How do you keep sterile equipment sterile or close to it?

[jasonclick]

question about keeping lab glassware sterile. If I put my flasks and beakers in the pressure cooker to sterilize them, is there a way to keep them sterile if I don't use them right away?

 

[trentm]

Sure. They will remain sterile until opened or contaminated in some way. Covered with foil or some other manner will work for several months. Store them in a clean cabinet away from drafts.

 

[grainbill]

I use "saranwrap" for mine, after sanitizing. I do not know if that is good or bad but I have not had any problems with contamination. Now that I'm thinking about it, foil might be the way to go. I can always give the foil a spritz of starsan prior to wrapping....

 

[trentm]

The best practice is to cover with something (foil is standard) before sterilization (pressure cooking). That way there is no chance of contamination after you open the cooker.

 

[jasonclick]

The best practice is to cover with something (foil is standard) before sterilization (pressure cooking). That way there is no chance of contamination after you open the cooker.

do you put some type of liquid in the container... like a little water in the flask for instance to assure it get's hot enough on the inside to sterilize?

 

[trentm]

No, it's not necessary. Your pressure cooker will heat everything inside it to 250F as it reaches 15 psi, after 20 minutes everything inside is sterile. I'm curious though why you are sterilizing empty flasks?

 

[SnakeRidge]

If you're dry sterilizing glassware, you don't even need to use a pressure cooker. Just cover your glassware with foil and place in the oven at 250* for 30'. As long as the foil remains intact, the inside of the flask is sterile. Be careful not to crimp the foil when wrapping, though, as this can create tiny holes in the foil that COULD allow contaminants in.

 

[jasonclick]

No, it's not necessary. Your pressure cooker will heat everything inside it to 250F as it reaches 15 psi, after 20 minutes everything inside is sterile. I'm curious though why you are sterilizing empty flasks?

it takes so long for my pressure cooker to get up to temp and then cool down I figured if I'm sterilizing one piece of equipment for something I'm working on, if I have room to go ahead and sterilize other pieces so they are ready to go when needed.

 

[jasonclick]

If you're dry sterilizing glassware, you don't even need to use a pressure cooker. Just cover your glassware with foil and place in the oven at 250* for 30'. As long as the foil remains intact, the inside of the flask is sterile. Be careful not to crimp the foil when wrapping, though, as this can create tiny holes in the foil that COULD allow contaminants in.

thanks. I didn't ever think about using the oven.

 

[trentm]

If you're dry sterilizing glassware, you don't even need to use a pressure cooker. Just cover your glassware with foil and place in the oven at 250* for 30'. As long as the foil remains intact, the inside of the flask is sterile. Be careful not to crimp the foil when wrapping, though, as this can create tiny holes in the foil that COULD allow contaminants in.

For true dry heat sterilization higher temps at are longer times are required. Here is a link for the requirements: http://www.cdc.gov/hicpac/Disinfection_Sterilization/13_10otherSterilizationMethods.html

However, full sterilization is not required for most homebrew applications, even starters. If you are storing yeast on slants or freezing and/or growing up from slants etc, sterilization is important.

 

[SnakeRidge]

For true dry heat sterilization higher temps at are longer times are required. Here is a link for the requirements: http://www.cdc.gov/hicpac/Disinfection_Sterilization/13_10otherSterilizationMethods.html

However, full sterilization is not required for most homebrew applications, even starters. If you are storing yeast on slants or freezing and/or growing up from slants etc, sterilization is important.

Learn something new every day. I work in a microbiology lab, and we've always used 250*F for 30' to dry sterilize (of course, we're growing bacteria on purpose....)

Thanks for the info.