Re: [CH] need help w/ pressure cooker (aka poor man's autoclave)

=Mark (mstevens@exit109.com)
Tue, 9 Jun 2009 16:05:52 -0400 

We used a pressure cooker to sterilize agar culture tubes and containers of
oats for growing mushrooms in college (a biology ptoject OK?).  We used about
1.5 inches of water for a 20 QT cooker, I expect you would use less.  We
cooked ours for one hour but we were using quart mason jars for the growth
medium which had a larger mass than what you're working with.  Otherwise the
procedure sounds good...

On Tue, 9 Jun 2009 14:41:28 -0500, Jim Graham wrote
> I've just bought a medium-sized (8 qt) pressure cooker for sterilizing.
> Its pressure regulator works at 15 PSI, which I every source I have read
> or talked to has said is correct for that magic temperature, 250 deg F
> (121 deg C).
> 
> I have two primary uses in mind.  The first use is sterilizing 
> culture media for brewing yeast, mostly for making 10 mL starters--
> -I bought autoclavable tubes and caps from Cynmar Scientific for 
> these.  Along with that, I'll also be using it for making and 
> sterilizing new agar plates when the ones I bought are all used up.  
> I have 600 mL beakers
> (also from Cynmar) for putting the starter tubes (and plates, when I 
> get to that point) into.  The beakers are also autoclavable.
> 
> The second use that I have in mind is for sterilizing bottles of hot
> sauce the next time I make some (that way I don't have to rely on the
> pH being low enough).
> 
> Ok, here's what I THINK I need to do....
> 
> If I understand correctly, I open (just slightly) the containers that
> I'm sterilizing...both to vent, and to expose the contents to the steam.
> Then I put those into the beakers, PUT SOME UNKNOWN AMOUNT OF WATER
> (need help here for sure) in the bottom of the pressure cooker (oh,
> and the rack is assumed to be in there, too).
> 
> Then, (again, as I understand it), I seal it up, put the rocker on 
> top, and turn the stove way up and let it rock.  When the rocker starts
> going like a bat outta hell, start a 20 minute timer, and after 20,
> remove it from the burner.  After the pressure is released, I open it
> up (no air movement allowed in the kitchen while I'm doing this---I
> know that much from culturing yeast in general) and tighten all of 
> the caps and put the tubes into the test tube rack.
> 
> Does that all sound about right?  What amount of water should I use?
> Am I missing anything?
> 
> Thanks,
>    --jim
> 
> -- 
> 73 DE N5IAL (/4)        | Peter da Silva:  No, try "rm -rf /"
> spooky130u@gmail.com    | Dave Aronson:    As your life flashes 
> before < Running FreeBSD 7.0 > |      your eyes, in the unit of time 
> known as an ICBM / Hurricane:       |      ohnosecond....    
>  (alt.sysadmin.recovery)
>    30.39735N 86.60439W  |


--
=Mark

http://www.exit109.com/~mstevens