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Sterilization at 10 PSI?

PostPosted: Tue Jan 12, 2010 5:43 pm
by GuitarLord5000
I finally purchased a pressure cooker so that I could sterilize a bunch of cans of starter wort as well as bottles for frozen yeast cultures. Unfortunately, this pressure cooker only goes to 10 psi. I know that typically, 15 psi is what you want for sterilization. I've searched around the web, and I can't seem to find very much info about this. I know that sterilization is a function of time as well as temperature. Is there any chance of getting sterile wort out of this cooker? Maybe if I run 'em through the cooker for 90 minutes or so?

Cheers,
Dave

PostPosted: Tue Jan 12, 2010 6:06 pm
by yeastmeister
Hmmmm...Lets start out with the basics...at 15 psi, a pressure cooker can get to 121C (249.8F), at 10 psi it can only get to 116C (240.8F). Unfortunately, there are many organisms that can survive at 240F (Botulism is one of concern). There is no substitution for time, as botulism can survive at 240F indefinitely. So, while your pressure cooker can cook foods faster, I wouldn't use it for long term storage. Sorry.

If possible, return the unit and get one that goes to 15psi, otherwise, maybe you can call the manufacturer and see if they sell a 15psi weight for that unit.

Whatever you do, DON'T attempt to modify it yourself. A pressure cooker is a bomb waiting to go off. Thats how I describe it to my kids every time I use mine ... "Stay away from the bomb".

PostPosted: Wed Jan 13, 2010 7:53 am
by aleguy
Yeah. What you really need is a pressure CANNER, which is designed for exactly that. Sterilizing food substances for long-term storage. A pressure COOKER is only designed to save time and fuel for cooking. Just not interchangeable. Return it if you are able, and get a pressure canner instead. One caveat, though. measure the inside dimensions of the canner before you buy it. There are several out there that claim to hold so many quarts, etc. but the inner dimensions don't allow for quart jars to fit along with the necessary rack.
a good, but expensive, source for quality canners is www.fungiperfecti.com

PostPosted: Wed Jan 13, 2010 1:02 pm
by GuitarLord5000
Thanks for the responses. I was afraid that 10 PSI wouldn't cut it for my needs. The good news is, I returned the 6 qt cooker ($35) and picked up an 8 qt pressure cooker on sale at sears for only $25. Looks like it'll be able to hold 4 quart size mason jars at a time, versus only 2 for the 6 qt cooker, and this one goes to 15 psi.

I realize that a canner would be ideal, but this pressure cooker should work, right? I wanted the cooker because I like to cook, and I've actually been wanting one for a long for just that purpose. Sterilizing equipment is just a practical offshoot.

Thanks again,
Dave

PostPosted: Wed Jan 13, 2010 2:14 pm
by redtail28
I have a pressure canner like the yeastmeister.
It's from Wal-mart now it cost about a 100 bucks
but it holds 7 qt jars I think. Now these canners are
seasonal items. It goes up to 15 psi.
I also cook in mine beef stew in 25 minutes with
the meat falling apart . I brown the meat then
pressure cook it for 15 minutes at 10 psi then
let it rest to bleed off the pressure. Add vegetables
and cook for 10 more minutes.
I have also tryed a roast but you need the rack
to keep it off the bottom.

PostPosted: Wed Jan 13, 2010 2:56 pm
by yeastmeister
Yep, they are seasonal in the stores, but if you go online to walmart and type in "pressure canner", look for the 23 quart one. Its $79.97 with free site to store shipping so you can pick it up at your nearest walmart. Its available all year long online.

PostPosted: Thu Jan 14, 2010 4:25 pm
by GuitarLord5000
Well, I went ahead and canned some sterile wort today with my pressure cooker. I was a bit shocked at how dark the starter wort turned out to be. I realize that the maillard reaction will be greater at 250 degrees versus the normal 212, but the canned wort (made with Muntons Light DME) ended up being as dark as Guiness! Is this normal?

PostPosted: Fri Jan 15, 2010 7:12 am
by yeastmeister
Yep, thats normal. It will lighten up when you put yeast in it, but don't worry about the color. Its such a small amount your pitching into a batch that the color won't change. If you've seen my Belgian Wit, you know its very light in color. It is always made with dark starter from sterilization.

PostPosted: Fri Jan 15, 2010 11:23 am
by Imakewort
yes it is normal, but for me I chill and decant all the liquid but enough to cover the yeast, shake it to thoroughly mix the yeast and pitch. I make a lot of (or used to) lagers and do not want to pitch a 5 liter starter.

PostPosted: Fri Jan 15, 2010 2:37 pm
by GuitarLord5000
yeastmeister wrote:Yep, thats normal. It will lighten up when you put yeast in it, but don't worry about the color. Its such a small amount your pitching into a batch that the color won't change. If you've seen my Belgian Wit, you know its very light in color. It is always made with dark starter from sterilization.


Imakewort wrote:yes it is normal, but for me I chill and decant all the liquid but enough to cover the yeast, shake it to thoroughly mix the yeast and pitch. I make a lot of (or used to) lagers and do not want to pitch a 5 liter starter.


Thanks for the responses. I wasn't too worried about changing the color of my beer. I also tend to chill and decant most of the starter before using. I was actually more worried that I might have scorched the DME somehow, and that the sugars wouldn't be fermentable. I'm glad to hear that dark wort is the norm when using a pressure cooker.

Cheers,
Dave