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pressure cooker question


carnivoor

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I'm thinking about giving TC a try and I've been wondering about the pressure cooker stage. Is the equipment sterilized by the steam or by the heat? The reason I ask is because I thought about wrapping some equipment like tweezers or paper towels in aluminium foil and put it in with my jars during the pressure cooking stage and this way I could then disinfect the outside from the foil and when it's in my workspace I could open the foil and have sterilized wipes etc...

Or maybe I could put some things in a bigger jar and spray that down before I bring it in to work with.

Also, I found sites that told me to spray the inside of my workspace with alcohol and others that say to use bleach, considering that some sites say to use a flame to keep the point of your equipment sterile ,I'm not sure alcohol is such a good idea.

Questions,questions...

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I'm thinking about giving TC a try and I've been wondering about the pressure cooker stage. Is the equipment sterilized by the steam or by the heat? The reason I ask is because I thought about wrapping some equipment like tweezers or paper towels in aluminium foil and put it in with my jars during the pressure cooking stage and this way I could then disinfect the outside from the foil and when it's in my workspace I could open the foil and have sterilized wipes etc...

Or maybe I could put some things in a bigger jar and spray that down before I bring it in to work with.

Also, I found sites that told me to spray the inside of my workspace with alcohol and others that say to use bleach, considering that some sites say to use a flame to keep the point of your equipment sterile ,I'm not sure alcohol is such a good idea.

Questions,questions...

Steam is just water. Water is non toxic to microbes so its the heat that kills. Steam does a better job because it is hotter than boiling water in an enclosed container and is a gas that can move around. The pressure also helps to destroy cells.

Wrapping equipment in foil is standard procedure in microbiol labs when sterelizing with steam (autoclave). It kills things inside as well as outside the foil. And when brought out the foil prevents microbes from settling on the equipment enclosed by the foil. So it will remain sterile until the foil is opened. They use foil as its cheap, easy to fold around the equipment and doesnt melt.

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Water does not kill contaminants, the heat does. Water steam just creates pressure, high pressure elevates boiling point of water, therefore higher temperature can be reached. At normal pressure water boils at 100C which is not hot enough to kill fungus, bacteria, viruses,etc over reasonable period of time .

Personally I use pressure cooker only for sterilisation of media. Other work equipment I sterilise inside the chamber spraying with 96%EtOH. Bleach and alcohol both have dis/advantages.

Alcohol is good because it is quite effective and non-toxic (you dont have to use gloves) but it cannot be used when there is an open flame nearby, otherwise instead of growing plants you get fried vegetables :shock:

Also, alcohol is very stable and if it gets inside the jars in too high concentration, it can harm the tissue.

Bleach, on the other hand, is not stable and decomposes over short period of time, so if you get some inside the jars, it will decompose and dont affect plants (of course, there is a concetration limit). Also, you can use it when you use flame as well for sterilisation. But big disadvantage is, that it is corrosive and very aggresive to materials and your hands, respiratory system, etc. So it should be used with great caution.

I use steam for jars&media, bleach for sterilizing tissues, alcohol for tools.

Of course, it is a matter of choice of each TCer:-)

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