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bioBot
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Sterilizing that which is not Substrate
#26200505 - 09/21/19 02:19 AM (4 years, 6 months ago) |
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Sterilizing an object at 256F which is not substrate, such as a tool or empty jars, is the same length of time required to achieve sterilization as it would be for substrate?
If an object like a wooden cup were cooked in an oven at 256F for 35 min, would it become sterilized?
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Shroomei
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Re: Sterilizing that which is not Substrate [Re: bioBot]
#26200629 - 09/21/19 05:53 AM (4 years, 6 months ago) |
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Direct answer: No, 256F 35 minutes dry heat is not recommended for sterilization.
If you use a pressure cooker: smaller objects (spoon, ect) are wrapped in aluminum foil and PC-ed at 15psi for 30 minutes. Vessels have to be open so that steam can enter. The opening is covered with aluminum foil or filter paper.
If you want to put objects in an oven that is dry heat sterilization. Wikipedia gives some recommended temperature settings starting at 320F for 2h. E.g. I wrap my glass petri dishes in aluminum foil put them in the cold oven set to 200C and switch it off after 2h. That might be overkill but the oven and packages need some time to warm up.
I'd assume wooden objects would crack or char if subjected to dry heat sterilization. Maybe they survive PC-ing, however as they are porous you would go for longer sterilization times that with glass or metall objects.
Edited by Shroomei (09/21/19 11:57 AM)
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Tormato
The Goddess Kali Meh 😛
Registered: 07/01/17
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Re: Sterilizing that which is not Substrate [Re: Shroomei]
#26200832 - 09/21/19 08:56 AM (4 years, 6 months ago) |
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Quote:
Shroomei said: 115psi for 30 minutes.
Pretty sure you meant 15psi right?
-------------------- Helpful Threads The Shroomery Store Tormato's Q&A Thread Post Questions Here or PM me! "Lately it occurs to me what a long, strange trip it's been." ~ Grateful Dead Before you start...Do you have a Pressure Cooker and a Dehydrator? I highly recommend getting both!
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Shroomei
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Re: Sterilizing that which is not Substrate [Re: Tormato]
#26201071 - 09/21/19 11:59 AM (4 years, 6 months ago) |
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Quote:
Tormato said:
Quote:
Shroomei said: 115psi for 30 minutes.
Pretty sure you meant 15psi right?
Err, yes. F...g touch pad key board.
115 psi would make it more like 30 seconds
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bioBot
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Re: Sterilizing that which is not Substrate [Re: Shroomei]
#26201753 - 09/21/19 06:54 PM (4 years, 6 months ago) |
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Doesn't sound good for dry heat sterilization. Thanks for the info.
It may be better to somehow add moisture into the dry heat oven, attain 256F, and possibly cook for less time than two hours.
Moist heat sterilization - W.pedia
The disintegration of aluminum foil with heat may be a good reason to avoid it altogether and use polypropylene plastic instead. Small particles of aluminum will break off from foil after exposure to heat, and possibly go on to contaminate the human body.
Risk Assessment of Using Aluminum Foil in Food Preparation
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SHROOMSISAY01
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Re: Sterilizing that which is not Substrate [Re: bioBot]
#26202120 - 09/22/19 12:52 AM (4 years, 6 months ago) |
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Quote:
bioBot said: Doesn't sound good for dry heat sterilization. Thanks for the info.
It may be better to somehow add moisture into the dry heat oven, attain 256F, and possibly cook for less time than two hours.
Moist heat sterilization - W.pedia
The disintegration of aluminum foil with heat may be a good reason to avoid it altogether and use polypropylene plastic instead. Small particles of aluminum will break off from foil after exposure to heat, and possibly go on to contaminate the human body.
Risk Assessment of Using Aluminum Foil in Food Preparation
It doesn't work like that. To get steam to 250F (250F is 15psi) you need pressure. That is why we use pressure cookers.
As far as aluminum goes I believe RR sent off mushrooms that had eaten through an aluminum turkey pan. No traces of aluminum were found in the mushrooms.
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Shroomei
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Re: Sterilizing that which is not Substrate [Re: bioBot]
#26202542 - 09/22/19 10:08 AM (4 years, 6 months ago) |
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Quote:
bioBot said:
The disintegration of aluminum foil with heat may be a good reason to avoid it altogether and use polypropylene plastic instead. Small particles of aluminum will break off from foil after exposure to heat, and possibly go on to contaminate the human body.
Risk Assessment of Using Aluminum Foil in Food Preparation
Aluminum foil is useful if you want your tool stay sterile when you take it out of the PC.
You can use any suitable wrapping you like inside a pressure cooker (the home equivalent of an autoclave) just make sure there is a way steam can enter and it can stand the temperature. Industry or for medical use there are e.g. paper&plastic bags or steel boxes.
If you want to work with an oven: The oven bags can stand up to 200C (392F) afaik. Or a pyrex dish with lid could do the same job.
As I do not lick my petri dishes I should be fine.
Aluminum foil is susceptible to exreme pH and salt containing solutions especially when combined with heat.
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DnDRnD
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Re: Sterilizing that which is not Substrate [Re: Shroomei]
#26202599 - 09/22/19 10:36 AM (4 years, 6 months ago) |
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Quote:
Shroomei said:
Quote:
bioBot said:
The disintegration of aluminum foil with heat may be a good reason to avoid it altogether and use polypropylene plastic instead. Small particles of aluminum will break off from foil after exposure to heat, and possibly go on to contaminate the human body.
Risk Assessment of Using Aluminum Foil in Food Preparation
You can use any suitable wrapping you like inside a pressure cooker (the home equivalent of an autoclave) just make sure there is a way steam can enter and it can stand the temperature. Industry or for medical use there are e.g. paper&plastic bags or steel boxes.
What do you mean make sure steam can enter? We don't want steam to actually enter our jars/bags because that would mess up the water content
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Shroomei
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Re: Sterilizing that which is not Substrate [Re: DnDRnD]
#26202696 - 09/22/19 11:38 AM (4 years, 6 months ago) |
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Quote:
DnDRnD said:
What do you mean make sure steam can enter? We don't want steam to actually enter our jars/bags because that would mess up the water content
Excuse me that was sloppy speach. A steam autoclave will evacuate the chamber and then flood it with saturated steam - several cycles to get rid of residual air. Therefore you need gas exchange or your wrapping or vessel might burst. Further remaining air pockets will not reach the full temperature.
To my understanding jars and bags have a filter or polyfill covered opening allowing gas exchange. Upon heating the pressure cooker steam is generated in the jars pushing out most of the air. Upon cooling some steam and air is sucked back in. The intake of steam did not seem to be a problem so far.
Wrapped dry tools in a PC will have to rely on diffusion to get steam in and air out of the wrapping. only remotely related: I once tried to PC sealed bags with substrate - three out of five burst. The remaining started smelling. Bad idea.
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DnDRnD
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Re: Sterilizing that which is not Substrate [Re: Shroomei]
#26202776 - 09/22/19 12:15 PM (4 years, 6 months ago) |
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Ahhh no I get your saying now
I was thinking you meant like you wanted a opening into the jar so that steam could pour into it if that makes sense
Haha my bad that was my confusion
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