize the surface of the agar as you should have poured it hot enough that the interior of the agar is sterile. You'll have to run experiments to be sure the UV will work, when in doubt pressure cook.


>> No.16023759

So i would need the tube in the water body for it to work which is what i hoped to avoid but i guess that makes sense.
Guess i'll need a pressure cooker after all,won't i?

>> No.16023781
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>> No.16023902

UVC is used in sewage plants to sterilize clarified effluent water, so I think the absorbance of UV-C by water is low enough that it can travel a decent distance through it to keep it's sterilizing effects.

Dunno if a few mm of glass will be enough to prevent the UVC sterilizing the inside of the glass jar. I imagine it will probably penetrate fine.

If your planning on reusing petri-dishes, glass might be better. No idea how long modern disposable ones will hold up for. Probably be fine for quite some time as petri-dishes don't need to hold much weight.
But they might chemically degrade which could have unknown effects on whatever's growing in them.

tldr, i've no source but I think UVC will probably be fine for sterilization provided the light can reach every surface in need of sterilizing.

>> No.16024637

Yes, almost all glasses short of quartz absorb UV-C substantially. I've tested the transmission using UV-C and UV-C reactive fluorescent screens in the past. It gets filtered substantially.

>> No.16024745

Hmm,thanks for the replies. I think i'll get a pressure cooker for the jars and maybe get a smaller UV-C light for additional safety for the petri dishes.